Abstract:
The invention provides pre-mixture for animal feeding comprising: (a) a polymer or a mixture of polymers, with a content in mannose comprised between 10% and 100%; (b) β-mannanase enzyme; and (c) an anti-binding agent; wherein the anti-binding agent has an absorptive capacity higher than 20%, and a bulk density which is comprised between 0.10 and 2.70 g/cm 3 . The pre-mixture of the invention diffuses better through the intestinal tract and effectively inhibits the colonization of Gram negative bacteria without affecting the growth of the animal.

Description:
[0001]    The present invention relates to a pre-mixture for animal feeding which is effective in the reduction or prevention of pathogenic Gram negative bacteria in the animal intestinal tract. 
       BACKGROUND ART 
       [0002]    Poultry and meat are frequent sources of food borne disease organisms. The pathogens associated with poultry products include  Salmonella  spp.,  Listeria monocytogenes, Escherichia coli  and  Campylobacter jejuni . These microorganisms are introduced into poultry and animal flocks during raising and onto carcasses during processing. These bacteria colonize the mucus covering gut surfaces and can also be found in deep mucus of intestinal crypts. 
         [0003]    The infection of  Salmonella enteritidis  (SE) in poultry is one of the most serious problems in the poultry industry because of related outbreaks of food poisoning. Much effort has been made to inhibit  Salmonella  spp. infection in poultry. The inhibition of  Salmonella  spp. with antibiotics does not seem to be practical because of the occurrence of resistant bacterial strains and the residual toxicity of antibiotics in poultry products. 
         [0004]    Recently vaccination has become a common approach, but it has several limitations. Vaccine therapy cannot distinguish whether the origin of the antibody derives from the vaccine or from a bacterial pathogen when  Salmonella  serology is done. Thus, the period of vaccination must be strictly programmed and is restricted to a specific interval of time. It has been reported that some kinds of carbohydrates, yeast, and, especially, the mannose residue are effective in preventing the  Salmonella  spp. colonization. 
         [0005]    Other recent approach is based on the use of certain monomeric and dimeric sugars in the poultry diet to reduce the levels of  Salmonella  organisms that colonize their gut. As previously indicated, sugar receptors on the surfaces of intestinal epithelial cells apparently serve as receptors for the binding of some bacterial pathogens. The interaction between the Gram-negative bacterial pili and these receptors can be blocked by certain simple sugars in the animal feed. 
         [0006]    In the PCT application number WO03101219 it is described a pre-mixture for use in animal feeding. In this application a pre-mixture comprising locust bean gum, a liquid hydrolase preparation and sepiolite (which is an acceptable additive for animal feeding) is described. This mixture was used against  Salmonella&#39;s  colonization in chicks. 
         [0007]    Despite the efforts made in the prior art, the research of new compositions more effective in the prevention or inhibition of colonization of Gram negative bacteria (such as  Salmonella  spp.) is still an active field. 
       SUMMARY OF THE INVENTION 
       [0008]    Inventors have found that a pre-mixture of a polymer with a content in mannose comprised between 10% and 100%; a β-mannanase enzyme; and an anti-binding with an specific absorptive capacity and bulk density is effective against Gram negative bacteria colonization in the animal intestinal tract. Particularly, this pre-mixture has a high fluidity, implying a better diffusion through the intestinal tract. The main advantages of this high fluidity and diffusion is that the efficacy of the pre-mixture is increased and, therefore, a low inclusion dose (i.e., amount of the mixture into the feed animal) for achieving the desired effect (i.e., to avoid bacterial colonization) is needed. As it is shown below, a small amount of the mixture of the invention is enough to achieve the desired effect, which means that there is a small raise of the total of the fodder that must be administered. This is of great importance because when the farm animal has to be nourished, a fix amount of fodder is administered. If the mixture of the invention had to be supplied in a high amount, the amount of fodder should be reduced and, therefore, the diet of the animal would not be appropriate for its growth. In this case additional nutrients should be added to the fodder to help to the appropriate growth of the animal. 
         [0009]    From the teachings of WO03101219 it was known that a mixture comprising sepiolