REDUCTION OF MALODOUR IN SOILED ANIMAL LITTER

Abstract: The present invention relates to an animal litter composition comprising an oxidoreductase for reducing the malodour emanating from soiled animal litters and to the process of preparing and using such compositions.

Description: Title: Reduction of malodour in soiled animal litter FIELD OF THE INVENTION The present invention relates to an animal litter material comprising an enzyme capable of preventing, inhibiting and/or reducing development of malodour emanating from the litter material when soiled with urine or other wastes from humans or animals. The invention also relates to a process for producing such litter material and a method for reducing formation of malodours in soiled litter materials. BACKGROUND OF THE INVENTION The control of odour in animal litter has been a continuing problem as such litter materials most frequently are used indoors. Also most often the litter is not changed immediately after an animal, e.g. a cat, has relieved itself in the litter material, and such soiled litter may remain indoors in the open box for prolonged periods of time at ambient temperature, thus facilitating development of foul odours. Especially feline urine may develop a foul odour. Suggested solutions include the use of bacteriostats such as: halogenated aromatic hydrocarbons (U.S. Pat. No. 4,494,482, Arnold, issued Jan. 22, 1985); soluble salts of transition metals of Group lb or Group lib of the periodic table of elements, especially zinc, which are taught as both bacteriostats and urease inhibitors (U.S. Pat. No. 4,494,481, Rodriguez et al . , issued Jan. 22, 1985 and U.S. Pat. No. 4,736,706, Lang, issued Apr. 12, 1988); boron containing compounds which are claimed to be urease inhibitors (U.S. Pat. Nos. 4,949,672 and 5,176,108, Ratcliff et al . and Jenkins et al . , issued Aug. 21, 1990 and Jan. 5, 1993 respectively); sodium bisulfite complexes (U.S. Pat. No. 5,267,531, Appel et al . , issued Dec. 7, 1993); and sodium or potassium bicarbonate (U.S. Pat. Nos. 5,303,676 and 5,421,291, Lawson and Lawson et al . , issued Apr. 19, 1994 and Jun. 6, 1995 respectively) . Other approaches to controlling odour include the use of absorbents for odour such as cyclodextrin and polycarboxylate polymers (U.S. Pat. Nos. 4,727,824; 4,844,010; 4,881,490; and 4,883,021, Ducharme et al . , issued Mar. 1, 1988; Jul . 4, 1989; Nov. 21, 1989; and Nov. 28, 1989 respectively) . Still another approach of "covering up" the bad odour involves using encapsulated perfumes (U.S. Pat. No. 4,407,231, Colbo et al . issued Oct. 4, 1983). Thus, many commercial animal litter products contain a fragrance to mask the malodour and to provide a freshness impression. Many of these fragrances are developed with human aesthetic preference in mind, apparently without consideration of the effect to the animal. Thus, many perfumes used in commercial animal litter compositions contain significant amounts of ingredients that are repulsive to animals e.g. cats. On the other hand, commercially available products which claim control of animal behavior, such as cat repellent and cat attractant products, contain only the purported active ingredients without consideration to human aesthetics. Many types of materials are used as animal litter. Clay and various cellulosic materials are commonly used, as disclosed in the above patents and additional disclosures of materials that can be used are fond in U.S. Pat. Nos.: 5,064,407, Peiffer, issued Nov. 12, 1991; 5,100,600, Keller et al . , issued Mar. 31, 1992; 5,207,389, Hall et al . , issued May 4, 1993; 5,209,186, Dewing, issued May 11, 1993; and 5,229,348, Ivie, issued Jul. 20, 1993. Preferred animal litter materials are those that "clump" to permit ready removal of the material that has been contacted by, e.g., urine and/or feces, such as U.S. Pats. Re. 33,983, Hughes, issued Jul. 7, 1992 and 5,193,489, Hardin, issued Mar. 16, 1993. All of the above patents are incorporated herein by reference. It is well established that malodour may be caused by a number of compounds including Volatile Surphuric compounds (VSC) , nitrogen containing compounds and short fatty acids. A source of nitrogen containing compounds, such as ammonia, is urine, faeces and blood giving a bad smell known by most people from soiled animal litters. The bad smell coming from soiled animal litter is at least partly a consequence of growth of bacteria, especially Escherichia coli , Enterococcus spp . and Proteus spp . present on the skin in the perineum (the region between the anus and the external sexual organs) . All strains of Proteus spp . form the enzyme urease during their metabolism. Urease has the ability to rapidly break down urea (constituting about 2% of human urine) into ammonia causing an unpleasant odour. Also in WO 98/27261 an animal litter is described incorporating odor absorbing materials such as cyclodextrins or zeolites and antimicrobial agents or urease inhibitors such as metallic salts or various organic compounds. The litter may also contain a protease enzyme for digestion of excretions. DESCRIPTION OF DRAWINGS Figure 1, in which Z = bactericidal activity in log cfu/ml; X = mg/1 Curvularia verruculosa haloperoxidase; Y = mM H 2 0 2 , shows a response surface plot for the antibacterial activity in artificial urine of a haloperoxidase (rHP) against a mixed culture of E. faecalis, E. coli and P. mirabilis adhering to CTMP. SUMMARY OF THE INVENTION A solid liquid absorbing animal litter material is provided, comprising an effective amount of an oxidoreductase (EC 1.-.-.- ) enzyme that inhibits the formation of odour from soils present in the litter material. The oxidoreductase preferably has at least one attribute selected from the group consisting of antimicrobial activity, urease inhibition activity, oxidation of malodorous compounds activity and/or mixtures thereof, but preferably the oxidoreductase will possess all properties . The invention also encompass in a additional aspects a process for reduction of malodour in soiled animal litters comprising contacting the soiled animal litter with an effective amount of oxidoreductase, the use of oxidoreductases for reduction of malodour in animal litters and a process for preparing an improved animal litter comprising the step .of adding an oxidoreductase to the animal litter composition. DETAILED DESCRIPTION OF THE INVENTION The animal litter composition of the invention comprises, besides from oxidoreductases conventional litter material such as described infra . CONVENTIONAL ANIMAL LITTER MATERIALS: CONVENTIONAL BASIC SOLID LIQUID ABSORBING MATERIAL: Any solid liquid (moisture) absorbing material suitable for use, e.g., as an animal litter is suitable for use in the present invention. Suitable examples include minerals, typically clay such as kaolinites, montmorillonites, or bentonites; fly ash as obtained from the burning of coal; but also absorbing fibrous materials or webs, like paper, cellulosic webs, or polymeric fibrous webs; wood chips; alfalfa; bark; straw; sand; pelletized absorbing litter materials (e.g. sawdust or polyurethane foam); and the like, including mixtures thereof. Other examples of suitable solid absorbing litter materials are disclosed in U.S. Pat. No. 3,921,581, issued Nov. 25, 1975 to Brewer, incorporated herein by reference. In one absorbent composition, there is a major amount of a cellulosic material, e.g., a cereal or grain hull, or peanut hulls, along or preferably in admixture with, a second cellulose material comprised of plant pulp, either vegetable or fruit pulp. The cellulosic material, hulls and pulp are ground to a desirable particle size and admixed with a minor amount of a suitable binder, up to about 20% by weight. Suitable binders are the carbohydrates, protein or mixtures thereof, such as flour and starch from plant sources, and the synthetic binders disclosed hereinafter. The cellulosic hull materials will generally be obtained from cereal grain sources such as corn, rice, wheat, oats and the like, soybean, sunflower and cotton seeds or peanut hulls. The plant pulp materials are generally obtained from vegetable sources such as beets, tomato, apple, grape or citrus pulp generally obtained for citrus fruits such as oranges, lemon, lime, grapefruit and the like. The carbohydrate binders are generally flours and starches from cereal grains such as corn, rice, wheat, oats and the like. Protein such as gluten found in wheat flour, or protein from bean or seed sources such as soybean or flaxseed and the like also provide suitable binders. Other materials that can be used for litters , include clay or clay-like materials. Their ability to absorb, or adsorb, moisture makes them excellent candidates for litters. Suitable litters include specific clays such as Georgia White clay, attapulgite, bentonite, kaolinite, halloysite, montmorillonite, smeetite, vermiculite, hectorite, diatomaceous earth, Fuller's earth, fossilized plant materials, expanded perlites, gypsum and other equivalent litter materials known to those skilled in the art. Preferred clays are those having water expanding crystal lattices, such as bentonite, i.e., montmorillonite. The clay particles can be comminuted. That is, they are pelletized or formed into particles which have a size varying from about 200 mesh USS (0.075 mm) to about 3 mesh (5.6 mm), preferably from about 60 mesh (0.25 mm) to about 4 mesh (4.75 mm) . A desirable property, which is characteristic of certain natural earths which may be used as litter, is the tendency to "clump" . Clumping is a tendency, marked in certain earths and less marked or absent in others, for the earth particles to adhere firmly to each other when wet to form a mass having sufficient physical integrity to enable it to be removed from the remainder of the particles without undue crumbling or loss of peripheral litter material. The liquid with which the litter has been wet is entrained in the clump and is removed with it. Where the earth has good clumping properties substantially all of the liquid can be retained in the clump and the portion of the earth which remains after the removal of the clump can be completely dry. This property provides a means for removing urine from used litter which, in conjunction with the physical removal of feces, results in a residue of relatively uncontaminated litter, with diminished levels of undesired odours. The litter can then be replenished with fresh litter. This represents an economical use of litter in comparison with the complete replenishment of the litter. The present invention is especially good when the litter has clumping properties, which further limits the amount of odor that is created. If the litter has only poor or medium clumping properties, or if better clumping is required, one can use techniques such as are found in U.S. Pat 5,193,489. The litter can be an earth, for example, such as a montmorillonite or other smectite, suitably in the alkaline earth metal form, an attapulgite, a palygorskite or a sepiolite. U.S. Pat. No. 5,014,650 relates to litter comprising a porous, inert solid substrate, such as a clay, containing a cellulosic ether in an amount sufficient to agglomerate the animal urine deposited on the litter to form a gelled agglomerate having sufficient mechanical integrity to be conveyed from the litter box as a discrete entity. Additional polymers disclosed to be useful in the litter include polyvinyl alcohol, xanthan gum, gum acacia and various water-soluble polysaccharides . U.S. Pat. No. 4,676,196 describes an absorbing non-clay litter material comprising a mix of particulate litter materials which are caused to agglomerate to form noncompacted particles of a required size by tumbling in the presence of a moistened binder comprising starches, gums such as guar gum or glues. The US 5,193,489 patent provides an animal litter comprising a particulate earth substrate in admixture with a water soluble or dispersible polysaccharide selected from the galactomannan gums, said polysaccharide being present in an amount sufficient to increase the inherent clumping ability of the earth. A galactomannan is a polysaccharide mainly or wholly consisting of mannose and galactose, and preferably comprising a chain of mannose units bearing galactose side-chains. It is alleged that the galactomannans can be selected to be effective at relatively low concentrations and to give a fast clumping response. Vegetable based gums are usually marketed in a number of grades ranging from the relatively impure base gum, through purified gums from which some extraneous vegetable matter has been removed to derivatised gums which have been treated chemically to alter their characteristics in some way. The US 5,193,489 patent teaches that the gums are preferably relatively purified and can be derivatised, e.g. by reaction with propylene oxide to form the hydroxy propyl ether, to augment their hydrophilic character so as to be particularly effective. The gum can also be treated to reduce its alkalinity in aqueous dispersion or solution e.g. by the inclusion therein of a relatively weak organic or inorganic acid for example one having a pK value in aqueous solution of at least 4.0. Preferred galactomannan gums are guar gum or derivative thereof. The concentrations of cellulose ethers specifically disclosed to be effective in U.S. Pat. No. 5,014,650 range from 0.3% upwards with some failures at 0.5% by weight. The galactomannans used according to the US 5,193,489 patent are alleged to give effective clumping at concentrations down to 0.05% by weight of the earth (dry weight) or below in certain instances and are preferably used in from 0.02% to 1% by weight although any larger quantities, for example up to 2.5% or more by weight may also by used. Such litters are mixed with particles of the polysaccharide. The earth preferably has a particle size mainly, for example at least 95% by weight, in the range of about 10 mesh (1.7 mm) to 140 mesh (0.11 mm), preferably about 18 mesh (1 mm) to about 100 mesh (0.15 mm) . The polysaccharide preferably has a similar size range. The presence of the polysaccharide in particulate form is alleged to encourage swift dissolution or dispersion in liquid, in comparison with gum which might have been deposited onto the earth particles from solution, and therefore to encourage a quick clumping response. Pelletized litter materials (e.g., sawdust or polyurethane foam) typically have particle sizes in the range from about 1 mm to about 1.3 cm, preferably from about 2.5 mm to about 1 cm. The basic litter material can be any of the art recognized materials, with those that have the ability to clump being preferred. CONVENTIONAL MATERIALS FOR INHIBITION OF ODOUR FORMATION: Besides from the oxidoreductase of the invention the litter may also optionally if desired contain conventional materials that inhibit the formation of undesirable odors such as described in WO 98/27261, typically conventional urease inhibitor and/or antimicrobial agents if desired. Although an oxidoreductase usually have both urease inhibiting and antimicrobial properties conventional urease inhibitors and/or antimicrobial agents may if desired be incorporated in the animal litter composition of the invention if additional effect is desired. Metal salts Such urease inhibitor and/or antimicrobial agent may be a metal salt, such as described in WO 98/27261 pp 6 and 7 in the section "Metallic salts" hereby incorporated in the present application by reference. Urease inhibitors Other conventional materials may serve as an urease inhibitor and/or suppresser such as described in WO 98/27261 pp 7-12 in the section "Urease inhibitors" hereby included by reference. Antimicrobials Conventional organic antimicrobials may also be used in the present invention. It is preferable to use a broad spectrum antimicrobial, e.g., one that is effective on both bacteria (both gram positive and gram negative) and fungi. A limited spectrum antimicrobial, e.g., one that is only effective on a single group of microorganisms, e.g., fungi, can be used in combination with a broad spectrum antimicrobial or other limited spectrum antimicrobials with complimentary and/or supplementary activity. A mixture of broad spectrum antimicrobials may also be used, Antimicrobials useful in the present invention can be bactericidal and/or bacteriostatic and/or fungicidal and/or fungistatic and/or a virucidal effect, wherein The term "bactericidal" is to be understood as the antimicrobial being capable of killing bacterial cells. The term "bacteriostatic" is to be understood as the antimicrobial being capable of inhibiting bacterial growth, i.e. inhibiting growing bacterial cells. The term "fungicidal" is to be understood as the antimicrobial being capable of killing fungal cells. The term "fungistatic" is to be understood as the antimicrobial being capable of inhibiting fungal growth, i.e. inhibiting growing fungal cells. The term "virucidal" is to be understood as the antimicrobial being capable of inactivating virus. Also in the context of the present invention the term λλ inhibiting growth of microbial cells" is intended to mean that the cells are in the non-growing state, i.e., that they are not able to progate. Suitable preferred antimicrobials and suitable amounts for its use in animal litter compositions are described in WO 98/27261 pp. 13 to 15 in the section "Antimicrobials" incorporated herein by reference. Here it is also noted that in general, it is desirable to limit, or exclude, materials that can have adverse effects. Therefore, it is desirable to exclude the more toxic metals and those elements such as boron, that can have adverse effects on the environment (e.g. boron can adversely affect citrus crops) . pH Control Materials and Proteases Other conventional materials known to inhibit the formation of odour include materials with pH activity. Especially useful materials are acidic materials that neutralize the amine molecules that are typically created by bacteria. Polymeric carboxylate materials like polyacrylic acid are useful for this purpose . Protease enzymes can be useful in preventing odour by digesting excretions in such a way that non-odorous products are created. They can also reduce odour by destroying other enzymes that break down excretions. The typical proteases are disclosed hereinafter in the section enzymes. ODOR ABSORBING MATERIALS: The animal litter compositions of the invention may contain an effective, i.e., odour-absorbing, amount of various odour- absorbing materials. For the purpose of the present invention, the liquid absorbing litter materials, such as clay, saw dust, and the like, as described supra , are not considered to be odour absorbing materials, except when specifically noted, because the novel development of this invention, I.e adding an oxidoreductase to the animal litter composition has the purpose of improving the malodour absorbing/neutralising capability of the litter compositions which already contain these liquid absorbing litter materials. Odour-absorbing materials control undesirable odour by various means to reduce the concentration, or availability, of the malodorous molecules in the ambient air, thus reducing or eliminating the undesirable smell in the air. Such materials include, for example, cyclodextrins, zeolites, activated carbon, kieselguhr, chelating agents, chitin, alkali metal carbonates and bicarbonates, pH buffered materials such as carboxylic acids, and the like. Preferred materials are those which absorb primary amines. Especially preferred are cyclodextrin and/or zeolite, disclosed herein to provide odour control benefits. Some partially neutralised hydrogel forming odour absorbing gelling materials, such as polyacrylate gelling material and acrylate grafted starch gelling material ( vide infra) , are also useful in the present invention to control certain ammonia-type odours. These materials also function as fluid absorbing materials. Zeolite Odour-Absorbing Agent In general terms, traditional zeolites comprise an aluminate/ silicate framework, with associated cations, M, providing overall electrical neutrality. Empirically, the zeolite framework can be represented as xA10 2 • ySi0 2 and the electrically neutral zeolite as x/n M • xA10 2 • ySi0 2 • zH 2 0 wherein: x and y are each integers, M is a cation and n is the charge on the cation. As noted by the empirical formula, zeolites may also comprise waters of hydration (zH 2 0) . M can be a wide variety of cations, e.g., Na + , K + , NH 4 + , alkylammonium, heavy metals, and the like. Zeolites which may suitably be included in the animal litter composition of the invention is described in WO 98/27261 pp 16 to 17 incorporated herein by reference. Cyclodextrins A preferred odour absorbing material which may be included in the animal litter composition of the invention is uncomplexed cyclodextrin. As used herein, the term "cyclodextrin" includes any of the known cyclodextrins such as unsubstituted cyclodextrins containing from six to twelve glucose units. Examples of suitable cyclodextrins may be found in WO 98/27261 pp 17 to 21 incorporated herein by reference. Activated Carbon Odour-Absorbing Agent The carbon material which may be employed herein is the material well known in commercial practice as an adsorbent for organic molecules and/or for air purification purposes. Carbon suitable for use herein is available from a variety of commercial sources under trade names such as CALGON Type "CP6", Type "PCB" , Type "SGL", Type "CAL", and Type "OL." Often, such carbon material is referred to simply as "activated" carbon or "activated" charcoal. Typically, it is available in the form of extremely fine, dusty particles (e.g., 0.1-300 microns) having large surface areas (about 200 to several thousand M2/g) . It is to be understood that any of the "air purifying" or "activated" carbons of commerce can be used in the practice of this invention. If the zeolites herein are optionally used in conjunction with the activated carbon, it is preferred (for aesthetics reasons) to coat the carbon with the zeolite using a binder. Other Odour-Absorbing Agents Other odour-absorbing agents which may be included as part of the composition of the invention includes kieselguhr, chelating agents, chitin, pH buffered materials, and the like. PERFUMES : Perfume is usually important in animal litter materials to disguise foul odours emanating from soil in the litter. The use of desirable, refreshing perfume ingredients to formulate a "refreshing perfume", can make the undesirable odours more palatable to the owners. Also, use of appropriate perfume ingredients can influence the animals' behaviour. For example, the right perfume ingredients in an "attractant perfume" can attract e.g. a cat to its litter box, its toys, scratching post, etc., and the right perfume in a "deterrent perfume" can influence the cat to stay away from objects such as furniture that it likes to use as a scratching post. The refreshing perfume compositions typically, and preferably, contain ingredients with odour characteristics which are preferred by humans in order to provide a fresh impression and deodorising benefit. Preferably, the perfume ingredients are selected predominantly from two groups of ingredients, namely, (a) volatile ingredients having a boiling point (BP) at normal pressure of less than about 260°C, and more preferably less than about 250°C, and (b) ingredients having significantly low detection threshold. Nonlimiting examples of preferred volatile perfume ingredients and preferred amounts in animal litter materials are described in WO 98/27261 pp. 22 to 27 in the sections "PERFUME" and "Perfume in animal litter" incorporated herein by reference . Cyclodextrin/Perfume Inclusion Complexes Perfume/cyclodextrin inclusion complexes known to the art which are a useful component in the litter material of the invention may be found in the prior art as well as suitable amounts for litter materials, perfume cyclodextrin ratios, suitable complex sizes and other relevant parameters, e.g. in WO 98/27261 pp. 27 to 29 in the section "Cyclodextrin/Perfume Inclusion Complexes" , incorporated herein by reference, which also refer to the disclosures Atwood, J.L., J.E.D. Davies & D.D. MacNichol, (Ed.) : Inclusion Compounds, Vol. Ill, Academic Press (1984) , especially Chapter 11, Atvood, J.L. and J.E.D. Davies (Ed.) : Proceedings of the Second International Symposium of Cyclodextrins Tokyo, Japan, (July, 1984), and J. Szejtli, Cyclodextrin Technology, Kluwer Academic Publishers (1988) , said publications incorporated herein by reference. Pressure-Activated or Moisture-Activated Perfume or Enzyme Microcapsules Microcapsules suitable for affixation to the animal litter of the invention such as disclosed in U.S. Pat. 4,407,231, Colbom et al, issued Oct. 4, 1983, or WO 97/24179 or WO 99/01500, all incorporated herein by reference, may be useful to the invention as a delivery system of fragrances or other active components such as the oxidoreductases of the invention or other enzymes. Such microcapsules, its use, amounts in litter materials, capsule sizes and other relevant capsule parameters are described in WO 98/27261 pp. 29 to 30 in the sections "Pressure-Activated Perfume Microcapsules" and "Moisture Activated Cellular Perfume Microcapsules" incorporated herein by reference. AOUEOUS CARRIER: Aqueous solutions are preferred in the present invention for the preparation of the animal litter and/or freshening the animal litter. The preferred aqueous carrier of the present invention is water. The water which is used can be distilled, deionized, or tap water. Water containing a small amount of low molecular weight monohydric alcohols, e.g., ethanol , methanol, and isopropanol, or polyols, such as ethylene glycol and propylene glycol, can also be useful. However, the volatile low molecular weight monohydric alcohols such as ethanol and/or isopropanol should be limited since these volatile organic compounds can contribute both to flammability problems and environmental pollution problem. If small amounts of low molecular weight monohydric alcohols are present in the composition of the present invention due to the addition of these alcohols to such things as perfumes and as stabilizers for some preservatives, it is preferred that the level of monohydric alcohol be less than about 10%, preferably less than about 5%, more preferably less than about 3%, by weight of the composition used to prepare the animal litter. SOLUBILIZING AID: The aqueous composition used to form the animal litter of the present invention can optionally, but preferably, contain a solubilizing aid to solubilize any excess hydrophobic organic materials, especially the perfume, and also optional ingredients which can be added to the composition, e.g., insect repelling agent, antioxidant, etc., that are not readily soluble in the composition. A suitable solubilizing aid is surfactant or wetting agent. In a spray product, it is preferred that the surfactant is a non-foaming or low- foaming surfactant. Suitable surfactants are nonionic surfactants, cationic surfactants, amphoteric surfactants, zwitterionic surfactants, and mixtures thereof, preferably nonionic surfactants and cationic surfactants, and mixtures thereof. Anionic surfactants are not preferred when the preferred urease inhibiting transition metal ions are present, because they can form water-insoluble salts with the metal ions. Suitable surfactants can be emulsifiers and/or detersive surfactants. Mixtures of emulsifiers and detersive surfactants are also preferred. The surfactant may suitably a conventional surfactant or mixtures thereof and in amounts and combinations such as described in WO 98/27261 pp. 32 to 34 in the section "SOLUBIZING AID" and incorporated herein by reference. BINDING AID: A suitable method of affixing solid powder active ingredients, such as uncomplexed cyclodextrin powder, perfumelcyclodextrin complex, perfume microcapsules, and enzymes is to form a slurry of said ingredients in a liquid carrier, preferably water, and then the slurry is sprayed onto the basic solid liquid absorbing material . The slurry can also be separately packaged in a suitable spray dispenser for spraying onto litter particles by an animal's owner. The enzymes such as oxidoreductases may also suitably be separately sprayed onto the animal litter material as an enzyme concentrate or as a slurry of amorphous or crystalline enzyme protein. Also the enzyme may be in a conventional granular form and mixed with the basic solid liquid absorbing material before spraying the slurry onto this mixture. The slurry can optionally include a suitable binding agent in an effective amount to help affix (improve the affixation) the solid powder active ingredients to the basic solid liquid absorbing material when the slurry is sprayed thereon. More particularly, suitable binding agents will function to form a bond between the solid powder or microcapsules and exterior surfaces of the basic solid liquid absorbing material which is strong enough to affix and hold at least a major portion of the solid powder active ingredients onto the substrate during handling, such as shaking, pouring and the like, as is encountered in packaging procedures. Suitable binding agents and amounts for use in this invention is described in WO 98/27261 p. 34 in the section "BINDING AID" and incorporated herein by reference. SUSPENSION AID: A suspension aid is optionally used to suspend solid powder active ingredients, such as uncomplexed cyclodextrin powder, perfume cyclodextrin complex, perfume microcapsules and enzymes, so that they are fairly evenly dispersed to form a relatively evenly distributed layer upon the basic solid liquid absorbing material's surface when the slurry is sprayed thereon. More particularly, for commercial preparation of the animal litter composition of this invention, the suspension agent should be present in a sufficient amount to provide suspension stability for the slurry (e.g., prevent separation, or settling, of the microcapsules and/or enzyme granules and particles in the slurry) , so that the slurry can be pumped and sprayed in metered amounts over a period of time. That is, the suspension agent preferably provides a stably suspended slurry for a length of time, e.g., at least about 12 hours, more preferably for greater than about 24 hours. The suspension agent should be dispersible in the slurry composition, and preferably thickens the slurry to a viscosity of at least about 100 centipoise. Preferred materials for use as the suspension agent are polyacrylic acids, such as are available from B. F. Goodrich as Carbopol (e.g., neutralized Carbopol 94 1) and from Rohm & Haas as Acrysol , which are very effective (in the neutralized form) in stably suspending microcapsules of the slurry at levels as low as about 0.01% to about 1%, more preferably from about 0.05% to about 0.2%, by weight of the slurry. Other preferred materials are particulate clays, such as smectite clay. A preferred clay suspending agent is calcium bentonite clay, available from Southern Clay Products under the trade name Bentolite~@ L. The clay suspension agent is preferably present at a level of from about 0. 1 % to about I 0%, more preferably from about 0. 3 % to about 5%, by weight of the slurry. The suspension agent must desirably be selected from materials which are compatible with the suspended actives and other ingredients. Thus materials which can substantially form complex with cyclodextrin should not be used to suspend uncomplexed cyclodextrin and/or cyclodextrin/perfume complex powder, and polyacrylates and ion-exchangeable clays should not be used in the presence of water soluble, heavy transition metal ions, such as zinc ions. Also the suspension agent should be dispersible in the liquid carrier, with water being the most preferred liquid carrier. CLEANING INGREDIENTS: Other cleaning components are the typical detergent surfactants at a level of from about 0.001% to about 1%, preferably from about 0.005% to about 0.5%, more preferably from about 0.05% to about 0.3% by weight of the composition. Detersive surfactants utilized can be of the anionic, nonionic, zwitterionic, ampholytic or cationic type or can comprise compatible mixtures of these types. Detergent surfactants useful herein are described in U.S. Patent 3,664,961, Norris, issued May 23, 1972, U.S. Patent 3,919,678, Laughlin et al . , issued December 30, 1975, U.S. Patent 4,222,905, Cockrell, issued September 16, 1980, and in U.S. Patent 4,239,659, Murphy, issued December 16, 1980. All of these patents are incorporated herein by reference . Detergent builders can optionally be included in the compositions herein to assist in controlling mineral hardness. Inorganic as well as organic builders can be used. Builders are typically used to assist in the removal of particulate soils. The level of builder, when present in the compositions, will typically comprise from about 0.1% to about 5%, more typically about 0.5% to about 1%, by weight, of detergent builder. Examples of suitable and preferred inorganic P-containing builders, nonphosphorous builders including silicates and carbonate builders, water-soluble, nonphosphorus organic builders such as, carboxylate or polycarboxylate builders, citrate builders, fatty acid builders and succinate builders are given in the art eg. in WO 98/27261 p. 38-40 in the section "CLEANING INGREDIENTS, INCLUDING ENZYMES" incorporated herein by reference, which also refers to the relevant documents on useful builder materials all incorporated by refererence: U.S. Patents 3,159,581; 3,213,030; 3,422,021; 3,400,148 and 3,422,137; U.S. Patent No. 4,605,509, U.S. Patent 4,664,839, issued May 12, 1987 to H. P. Rieck; DE-A-3 , 417 , 649 and DE-A- 3,742,043; German Patent Application No. 2,321,001 published on November 15, 1973; U.S. Patent 3,128,287, issued April 7, 1964; U.S. Patent 3,635,830, issued January 18, 1972; U.S. Patent 4,663,071, issued to Bush et al , on May 5, 1987; U.S. Patents 3,923,679; 3,835,163; 4,158,635; 4,120,874 and 4,102,903; U.S. Patent 4,566,984, Bush, issued January 28, 1986; European Patent Application 86200690.5/0,200,263, published November 5, 1986; U.S. Patent 3,308,067, Diehl, issued March 7, 1967; U.S. Patent 3,723,322; U.S. Patent 4,144,226, issued March 13, 1979 to Crutchfield et al ; U.S. Patent 4,246,495, issued March 27, 1979 to Crutchfield et al . OXIDOREDUCTASE ENZYMES The enzymes to be included in the animal litter composition oxidoreductases in accordance with the invention. However other enzyme types with completely different characteristics may be included such as proteases as known from the prior. The oxidoreductase in the context of the present invention may be any oxidoreductase or combination of different oxidoreductases or combination of oxidoreductases with other enzymes, which facilitates solution of the devised problems in animal litter compositions, primarily contamination and/or infection risks in soiled litter and development of foul odors in the soiled litter, by killing and/or inhibiting microorganisms, inhibitions of urease and/or oxidizing odorous components. One particularly advantageous feature of using oxidoreductases in animal litter compositions is that oxidoreductases will inhibit development of malodour and infection on all levels, i.e. (1) oxidoreductases will inhibit or kill microorganisms responsible for malodour development or infection, (2) even if some microorganisms survives and proliferate oxidoreductases will inhibit urease enzyme of such microorganisms from converting urea into malodorous compounds and (3) even if such malodorous compounds are developed oxidoreductases will oxidize such compounds into less odorous compounds. Another advantageous feature of using oxidoreductases in animal litter compositions is that oxidoreductases are biodegradable biological compound (proteins) . In that respect it is surprising that oxidoreductases will work in animal litter compositions, which have a completely different chemical composition than other composition in which oxidoreductases have been used. Yet another advantageous feature of using oxidoreductases in animal litter compositions is that oxidoreductases may be formulated into protective granules which may enable a slow release of the oxidoreductase so that the oxidoreductase is release from the granule when needed, e.g. upon wetting the animal litter composition. Methods of granulating enzyme are known to the art ( vide infra) such as fluid bed granulation, mixer granulation, prilling and/or extrusion providing enzyme granules having one or more protective or release controlling coatings. Also oxidoreductases may be immobilised on a hygroscopic carrier, which will actively bring oxidoreductases and malodorous compound dissolved e.g. in urine together. Also as moisture is a common condition for microbial proliferation this may ensure that moisture and microorganisms are brought in contact with oxidoreductases in the animal litter composition. Accordingly, when reference is made to "an oxidoreductase" this will in general be understood to include combinations of one or more oxidoreductases. It is to be understood that oxidoreductase variants (produced, for example, by recombinant techniques) are included within the meaning of the term "oxidoreductase" . The term "oxidoreductase", as used herein, denotes an enzyme classified as EC 1.-.-.- according to Recommendations (1992) of the Nomenclature Commi ttee of the International Union of Biochemistry and Molecular Biology, Academic Press, Inc., 1992, i.e. any enzyme classified as EC 1.1 (acting on the CH-OH group of donors) , EC 1.2 (acting on the aldehyde or oxo group of donors), EC 1.3 (acting on the CH-CH group of donors), EC 1.4 (acting on the CH-NH 2 group of donors), EC 1.5 (acting on the CH-NH group of donors), EC 1.6 (acting on NADH or NADPH) , EC 1.7 (acting on other nitrogenous compounds as donors), EC 1.8 (acting on a sulfur group of donors) , EC 1.9 (acting on a heme group of donors) , EC 1.10 (acting on diphenols and related substances as donors), EC 1.11 (acting on a peroxide as acceptor), EC 1.12 (acting on hydrogen as donor), EC 1.13 (acting on single donors with incorporation of molecular oxygen (oxygenases) , EC 1.14 (acting on paired donors with incorporation of molecular oxygen), EC 1.15 (acting on superoxide radicals as acceptor), EC 1.16 (oxidizing metal ions), EC 1.17 (acting on -CH 2 - groups), EC 1.18 (acting on reduced ferredoxin as donor), EC 1.19 (acting on reduced flavodoxin as donor), and EC 1.97 (other oxidoreductases). Preferably the oxidoreductase used in the composition of the invention is an isolated and/or purified enzymes obtained from fermenting a suitable microorganism. Preferred oxidoreductases in the context of the invention are any peroxidase belonging to the classification group EC 1.11.1.-, any laccase belonging to EC 1.10.3.2, any catechol oxidase belonging to EC 1.10.3.1, any bilirubin oxidase belonging to EC 1.3.3.5 or any monophenol monooxygenase belonging to EC 1.14.99.1 or any oxidases belonging to EC 1.1.3.-. Laccase and laccase related enzymes Preferred laccase enzymes and/or laccase related enzymes are enzymes of microbial origin. The enzymes may be derived from plants, bacteria or fungi (including filamentous fungi and yeasts) . Suitable examples from fungi include a laccase derivable from a strain of Aspergillus, Neurospora , e.g., N. crassa, Podospora, Botrytis , Collybia, Fomes, Lentinus , Pleurotus, Trametes, e.g., T. villosa and T. versicolor, Rhizoctonia, e.g., R . solani , Coprinus , e.g., C. cinereus, C. comatus, C. friesii , and C. plicatilis, Psathyrella, e.g., P. condelleana, Panaeolus, e.g., P. papilionaceus, Myceliophthora, e.g., M. thermophila, Schytalidiu , e.g., S. thermophilum, Polyporus, e.g., P. pinsi tus, Phlebia, e.g., P. radi ta (WO 92/01046), or Coriolus, e.g., C. hirsutus (JP 2-238885). Suitable examples from bacteria include a laccase derivable from a strain of Bacillus . A laccase derived from Coprinus, Myceliophthora , Polyporus, Scytalidi um or Rhizoctonia is preferred; in particular a laccase derived from Coprinus cinereus, Myceliophthora thermophila, Polyporus pinsi tus, Scytalidium thermophilum or Rhizoctonia solani . The laccase or the laccase related enzyme may furthermore be one which is producible by a method comprising cultivating a host cell transformed with a recombinant DNA vector which carries a DNA sequence encoding said laccase as well as DNA sequences encoding functions permitting the expression of the DNA sequence encoding the laccase, in a culture medium under conditions permitting the expression of the laccase enzyme, and recovering the laccase from the culture. Determination of Laccase Activity (LACU) Laccase activity, preferable laccases derivable from a strains of Polyporus , may be determined from the oxidation of syringaldazin under aerobic conditions. The violet colour produced is photometered at 530 nm. The analytical conditions are 19 mM syringaldazin, 23 mM acetate buffer, pH 5.5, 30°C, 1 min. reaction time. 1 laccase unit (LACU) is the amount of enzyme that catalyses the conversion of 1.0 μmole syringaldazin per minute at these conditions. Determination of Laccase Activity (LAMU) Laccase activity may be determined from the oxidation of syringaldazin under aerobic conditions. The violet colour produced is measured at 530 nm. The analytical conditions are 19 mM syringaldazin, 23 mM Tris/maleate buffer, pH 7.5, 30°C, 1 min. reaction time. 1 laccase unit (LAMU) is the amount of enzyme that catalyses the conversion of 1.0 μmole syringaldazin per minute at these conditions. The use of Laccases for incorporation in animal litter compositions benefits from the fact that laccases may utilize abundant molecular oxygen directly as oxidant . Peroxidases and Compounds possessing Peroxidase Activity Compounds possessing peroxidase activity may be any peroxidase enzyme comprised by the enzyme classification (EC 1.11.1.7), or any fragment derived there from, exhibiting per- oxidase activity. In the context of this invention, compounds possessing peroxidase activity comprise peroxidase enzymes and peroxidase active fragments derived from cytochromes, haemoglobin or peroxidase enzymes . Preferably, the peroxidase employed in the method of the invention is producible by plants (e.g. horseradish or soybean peroxidase) or microorganisms such as fungi or bacteria. Some preferred fungi include strains belonging to the subdivision Deuteromycotina, class Hyphomycetes , e.g., Fusari - um, Humicola , Trichoderma, Myrothecium, Verticillum, Arthromy- ces, Caldariomyces, Ulocladium, Embellisia , Cladosporium or Dreschlera , in particular Fusarium oxysporum (DSM 2672), Humicola insolens, Trichoderma resii , Myrothecium verrucaria (IFO 6113) , Verticillum alboatrum, Verticillum dahlie, Arthromyces ramosus (FERM P-7754), Caldariomyces fumago, Ulocladium chartarum, Embellisia alii or Dreschlera halodes . Other preferred fungi include strains belonging to the subdivision Basidiomycotina , class Basidiomycetes, e.g., Coprinus, Phanerochaete , Coriolus or Trametes , in particular Coprinus cinereus f. microsporus (IFO 8371), Coprinus macrorhizus, Phanerochaete chrysosporium (e.g. NA-12) or Trametes (previously called Polyporus) , e.g., T. versicolor (e.g. PR4 28-A) . Further preferred fungi include strains belonging to the subdivision Zygomycotina , class Mycoraceae, e.g., Rhizopus or Mucor, in particular Mucor hiemalis . Some preferred bacteria include strains of the order Ac tinomyce tales , e.g. Streptomyces spheroides (ATTC 23965), Strep tomyces thermoviolaceus (IFO 12382) or Streptoverticillum verticillium ssp. verticillium. Other preferred bacteria include Bacillus pumilus (ATCC 12905) , Bacillus stearothermophilus , Rhodobacter sphaeroides , Rhodomonas palustri , Streptococcus lactis, Pseudomonas purrocinia (ATCC 15958) or Pseudomonas fluorescens (NRRL B-ll) . Further preferred bacteria include strains belonging to Myxococcus , e.g., M. virescens . The peroxidase may furthermore be one which is producible by a method comprising cultivating a host cell transformed with a recombinant DNA vector which carries a DNA sequence encoding said peroxidase as well as DNA sequences encoding functions permitting the expression of the DNA sequence encoding the peroxidase, in a culture medium under conditions permitting the expression of the peroxidase and recovering the peroxidase from the culture. Particularly, a recombinantly produced peroxidase is a peroxidase derived from a Coprinus sp . , in particular C. macrorhizus or C. cinereus according to WO 92/16634. Haloperoxidases such as chromo-, bromo- and/or iodoperoxidases are particularly suitable and preferred for incorporation in animal litter compositions. Haloperoxidases form a class of enzymes which are able to oxidize halides (C1-, Br-, I-) in the presence of hydrogen peroxide or a hydrogen peroxide generating system to the corresponding hypohalous acids according to : H 2 0 2 + X- + H+ -> H 2 0 + HOX If a convenient nucleophilic acceptor is present, a reaction will occur with HOX and a halogenated compound will be formed . There are three types of haloperoxidases, classified according to their specificity for halide ions: chloroperoxidases (E.C. 1.11.1.10) which catalyse formation of hypo-chlorit from chloride ions, hypo-bromit from bromide ions and hypo-iodit from iodide ions; bromoperoxidases which catalyse formation of hypo-bromit from bromide ions and hypo-iodit from iodide ions; and iodoperoxidases (E.C. 1.11.1.8) which solely catalyze the formation of hypoiodit from iodide ions. However, hypoiodit undergoes spontaneous disproportionation to iodine and thus, iodine is usually the observed product of the reaction. These hypo-halit compounds may subsequently react with other ■ compounds forming halogenated compounds . Haloperoxidases have been isolated from various organisms: mammals, marine animals, plants, algae, a lichen, fungi and bacteria (for reference see Biochimica et Biophysica Acta 1161, 1993, pp. 249-256). It is generally accepted that haloperoxidases are the enzymes responsible for the formation of halogenated compounds in nature, although other enzymes may be involved. Haloperoxidases have been isolated from many different fungi, in particular from the fungus group dematiaceous hypho- mycetes, such as Caldariomyces, e . g. , C. fumago, Al ternaria, Curvularia, e . g. , C. verruculosa and C. inaequalis, Drechslera, Ulocladium and Botrytis (see US Patent No. 4,937,192). According to the present invention a haloperoxidase obtainable from Curvularia, in particular C. verruculosa is preferred such as C. verruculosa CBS 147.63 or C. verruculosa CBS 444.70. Curvularia haloperoxidase and recombinant production hereof is described in WO 97/04102. Haloperoxidases have also been isolated from bacteria such as Pseudomonas, e . g. , P. pyrrocinia (for reference see The Journal of Biological Chemistry 263, 1988, pp. 13725-13732) and Strep tomyces, e . g. , S. aureofaciens (for reference see Structural Biology 1, 1994, pp. 532-537) . Bromide peroxidase has been isolated from algae (see US Patent No. 4,937,192) . In a preferred embodiment the haloperoxidase is derivable from Curvularia sp., in particular C. verruculosa and C. inaequalis . In a preferred embodiment the haloperoxidase is a vanadium haloperoxidase derivable from a strain of Curvularia inaequalis such C. inaequalis CBS 102.42 as described in WO 95/27046, e.g. a vanadium haloperoxidase encoded by the DNA sequence of WO 95/27046, figure 2 all incorporated by reference . In another preferred embodiment the haloperoxidase is a vanadium haloperoxidase derivable from a strain selected from Drechslera hartlebii , Dendryphiella salina, Phaeotrichoconis crotalarie and Geniculosporium sp . The vanadium haloperoxidase is more preferably derivable from Drechslera hartlebii (DSM Ace. No. DSM 13444), Dendryphiella salina (DSM Ace. No. DSM 13443), Phaeotrichoconis crotalarie (DSM Ace. No. DSM 13441) and Geniculosporium sp . (DSM Ace. No. DSM 13442) such as described in the co-pending Danish patent applications PA2000 00628, PA 2000 00627, PA2000 00625 and PA2000 00626 all incorporated by reference. Determination of Peroxidase Activity (POXU) One peroxidase unit (POXU) is the amount of enzyme which under the following conditions catalyze the conversion of 1 μmole hydrogen peroxide per minute: 0.1 M phosphate buffer pH 7.0 , 0.88 mM hydrogen peroxide, 1.67 mM 2 , 2 ' -azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) and 30°C. The reaction is followed for 60 seconds (15 seconds after mixing) by the change in absorbance at 418 nm, which should be in the range 0.15 to 0.30. For calculation of activity is used an absorption coefficient of oxidized ABTS of 36 mM "1 cm "1 and a stoichiometry of one μmole H 2 0 2 converted per two μmole ABTS oxidized. A suitable amount of oxidoreductase to be incorporated in an animal litter composition will generally depend on the oxidoreductase, but typically an amount between about 0.01 to about 1000 mg enzyme protein per kg composition, preferably 0.1-100 mg/kg, e.g. 0.1-50 mg/kg or 0.2-10 mg/kg will be suitable. The action, e.g. antimicrobial action, oxidation etc., of an oxidoreductase requires the presence of an oxidising agent which acts as an electron donor. A suitable choice of oxidizing agent depends on the type of oxidoreductase. If the oxidoreductase is a laccase or a laccase related enzyme the oxidizing agent may be molecular oxygen available from the atmosphere. If the oxidoreductase is a peroxidase or a compound having peroxidase activity the oxidizing agent is suitably a peroxo compound in particular hydrogen peroxide or a source of hydrogen peroxide (a hydrogen peroxide precursor) which provide for in si tu production of hydrogen peroxide, e.g., percarbonate or perborate compounds or a peroxycarboxylic acid or a salt thereof, or it may be a hydrogen peroxide generating enzyme system, such as an oxidase and its substrate. Useful oxidases may be, a glucose oxidase, a glycerol oxidase or an amino acid oxidase. An example of an amino acid oxidase is given in WO 94/25574. It may be advantageous to use enzymatically generated hydrogen peroxide, since this source results in a relatively low concentration of hydrogen peroxide under the biologically relevant conditions. Low concentrations of hydrogen peroxide result in an increase in the rate of peroxidase-catalysed reaction. The oxidizing agent in this case may suitably be present in the animal litter composition in an amount corresponding to levels from 0.001-500 millimole/kg, particularly to levels from 0.01-100 millimole/kg such as 0.01-25 millimole/kg. Other useful components which may be included in the animal litter compositions to further increase the action of the oxidoreductase are enhancers or oxidoreductase enhancing agents. It is believed that these compounds act as intermediate electron acceptors which may be oxidized by the oxidising agent to form a reactive radical in a reaction catalysed by the oxidoreductase and that this reactive radical have potent antimicrobial properties. Accordingly enhancers which may be used in the animal litter compositions to enhance the antimicrobial effect include organic enhancers and inorganic enhancers. Various organic enhancers acting as electron donors for oxidoreductases for various purposes are known to the art (e.g. from WO 94/12620, WO 94/12621, WO 95/01626 and WO 96/00179) and may suitably be employed in accordance with this invention. One group of preferred organic enhancers is phenolic compounds (alkylsyringates) of the formula: Formula I wherein the letter A in said formula denotes be a group such as -D, -CH=CH-D, -CH=CH-CH=CH-D, -CH=N-D, -N=N-D, or -N=CH-D, in which D is selected from the group consisting of -CO-E, -S0 2 -E, -N-XY, and -N + -XYZ, in which E may be -H, -OH, -R, or -OR, and X and Y and Z may be identical or different and selected from - H and -R; R being a C^C^ alkyl, preferably a C^C g alkyl, which alkyl may be saturated or unsaturated, branched or unbranched and optionally substituted with a carboxy, sulpho or amino group; and B and C may be the same or different and selected from C m H 2rn+1 , where m = l, 2, 3, 4 or 5. In the above mentioned formula A may be placed meta to the hydroxy group instead of being placed in the para-position as shown. In particular embodiments of the invention the enhancer is selected from the group having the formula: Formula II in which A is a group such as -H, -OH, -CH 3 , -OCH 3 , -O (CH 2 ) n CH 3 _ where n = l, 2, 3, 4, 5, 6, 7 or 8. Such enhancers may suitably be present in the animal litter composition in amount between 0.00001-500 millimole/kg, preferably 0.0001-5 millimole/kg, e.g. 0.001-0.050 millimole/kg . Another preferred group of well performing organic enhancers comprises a -CO-NOH- group and have the following formula : Formula III in which A is Formula IV and B is the same as A, or B is H, or C1-C16 branched or unbranched alkyl wherein said alkyl may contain hydroxy, ether or ester groups, and R2 , R3 , R4 , R5 and R6 are H, OH, NH2 , COOH, S03H, C1-C12 branched or unbranched alkyl, acyl, N02 , CN, CI, CF3, NOH-CO-phenyl, C1-C6-CO-NOH-A, CO-NOH-A, COR12, phenyl-CO-NOH-A, OR7 , NR8R9, COOR10, or NOH-CO-R11, wherein R7 , R8, R9, RIO and Rll are C1-C12 branched or unbranched alkyl or acyl . Within this group of enhancers particularly preferred enhancers are selected from the group consisting of 4-nitrobenzoic acid-N-hydroxyanilide; 4-methoxybenzoic acid-N-hydroxyanilide; N,N' -dihydroxy-N, N' -diphenylterephthalamide; decanoic acid-N-hydroxyanilide; N-hydroxy-4 -cyanoacetanilide ; N-hydroxy-4-acetylacetanilide; N-hydroxy-4-hydroxyacetanilide; N-hydroxy-3- (N' -hydroxyacetamide) acetanilide; 4-cyanobenzoic acid-N-hydroxyanilide; N-hydroxy-4 -nitroacetanilide ; and N-hydroxyacetanilide . These enhancers may suitably be present in the animal litter composition in concentrations from 1 to 1000 micromole/kg, preferably from 5 to 500 micromole/kg. The enhancer may also be one of the compounds disclosed in WO 96/18770 such as N-hydroxy compounds, in particular aliphatic, cycloaliphatic , heterocyclic or aromatic compounds containing NO-, N(0H)-, or N(OH) (R 1 ) , especially N-hydroxy benzotriazol (HOBT) , Violuric acid, or N-hydroxyacetanilide (HAA) . In a preferred embodiment of the invention the enhancer is a compound of the general formula (V) : Formula V wherein R 1 , R 2 , R 3 , R 4 are individually selected from the group consisting of hydrogen, halogen, hydroxy, formyl , carboxy and salts and esters thereof, amino, nitro, C 1 -C 12 alkyl, C x -C 6 alkoxy, carbonyl (C 1 -C 12 alkyl), aryl, in particular phenyl , sulpho, aminosulfonyl , carbamoyl, phosphono, phosphonooxy, and salts and esters thereof, wherein the R 1 , R 2 , R 3 , R 4 may be substituted with R 5 , wherein R s represents hydrogen, halogen, hydroxy, formyl, carboxy and salts and esters thereof, amino, nitro, C^C^ alkyl, C j -C 8 alkoxy, carbonyl (C 1 -C 12 alkyl), aryl, in particular phenyl, sulpho, aminosulfonyl , carbamoyl, phosphono, phosphonooxy, and salts and esters thereof, [X] represents a group selected from (-N=N-), (-N=CR 6 -) m , (-CR 6 =N- ) ra , (-CR 6 =CR 7 -) m , (-CR 6 =N-NR 7 -) , ( -N=N-CHR 6 - ) , ( -N=CR 6 -NR 7 - ) , (- N=CR 6 -CHR 7 -) , (-CR 6 =N-CHR 7 -) , ( -CR 6 =CR 7 -NR 8 - ) , and ( -CR 6 =CR 7 -CHR 8 - ) , wherein R s , R 7 , and R 8 independently of each other are selected from H, OH, NH 2 , COOH, S0 3 H, C^-al yl, N0 2 , CN, CI, Br, F, CH 2 0CH 3 , 0CH 3 , C00CH 3 ; and m is 1 or 2. In a more preferred embodiment of the invention the enhancer is a compound of the general formula (VI) : Formula VI wherein R 1 , R 2 , R 3 , R 4 are individually selected from the group consisting of hydrogen, halogen, hydroxy, formyl, carboxy and salts and esters thereof, amino, nitro, C 1 -C 12 alkyl, alkoxy, carbonyl (C 1 -C 12 alkyl), aryl, in particular phenyl, sulpho, aminosulfonyl , carbamoyl, phosphono, phosphonooxy, and salts and esters thereof, wherein the R 1 , R 2 , R 3 , R 4 may be substituted with R 5 , wherein R 5 represents hydrogen, halogen, hydroxy, formyl , carboxy and salts and esters thereof, amino, nitro, alkoxy, carbonyl (C 1 -C 12 alkyl), aryl, in particular phenyl, sulpho, aminosulfonyl , carbamoyl, phosphono, phosphonooxy, and salts and esters thereof. The enhancer may also be a salt or an ester of formula V or VI. Further preferred enhancers are oxoderivatives and N- hydroxy derivatives of heterocyclic compounds and oximes of oxo- and formyl -derivatives of heterocyclic compounds, said heterocyclic compounds including five-membered nitrogen- containing heterocycles, in particular pyrrol, pyrazole and imidazole and their hydrogenated counterparts (e.g. pyrrolidine) as well as triazoles, such as 1 , 2 , 4-triazole; six- membered nitrogen-containing heterocycles, in particular mono-, di- and triazinanes (such as piperidine and piperazine) , morpholine and their unsaturated counterparts (e.g. pyridine and pyrimidine) ; and condensed heterocycles containing the above heterocycles as substructures, e.g. indole, benzothiazole, quinoline and benzoazepine . Examples of preferred enhancers from these classes of compounds are pyridine aldoximes; N-hydroxypyrrolidinediones such as N-hydroxysuccinimide and N-hydroxyphthalimide; 3,4- dihydro-3-hydroxybenzo [1,2,3] triazine-4-one; formaldoxime trimer (N,N' , ' ' -trihydroxy-1 , 3 , 5-triazinane) ; and violuric acid (1 , 3-diazinane-2 , 4 , 5 , 6-tetrone-5-oxime) . Still further enhancers which may be applied in the invention include oximes of oxo- and formyl -derivatives of aromatic compounds, such as benzoquinone dioxime and salicylaldoxime (2-hydroxybenzaldehyde oxime) , and N- hydroxyamides and N-hydroxyanilides, such as N- hydroxyacetanilide . Preferred enhancers are selected from the group consisting of 1-hydroxybenzotriazole; 1-hydroxybenzotriazole hydrate; 1-hydroxybenzotriazole sodium salt; 1- hydroxybenzotriazole potassium salt; 1-hydroxybenzotriazole lithium salt; 1-hydroxybenzotriazole ammonium salt; 1- hydroxybenzotriazole calcium salt; 1-hydroxybenzotriazole magnesium salt; and 1-hydroxybenzotriazole- 6 -sulphonic acid. A particularly preferred enhancer is 1- hydroxybenzotriazole. All the specifications of N-hydroxy compounds above are understood to include tautomeric forms such as N-oxides whenever relevant . In particular, the enhancer of the invention may be the corresponding N-oxyl free radical to any of the compounds disclosed in WO 96/18770 such as TEMPO (2,2,6,6- tetramethylpiperidinoxyl) . These organic enhancers may suitably be present in the litter composition in concentrations from 1 to 1000 micromole/kg, preferably from 5 to 500 micromole/kg. Inorganic enhancers may also be relevant. Especially when using haloperoxidases for animal litter compositions presence of inorganic halide ions such as chloride, bromide and/or iodide may enhance the antimicrobial effect of the haloperoxidase. Suitable ranges of chloride ions are 0.05 - 500 millimole/kg and suitable ranges of bromide and/or iodide ions are 0.01 - 100 millimole/kg. We have further observed that an improved anti- microbial or preservation effect may be obtained using an ammonium enhancer, preferably in combination with a halide enhancer or an organic enhancer. The ammonium enhancer may be compounds of the formula: Formula VII HN s S R2 wherein the substituent groups Rl and R2 may be identical or different. Rl and R2 may suitably be any of the following groups: hydrogen, halide, sulphate, phenyl, a straight or branched chain alkyl having from 1 to 14 carbon atoms, or a substituted straight or branched alkyl group having from 1 to 14 carbon atoms where the substituent group is located at C 1 -C 14 and represent any of the following radicals: hydroxy, halogen, formyl , carboxy, carboxy esters, carboxy salts, carbamoyl, sulfo, sulfo esters, sulfo salts, sulfamoyl, nitro, amino, phenyl, C 1 -C 5 -alkoxy, carbonyl -C^C,;-alkyl , aryl -C 1 -C 5 -alkyl . Where Rl and/or R2 includes groups selected from carbamoyl, sulfamoyl, and amino groups these groups may furthermore be un- substituted or substituted once or twice with a substituent group R3 , Where Rl and/or R2 includes a phenyl group it may furthermore be unsubstituted or substituted with one or more substituent groups R3. Where Rl and/or R2 includes groups selected from C 1 -C 5 -alkoxy, carbonyl -C 1 -C 5 -alkyl , and aryl-C^C,;- alkyl these groups may be saturated or unsaturated, branched or unbranched, and may furthermore be unsubstituted or substituted with one or more substituent groups R3. R3 represents any of the following groups: halogen, hydroxy, formyl , carboxy, carboxy esters, carboxy salts, carbamoyl, sulfo, sulfo esters, sulfo salts, sulfamoyl, nitro, amino, phenyl, aminoalkyl, piperidino, piperazinyl, pyrrolidin-1-yl , C 1 -C 5 -alkyl, C 1 -C 3 - alkoxy. Where R3 includes groups selected from carbamoyl, sulfamoyl, and amino these groups may furthermore be unsubstituted or substituted once or twice with hydroxy, C^C, ; - alkyl, C 1 -C 5 -alkoxy . Where R3 includes phenyl this group may furthermore be substituted with one or more of the following groups: halogen, hydroxy, amino, formyl , carboxy, carboxy esters, carboxy salts, carbamoyl, sulfo, sulfo esters, sulfo salts, and sulfamoyl. Where R3 includes groups selected from C x - C 5 -alkyl, and C^Cs-alkoxy these groups may furthermore be saturated or unsaturated, branched or unbranched, and may furthermore be substituted once or twice with any of the following radicals: halogen, hydroxy, amino, formyl , carboxy, carboxy esters, carboxy salts, carbamoyl, sulfo, sulfo esters, sulfo salts, and sulfamoyl. Rl and R2 may also suitably together a group -B-, in which B represents any of the following groups: (-CHR3-N=N- ) , (-CH=CH-) n or (-CH=N-) n in which groups n-represents an integer of from 1 to 3 and R3 is a substituent group as defined, supra . (It is to be understood that if the above mentioned formula comprises two or more R3- substituent groups, these R3 -substituent groups may be the same or different) . As used herein, the ammonium enhancer may be in their cationic form. In a preferred embodiment Rl is hydrogen. In another preferred embodiment Rl is hydrogen and R2 is an alcohol (amino alcohol), e.g., ethanol amine . In a further preferred embodiment the ammonium enhancer is an ammonium salt, i.e. any ammonium salt known in the art: e.g., diammonium sulphate, ammonium chloride, ammonium bromide, or ammonium iodide. The ammonium enhancer may suitably be present in the litter composition of the invention in a concentration corresponding to an ammonium concentration in the range of from 0.01-1000 millimole/kg, preferably in the range of from 0.05-500 millimole/kg. Other enzymes Conventionally other enzymes have been disclosed as desirable components for the purpose of cleaning and for destroying animal excretions, including regurgitated. Enzymes other than ureases can be used to destroy the soils, such as hydrolase and/or a combination of hydrolases . In a preferred embodiment, the hydrolase to be used is selected from the group consisting of glucosidases, i.e. cellulases (endoglucanases, cellobiohydrolases, β-glucosidases) , hemicellulases (xylanases, mannanases, xylan acetyl esterases)), pectinases (arabinanases, α-arabino-furanosidases, galactanases, pectin lyases, pectin methyl esterases, polygalacturonases, rhamnogalacturonan acetyl esterases, rhamnogalacturonases) , amylases; proteases, and lipases . The hydrolases to be used may be selected according to the properties or a combination of several hydrolases having different enzyme activities may be used. Nonlimiting examples of specific enzymes useful in animal litter compositions are: 1 , 2-1 , 3 -α-D-mannan mannohydrolase, 1, 3-β-D-xylan xylanohydrolase, 1 , 3 -β-D-glucan glucanohydrolase, 1, 3 (1, 3; 1,4) -α-D-glucan 3 -glucanohydrolase, 1 , 3 (1 , 3 ; 1 , 4) -β-D- glucan 3 (4) -glucanohydrolase, 1 , 3-1 , 4 -α-D-glucan 4- glucanohydrolase, 1 , 4 -α-D-glucan glucanehydrolase, 1,4 -α-D- glucan glucohydrolase, 1 , 4- (1, 3 : 1, 4) -β-D-glucan 4- glucanohydrolase, 1 , 4 -β-D-glucan glucohydrolase, 1 , 4-β-D-xylan xylanohydrolase, 1 , 4-β-D-mannan mannanohydrolase, 1,5-α-L- arabinan 1 , 5-α-L-arabinanohydrolase, 1 , 4 -α-D-glucan maltohydrolase, 1 , 6 -α-D-glucan 6 -glucanohydrolase, 2,6-β-D- fructan fructanohydrolase, α-Dextrin 6-glucanohydrolase, α-D- galactoside galactohydrolase, α-D-glucoside glucohydrolase, α- D-mannoside mannohydrolase, acylneuraminyl hydrolase, Aero acter-capsular-polysaccharide galactohydrolase , β-D-fructofuranoside fructohydrolase, β-D-fucoside fucohydrolase, β-D-fructan fructohydrolase, β-D-galactoside galactohydrolase, β-D-glucoside glucohydrolase, β-D-glucuronoside, glucuronosohydrolase, β-D-mannoside mannohydrolase, β-N-acetyl-D-hexosaminide N-acetylhexosamino hydrolase, cellulose-sulfate sulfohydrolase, collagenase, dextrin 6-α-D-glucanohydrolase, glycoprotein- phosphatidylinositol phosphatidohydrolase, hyaluronate 4- glycanohydrolase, hyaluronoglucuronidase, pectin pectylhydrolase, peptidoglycan N-acetylmuramoylhydrolase, phosphatidylcholine 2-acylhydrolase, phosphatidylcholine 1- acylhydrolase, poly (1, 4-α-D-galacturonide) , poly(l,4-(N- acetyl-β-D-glucosaminide) ) -glycanohydrolase, proteases, sucrose α-glucosidase, triacylglycerol acylhydrolase, triacylglycerol protein-acylhydrolase . A particularly useful hydrolytic enzyme for incorporation in an animal litter composition is any enzyme having proteolytic activity. Thus, the enzyme may be a proteolytic enzyme of plant origin, e.g. papain, bromelain, ficin, or of animal origin, e.g. trypsine and chymotrypsine, or of microbial origin, i.e. bacterial or fungal origin or from yeasts. It is to be understood that any mixture of various proteolytic enzyme may be applicable in an animal litter composition. In a preferred embodiment of the invention, the proteolytic enzyme is a serine-protease, a metallo-protease, or an aspartate-protease . A serine protease is an enzyme which catalyzes the hydrolysis of peptide bonds, and in which there is an essential serine residue at the active site. They are inhibited by diisopropylfluorophosphate, but in contrast to metalloproteases, are resistant to ethylene diamino tetraacetic acid (EDTA) (although they are stabilized at high temperatures by calcium ions) . They hydrolyze simple terminal esters and are similar in activity to eukaryotic chymotrypsin, also a serine protease. A more narrow term, alkaline protease, covering a sub-group, reflects the high pH optimum of some of the serine proteases, from pH 9.0 to 11.0 The serine proteases usually exhibit maximum proteolytic activity in the alkaline pH range, whereas the metallo-proteases and the aspartate-proteases usually exhibit maximum proteolytic activity in the neutral and the acidic pH range, respectively. A sub-group of the serine proteases are commonly desig- nated as subtilisins. A subtilisin is a serine protease produced by Gram-positive bacteria or fungi. The amino acid sequence of a number of subtilisins have been determined, including at least six subtilisins from Bacillus strains, namely, subtilisin 168, subtilisin BPN, subtilisin Carlsberg, subtilisin DY, subtilisin amylosacchariticus, and mesentericopeptidase, one subtilisin from an actinomycetales, thermitase from Thermoactinomyces vulgar is , and one fungal subtilisin, proteinase K from Tri tirachium album. A further subgroup of the subtilisins, subtilases, have been recognised more recently. Subtilases are described as highly alkaline subtilisins and comprise enzymes such as subtilisin PB92 (MAXACAL ® , Gist-Brocades NV) , subtilisin 309 (SAVINASE ® , NOVO NORDISK A/S) , and subtilisin 147 (ESPERASE ® , NOVO NORDISK A/S) . In the context of this invention, a subtilisin variant or mutated subtilisin protease means a subtilisin that has been produced by an organism which is expressing a mutant gene derived from a parent microorganism which possessed an original or parent gene and which produced a corresponding parent enzyme, the parent gene having been mutated in order to produce the mutant gene from which said mutated subtilisin protease is produced when expressed in a suitable host . These mentioned subtilisins and variants thereof constitute a preferred class of proteases which are useful in the method of the invention. An example of a useful subtilisin variant is a variant of 5 subtilisin 309 (SAVINASE * ) wherein, in position 195, glycine is substituted by phenylalanine (G195F or 195 Gly to 195 Phe) . Conveniently, conventional fermented commercial proteases are useful . Examples of such commercial proteases are Alcalase (produced by submerged fermentation of a strain of Bacillus li - •lo cheniformis) , Esperase (produced by submerged fermentation of an alkalophilic species of Bacillus) , Rennilase ® (produced by submerged fermentation of a non-pathogenic strain of Mucor mie- hei ) , Savinase ® (produced by submerged fermentation of a genetically modified strain of Bacillus) , e.g. the variants is disclosed in the International Patent Application published as WO 92/19729, and Durazym (a protein-engineered variant of Sa- vinase 8 ) . Also Everlase ® and Kannase ® are useful. All the mentioned commercial proteases are produced and sold by Novo Nor- disk A/S, DK-2880 Bagsvaerd, Denmark. Further useful commercial 20 proteases are MAXATASE ® from International Bio-Synthetics, Inc. (The Netherlands) and proteases made by Genencor International, Inc., according to one or more ofthe following patents: Caldwell et al , U.S. Patent Nos. 5,185,258, 5,204,015 and 5,244,791, e.g. Properase ® . 25 Other preferred serine-proteases are proteases from Nocardiopsis, Aspergillus, Rhizopus, Bacillus alcalophilus, B . cereus, N. natto, B . vulgatus, B . mycoide, and subtilins from Bacillus , especially proteases from the species Nocardiopsis sp . and Nocardiopsis dassonvillei such as those disclosed in 30 the International Patent Application published as WO 88/03947, especially proteases from the species Nocardiopsis sp . , NRRL 18262, and Nocardiopsis dassonvillei , NRRL 18133. Yet other preferred proteases are the serine proteases from mutants of Bacillus subtilins disclosed in the International Patent 35 Application No. PCT/DK89/00002 and in the International Patent Application published as WO 91/00345, and the proteases disclosed in EP 415 296. Another preferred class of proteases are the metallo-pro- teases of microbial origin. Conveniently, conventional fer- mented commercial proteases are useful . Examples of such a commercial protease is Neutrase (Zn) (produced by submerged fermentation of a strain of Bacillus subtilis) , which is produced and sold by Novo Nordisk A/S, DK-2880 Bagsvaerd, Denmark . Other useful commercial protease enzyme preparation are Bactosol ® WO and Bactosol ® SI, available from Sandoz AG, Basle, Switzerland; Toyozyme ® , available from Toyo Boseki Co. Ltd., Japan; and Proteinase K ® (produced by submerged fermentation of a strain of Bacillus sp . KSM-K16) , available from Kao Corporation Ltd., Japan. Still other proteases include Protease A (see European Patent Application 130,756, published January 9, 1985); Protease B (see European Patent Application Serial No. 87303761.8, filed April 28, 1987, and European Patent Application 130,756, Bott et al, published January 9, 1985) Another hydrolytic enzyme which may be useful for incorporation in animal litter is a microbial lipase. As such, the lipase may be selected from yeast, e.g. Candida, lipases, bacterial, e.g. Pseudomonas or Bacillus, lipases; or fungal, e.g. Humicola or Rhizomucor, lipases. More specifically, suitable lipases may be the Rhizomucor miehei lipase (e.g. prepared as described in EP 238 023), Thermomyces lanuginosa lipase e.g. prepared as described in EP 305 216 (available from Novo Nordisk under the trade name Lipolase™) , Humicola insolens lipase, Pseudomonas stutzeri (eg. ATCC 19.154) lipase, Pseudomonas cepacia lipase, Candida antarctica lipase A or B, or lipases from rGPL, Absidia blakesleena, Absidia corymbifera, Fusarium solani , Fusarium oxysporum, Penicillum cyclopium, Penicillum crustosum, Penicillum expansum, Rhodotorula glutinis, Thiarosporella phaseolina, Rhizopus microsporus, Sporobolomyces shibatanus , Aureobasidium pullulans, Hansenula anomala, Geotricum penicillatum, Lactobacillus curvatus, Brochothrix thermosoha ta, Coprinus cinerius, Trichoderma harzanium, Trichoderma reesei , Rhizopus japonicus or Pseudomonas plantar i . Other examples of suitable lipases may be variants of any one of the lipases mentioned above, e.g. as described in WO 92/05249 or WO 93/11254. Also suitable lipase enzymes for usage herein include those described in Japanese Patent Application 53,20487, laid open to public inspection on February 24, 1978. This lipase is available from Amano Pharmaceutical Co. Ltd., Nagoya, Japan, under the trade name Lipase P "Amano," herinafter referred to as "Amano-P." Other commercial lipases include Amano-CES, lipases ex Chromobacter viscosum, e.g. Chromobacter viscosum var. lipolyticum NRRLB 3673, commercially available from Toyo Jozo Co., Tagata, Japan; and further Chromobacter viscosum lipases from U.S. Biochemical Corp., U.S.A. and Disoynth Co., The Netherlands, and lipases ex Pseudomonas gladioli . Nonlimiting examples of amylases useful for incorporation in animal litter include Bacillus amylases, e.g. Bacillus stearothermophilus amylase, Bacillus amyloliquefaciens amylase, Bacillus subtilis amylase or Bacillus licheniformis amylase (e.g. as available from Novo Nordisk under the trade name Termamyl ® ) , or Aspergillus amylases, e.g. Aspergillus niger or Aspergillus oryzae amylase. Other examples of suitable amylases may be variants of any one of the amylases mentioned above, e.g. as described in US 5,093,257, EP 252 666, WO 91/00353, FR 2,676,456, EP 285 123, EP 525 610, PCT/DK93/00230. Also the amylase RAPIDASE ® , Novo Industries may be suitable. Another useful hydrolytic enzyme is a "cellulase" or "cellulolytic enzyme" which refers to an enzyme which catalyses the degradation of cellulose to glucose, cellobiose, triose and other cello-oligosaccharides . Preferably, the cellulase is an - endoglucanase, more preferably a microbial endoglucanase, especially a bacterial or fungal endoglucanase. Examples of bacterial endoglucanases are endoglucanases derived from or producible by bacteria from the group of genera consisting of Pseudomonas or Bacillus lautus . The cellulase or endoglucanase may be an acid, a neutral of an alkaline cellulase or endoglucanase, i.e. exhibiting maximum cellulolytic activity in the acid, neutral of alkaline range, respectively. Accordingly, a useful cellulase or endoglucanase is an acid cellulase or endoglucanase, preferably a fungal acid cellulase or endoglucanase, more preferably a fungal acid cellulase or endoglucanse enzyme with substantial cellulolytic activity at acidic conditions which is derived from or producible by fungi from the group of genera consisting of Trichoderma, Actinomyces, Myrothecium, Aspergillus, and Botrytis . A preferred useful acid cellulase or endoglucanase is derived from or producible by fungi from the group of species consisting of Trichoderma viride, Trichoderma reesei , Trichoderma longibrachiatum, Myrothecium verrucaria, Asper- gillus niger, Aspergillus oryzae, and Botrytis cinerea . Another useful cellulase or endoglucanase is a neutral or alkaline cellulase or endoglucanse, preferably a fungal neutral or alkaline cellulase or endoglucanse, more preferably a fungal alkaline cellulase or endoglucanase with substantial cellulolytic activity at alkaline conditions which is derived from or producible by fungi from the group of genera consisting of Aspergillus , Penicillium, Myceliophthora, Humicola, Irpex, Fusarium, Stachybotrys, Scopulariopsi s, Chaetomium, Mycogone, Verticillium, Myrothecium, Papulospora, Gliocladium, Cephalo- sporium and Acremonium . A preferred alkaline cellulase or endoglucanase is derived from or producible by fungi from the group of species consisting of Humicola insolens , Fusarium oxysporum, Myce- liopthora thermophile, or Cephalosporium sp . , preferably from the group of species consisting of Humicola insolens , DSM 1800, Fusarium oxysporum, DSM 2672, Myceliopthora thermophila, CBS 117.65, or Cephalosporium sp . , RYM-202. Examples of xylanases useful in the method of the present invention include enzymes having xylanolytic activity which are produced or producible by a strain selected from the group of species consisting of Humicola insolens (see e.g. WO 92/17573), Aspergillus aculeatus (an enzyme exhibiting xylanase activity, which enzyme is immunologically reactive with an antibody raised against a purified xylanase derived from Aspergillus aculeatus, CBS 101.43, see e.g. WO 94/21785), Bacillus pumilus (see e.g. WO 92/03540), Bacillus stearathermophilus (see e.g. WO 91/18976, WO 91/10724) , Bacillus sp . AC13 (especially the strain NCIMB 40482, see e.g. WO 94/01532), Trichoderma longibrachiatum and Chainia sp . (see e.g. EP 0 353 342 Al) , Thermoascus aurantiacus (see e.g. US patent 4,966,850), Trichoderma harzianum and Trichoderma reseei (see e.g. US patent 4,725,544), Aureobasidiu pullulans (see e.g. EP 0 373 107 A2) , Thermomyces lanuginosus (see e.g. EP 0 456 033 A2) , Bacillus circulans (WO 91/18978), Aspergillus oryzae (see e.g. SU 4610007), Thermomonospora fusca (see e.g. EP 0 473 545 A2), St e to-nyces lividans (see e.g. WO 93/03155), Streptomyces viridosporus (see e.g. EP 496 671 Al) , Bacillus licheniformi s (see e.g. JP 9213868) and Trichoderma longibrachiatum [see W.J.J. van den Tweel et al.(Eds.), "Stability of Enzymes" , Proceedings of an International Symposium heeld in Maastricht, The Netherlands, 22-25 November 1992, Fisk,R.S. and Simpson, pp.323-328]; or from the group of genera consisting of Thermotoga (see e.g. WO 93/19171), Rhodothermus (see e.g. WO 93/08275), Dictyoglomus (see e.g. WO 92/18612) and Streptomyces (see e.g. US patent 5,116,746). Other examples of suitable xylanases may be variants (derivatives or homologues) of any one of the above-mentioned enzymes having xylanolytic activty. A useful pectinase may be an enzyme belonging to the enzyme classes polygalacturonases (EC3.2.1.15) , pectinesterases (EC3.2.1.11) , pectin lyases (EC4.2.2.10) and hemicellulases such as endo-1, 3-b-xylosidase (EC 3.2.1.32), xylan 1,4-b- xylosidase (EC 3.2.1.37) and a-L-arabinofuranosidase (EC 3.2.1.55) . A suitable source organism for pectinases may be Aspergillus niger. In a preferred embodiment, the hydrolase enzyme (s) is/are produced by a strain of the fungus Aspergillus aculeatus, preferably Aspergillus aculeatus, CBS 101.43. It is known that this strain produces an enzyme composition comprising pectolytic and a range of hemicellulolytic enzyme activities, The hydrolase (s) are present in the cleaning composition in an amount from about 0.01 to about 5000 μg protein/g of composition, preferably from about 1 to about 500 μg protein/g of animal litter composition. Enzyme-polyethylene glycol conjugates are also preferred. Such polyethylene glycol (PEG) derivatives of enzymes, wherein the PEG or alkoxy-PEG moieties are coupled to the protein molecule through, e.g., secondary amine linkages. Suitable derivatization decreases immunogenicity, thus minimizes allergic reactions, while still maintains some enzymatic activity. An example of protease-PEG ' s is PEG-subtilisin Carlsberg from B. lichenniformis coupled to methoxy-PEGs through secondary amine linkage, and is available from Sigma- Aldrich Corp., St. Louis, Missouri. PROCESS Animal litter compositions according to the present invention can be prepared as follows. The calculated amounts of actives, i.e., enzymes and other antimicrobial and/or urease inhibitor, odour absorbing actives, and optional ingredients, e.g., perfume microcapsules, binders, and the like, are dissolved and/or suspended, in appropriate amounts of liquid carrier, preferably water, enough to sufficiently uniformly distribute the actives over the solid absorbing litter material. All actives are preferably incorporated in the same solution and/or slurry. However, the enzymes may more preferably be applied onto the solid absorbing litter material separately, e.g., by spraying it, sequentially to the animal litter, preferably with a drying step in between, as these biological molecules may be sensitive to other active ingredients in solution. The enzyme (s) may be applied as a fermentation broth, a concentrated enzyme solution, or a slurry of amorphous and/or crystalline enzyme such as described in WO 91/09943 included herein by reference. In another more preferred embodiment of the invention the enzyme (s) are added to and mixed with the animal litter compositions in the form of a conventional enzyme granule. Such granules may be prepared by methods known to the art, e.g. as - Spray dried products, wherein a liquid enzyme containing solution is atomized in a spray drying tower to form small droplets which during its way down the drying tower dries up to form an enzyme containing particulate material. Very small particles can be produced this way (Michael S. Showell (editor) ; Powdered detergents; Surfactant Science Series; 1998; vol. 71; page 140-142; Marcel Dekker) . Layered products, wherein the enzyme is coated as a layer around a preformed core particle, wherein an enzyme containing solution is atomized, typically in a fluid bed apparatus wherein the preformed core particles are fluidized, and the enzyme containing solution adheres to the core particles and dries up to leave a layer of dry enzyme on the surface of the core particle. Particles of a desired size can be obtained this way if a useful core particle of the desired size can be found. This type of product is described in eg WO 97/23606 Another type of product is known wherein an absorbing core particle is applied, and rather than coating the enzyme as a layer around the core, the enzyme is absorbed onto and/or into the surface of the core. Such a process is described in WO 97/39116. Extrusion or pelletized products, wherein an enzyme containing paste is pressed to pellets or under pressure is extruded through a small opening and cut into particles which is subsequently dried, such particles usually have a considerable size because of the material in which the extrusion opening is made (usually a plate with bore holes) sets a limit on the allowable pressure drop over the extrusion opening. Also very high extrusion pressures when using a small opening increases heat generation in the enzyme paste which is harmful to the enzyme. (Michael S. Showell (editor) ; Powdered detergents; Surfactant Science Series; 1998; vol. 71; page 140-142; Marcel Dekker) Prilled products, wherein an enzyme powder is suspended in molten wax and the suspension is sprayed, eg through a rotating disk atomizer, into a cooling chamber where the droplets quickly solidify (Michael S. Showell (editor); Powdered detergents ; Surfactant Science Series; 1998; vol. 71; page 140-142; Marcel Dekker). Mixer granulation products, wherein an enzyme containing liquid is added to a dry powder composition of conventional granulating components. The liquid and the powder in a suitable proportion is mixed in and as the moisture of the liquid is absorbed in the dry powder, the components of the dry powder will start to adhere and agglomerate and particles will build up forming granules comprising the enzyme. Such a process is described in 4,106,991 (NOVO NORDISK) and related documents EP 170360 Bl (NOVO NORDISK) , EP 304332 Bl (NOVO NORDISK) , EP 304331 (NOVO NORDISK) , WO 90/09440 (NOVO NORDISK) and WO 90/09428 (NOVO NORDISK) . Also these granular enzyme products may be prepared as so- called co-granules, wherein an oxidoreductase may be granulated together in one granule with an enhancer such as described in WO 95/33039. Also in the cases where the actives are not totally compatibles, such as in the case of cyclodextrin odour control active and an organic urease inhibitor which can form complex with the cyclodextrin, or in the case of a water-insoluble organic antimicrobial which is more effectively soluble in a solvent such as alcohol (and such organic antimicrobial can form complex with the cyclodextrin) , it is preferably that the incompatible actives are distributed. For some absorbing clay litter materials, since the water of the aqueous solutions can be absorbed quickly into the clay particles, the drying step(s) may not be necessary. For materials with low solubility the water is preferably heated to from about 40°C to about 90 °C, preferably from about 50°C to about 80 °C, more preferably from about 60 °C to about 75°C, to permit the use of the minimum amount of water, thus lowering the time and/or heat needed to dry the litter material. Such poorly soluble materials, e.g., beta- cyclodextrin, can also preferably be used in as a finely divided powder and be suspended in a suitable amount of liquid carrier (e.g., preferably, water) into a mobile and sprayable slurry, typically at a liquid carrier-to-powder ratio of from about 1:1 to about 10:1, more preferably from about 2:1 to about 5:1. Similarly, the perfume/cyclodextrin complex is preferably added as a slurry. It is convenient to use the slurry used to form the complex and add any uncomplexed cyclodextrin to that slurry, the excess cyclodextrin helping to make more efficient use of the perfume. The amount of water necessary will vary with the kind of actives and/or absorbent litter material used and typically is in the range of from about 5 ml to about 500 ml, preferably from about 8 ml to about 250 ml, more preferably from about 12 ml to about 150 ml, per kg of solid absorbing litter material. The amount of solution is preferably just sufficient to distribute the actives on the absorbing litter material . This insures quantitative deposition of the actives and eliminates the necessity of handling excess water. The solid absorbing litter material is then dried at ambient conditions, or in an oven at a temperature of from about 50°C to about 95°C. This procedure lends itself extremely well to a continuous process, whereby metered flows of solid absorbing litter material and solution (or solutions) and/or slurry (or slurries) of actives are contacted with one another (e.g., by spraying the actives in liquid carriers) , and the litter material is subsequently dried on a perforated conveyor belt and/or in an air-dry tunnel. The amount of actives, e.g., enzymes and/or other antimicrobial/urease inhibitor, odour absorbing actives, perfume, and the like, to be used depends on its effectiveness, its cost and its toxicity. However in a preferred embodiment the drying temperature is kept low, eg. under 70 °C or under 60 °C or under 50 °C to prevent heat denaturation of the enzymes. Accordingly the application of enzyme to the solid litter composition may very well be performed in a fluid bed type of equipment . Mixtures In general, the more water soluble materials which are added to the animal litter, replenishment compositions, etc., to control the formation of odor and/or absorb odor are desirable to promote spreading. Also, the less toxic materials are more desirable, since animals, and cats, especially, will tend to lick off any litter that sticks to their fur. Mixtures of the above compounds can be used. Mixtures can be more effective and, by limiting the amount of any one material, can be less toxic . Industrial Process - An animal litter in accordance with the present invention is preferably formed by spraying metered quantities of slurries onto a quantity of absorbent particles to affix the activities onto at least some of these absorbent particles in substantially intact form. The solutions and/or slurries can be pumped with a conventional metering pump and sprayed through a plurality of conventional spray nozzles onto an evenly distributed bed of absorbent particles being moved, as by a conveyor belt, past the spray nozzles. The moving bed of absorbent particles is preferably fairly thin, for example about W (1.3 cm) to about 1 1^" (3.8 cm), so that a significant number of the litter particles have affixed actives, and to aid in homogeneous dispersion of the particles with affixed actives in packaging. All percentages, ratios, and parts herein, in the specification, examples, and claims are by weight and are approximations unless otherwise stated. The following are non-limiting examples of the instant composition. Methods Determination of haloperoxidase activity Color reagent : 2.98 g potassium bromide is dissolved in a mixture of 2 ml 0.2 % Phenol Read in 96 % EtOH and 48 ml 0.3 M TRIS buffer pH 7.0 Vanadate solution: 18.4 mg sodium orthovanadate is dissolved in 10 ml de- ionized water. Hydrogen peroxide solution: 0.1 ml 30 % hydrogen peroxide is added to 9.9 ml de-ionized water. When performing the assay, the enzyme sample is pre- incubated with an amount of the Vanadate solution for a specified period of time and then specified amounts of hydrogen peroxide and the Color Rreagent is added and the activity is monitored by measuring the absorbance at 595 nm (the color changes from read to bluish violet) . Determination of smell : Evaluation of smell was performed by a test panel of three trained persons . EXAMPLES Eample 1 Experiments were performed using 10 ml. of artificial urine with pH 6.0 (Urea (300 mM) , calcium sulphate (2 mM) , magnesium sulphate (3.5 mM) , potassium chloride (60 mM) , Triton X-100 and sodium chloride (130 mM) ) . Initially, hydrogen peroxide was added to a final concentration of 1 mM and then recombinant haloperoxidase derived from Curvularia verruculosa CBS 147.63 (rHP) described in WO 97/04102 (Novo Nordisk) was added to the desired concentration. The experiments were initiated by addition of urease type III from Jack Beans (Sigma U1500) . Samples were incubated on a shaking water bath at 25°C in closed vessels. Urease activities in the samples was evaluated at given time, intervals by monitoring pH (Radiometer PHM 85, pH meter) and production of ammonia monitored by the development of the characteristic malodour. Results : This example clearly illustrates that the system of halo- peroxidase/hydrogen is capable, in a dose dependent manner, of completely inactivating urease and thereby prevent the development of malodour from the samples . EXAMPLE 2 The anti -microbial activity of Cuvularia verruculosa haloperoxidase was evaluated in artificial urine against Escherichia coli (Accession No. DSM 1576), Enterococcus faecalis (Accession No. DSM 2570) and Proteus mirabilis (Accession No. DSM 788) adhering to pulp material. The anti -microbial activity was determined as reduction in living bacterial cells (bactericidal activity) by use of impedance measurements (Maithus) . The detection times measured by the Malthus instrument were converted to cfu/ml (colony forming units per milliliter) by a calibration curve. Either direct or Indirect Malthus measurements were used when enumerating total survival cells (Malthus Flexi M2060, Malthus Instrument Limited). By the direct measurements, the cell metabolism was determined by conductance measurements in the growth substrate. The Malthus- method is based on the methods described in Johnston and Jones, (1995), Journal of Microbiological Methods 21, p. 15-26 and Johansen et al . (1995), Journal of Applied Bacteriology 78, p. 297-303. By the indirect measurements, 3 ml of growth medium was transferred to the outer chamber of the indirect Malthus cells, and 0.5 ml of sterile KOH (0.1 M) was transferred to the inner chamber. The cell suspensions were after enzyme treatment transferred to the outer chamber of the Malthus cell. As cells are growing in the outer chamber they produce C0 2 which will dissolve in the KOH in the inner chamber and thereby change the conductance of the KOH. The amount of C0 2 formed by the respiring cells surviving the enzyme treatment was used for estimating the number of viable cells. When the conductance change is measurable by the Malthus, a detection time (dt) will be recorded. The dt"s were converted to colony counts by use of a calibration curve relating cfu/ml to dt . The strains were grown in Brain Heart Infusion (BHI) (Oxoid CM 225) until stationary growth phase (30°C, 20 hours) , diluted in peptone water and inoculated to chemo-thermo- echanical-pulp CTMP at the final cell concentration of approximately 10 4 cfu/O.Olg CTMP. The CTMP was inoculated with either mono- cultures or a mixed culture of the three strains. The anti -microbial activity of the haloperoxidase (was determined at 35°C for 30 minutes, by adding the haloperoxidase to the bacterial cells adhering to the CTMP, together with hydrogen peroxide (0.5 mM) and artificial urine. The number of living cells was determined by transfer of the CTMP to Malthus cells . The activity of the haloperoxidase (0-2 mg enzyme protein/1 urine) was evaluated in artificial urine without electron- donor, thus the enzyme activity was initiated by the CI " in the urine. The haloperoxidase caused a total kill of the three test organisms; E. faecalis, E. coli and P. mirabili s . Furthermore the anti -microbial activity of the haloperoxidase was unchanged in artificial urine compared to a buffer system (pH 6) . A total kill of the mixed culture was found at haloperoxidase concentrations above 1.5 mg/1 and a hydrogen peroxide concentration above 0.75 mM. Figure 1, in which Z= bactericidal activity in log cfu/ml; X = mg/1 Curvularia verruculosa haloperoxidase; Y = mM H 2 0 2 , shows a response surface plot for the antibacterial activity in artificial urine of a haloperoxidase (rHP) against a mixed culture of E. faecalis, E. coli and P. mirabilis adhering to CTMP.

Claims: PATENT CLAIMS 1. An animal litter composition comprising an oxidoreductase 2. The composition of claim 1, wherein the oxidoreductase is selected from the group consisting of peroxidase, EC 1.11.1.-, and laccase, EC 1.10.3.2. 3. The composition of claim 2, wherein the peroxidase is a haloperoxidase, preferably selected from chloroperoxidase, bromoperoxidase and iodoperoxidase . 4. The composition of claim 3, wherein the haloperoxidase is a haloperoxidase obtainable from a strain of Curvularia . 5. The composition of claim 3, wherein the haloperoxidase is a vanadium haloperoxidase . 6. The composition of claim 2, wherein the oxidoreductase is a laccase. 7. The composition of claim 6, wherein the laccase is obtainable from a strain selected from Myceliophthora and Polyporus . 8. The composition of any preceding claim further comprising an oxidizing agent. 9. The composition of claim 8, wherein the oxidising agent is selected from the group consisting of hydrogen peroxide, precursors of hydrogen peroxide and oxygen. 10. The composition of any preceding claim, further comprising an enhancing agent . 11. The composition of claim 10, wherein the enhancer is selected from: (a) compounds having the formula: wherein the letter A in said formula denotes be a group such as -D, -CH=CH-D, -CH=CH-CH=CH-D, -CH=N-D, -N=N-D, or -N=CH-D, in which D is selected from the group consisting of -CO-E, -S0 2 -E, -N-XY, and -N + -XYZ, in which E may be -H, -OH, -R, or -OR, and X and Y and Z may be identical or different and selected from - H and -R; R being a C 1 -C 16 alkyl, preferably a C 1 -C 3 alkyl, which alkyl may be saturated or unsaturated, branched or unbranched and optionally substituted with a carboxy, sulpho or amino group; and B and C may be the same or different and selected from C m H 2m+1 , where m = l, 2, 3, 4 or 5, (b) compounds having the formula: wherein A is and B is the same as A, or B is H, or C1-C16 branched or unbranched alkyl wherein said alkyl may contain hydroxy, ether or ester groups, and R2 , R3 , R4 , R5 and R6 are H, OH, NH2 , COOH, S03H, C1-C12 branched or unbranched alkyl, acyl, N02 , CN, CI, CF3, NOH-CO-phenyl, C1-C6-CO-NOH-A, CO-NOH-A, COR12, phenyl -CO-NOH-A, OR7, NR8R9, COOR10, or NOH-CO-R11, wherein R7, R8, R9, RIO and Rll are C1-C12 branched or unbranched alkyl or acyl, (c) compounds having the formula: wherein R 1 , R 2 , R 3 , R 4 are individually selected from the group consisting of hydrogen, halogen, hydroxy, formyl , carboxy and salts and esters thereof, amino, nitro, alkoxy, carbonyl (C 1 -C 12 alkyl), aryl, in particular phenyl, sulpho, aminosulfonyl , carbamoyl, phosphono, phosphonooxy, and salts and esters thereof, wherein the R 1 , R 2 , R 3 , R 4 may be substituted with R 5 , wherein R 5 represents hydrogen, halogen, hydroxy, formyl , carboxy and salts and esters thereof, amino, nitro, C 1 -C 12 alkyl, alkoxy, carbonyl (C 1 -C 12 alkyl), aryl, in particular phenyl, sulpho, aminosulfonyl , carbamoyl, phosphono, phosphonooxy, and salts and esters thereof, [X] represents a group selected from (-N=N-), (-N=CR 6 -) m , (-CR 6 =N- ) m , (-CR 6 =CR 7 -) m , (-CR S =N-NR 7 -) , ( -N=N-CHR 6 - ) , ( -N=CR 6 -NR 7 - ) , (- N=CR 6 -CHR 7 -) , (-CR 6 =N-CHR 7 -) , ( -CR S =CR 7 -NR 8 - ) , and ( -CR 6 =CR 7 -CHR 8 - ) , wherein R 6 , R 7 , and R 8 independently of each other are selected from H, OH, NH 2 , COOH, S0 3 H, C^-alkyl, N0 2 , CN, CI , Br, F, CH 2 0CH 3 , OCH 3 , C00CH 3 ; and m is 1 or 2, (d) compounds having the formula: wherein R 1 , R 2 , R 3 , R 4 are individually selected from the group consisting of hydrogen, halogen, hydroxy, formyl , carboxy and salts and esters thereof, amino, nitro, C 1 -C 12 alkyl, alkoxy, carbonyl (C^C^ alkyl), aryl, in particular phenyl, sulpho, aminosulfonyl , carbamoyl, phosphono, phosphonooxy, and salts and esters thereof, wherein the R 1 , R 2 , R 3 , R 4 may be substituted with R s , wherein R 5 represents hydrogen, halogen, hydroxy, formyl , carboxy and salts and esters thereof, amino, nitro, C 1 -C 12 alkyl, C j -Cg alkoxy, carbonyl (C 1 -C 12 alkyl), aryl, in particular phenyl, sulpho, aminosulfonyl , carbamoyl, phosphono, phosphonooxy, and salts and esters thereof, (e) inorganic halide ions such as chloride, bromide and/or iodide and (f) compounds having the formula: R1 HN R2 wherein the substituent groups Rl and R2 is any of the following groups: hydrogen, halide, sulphate, phenyl, a straight or branched chain alkyl having from 1 to 14 carbon atoms, or a substituted straight or branched alkyl group having from 1 to 14 carbon atoms where the substituent group is located at C 1 -C 14 and represent any of the following radicals: hydroxy, halogen, formyl , carboxy, carboxy esters, carboxy salts, carbamoyl, sulfo, sulfo esters, sulfo salts, sulfamoyl, nitro, amino, phenyl, C 1 -C 5 -alkoxy, carbonyl -Ci-Cg-alkyl , aryl-C 1 -C 5 -alkyl . 12. The composition according to any preceding claim, further comprising a hydrolase enzyme. 13. The composition according to claim 12, wherein the hydrolase is selected from the group consisting of cellulase, hemicellulase, pectinase, amylase, protease, urease and lipase. 14. A process for reduction of malodour in soiled animal litters comprising contacting the soiled animal litter with an effective amount of oxidoreductase 15. Use of oxidoreductases for reduction of malodour in animal litters 16. A process for preparing an improved animal litter comprising the step of adding an oxidoreductase to the animal litter composition.

Inventors: JOHANSEN CHARLOTTE, JOHANSEN, CHARLOTTE
Applicants: NOVOZYMES AS, NOVOZYMES A/S
Application year: 2000
Main classification: A01K1
IPC codes: A01K1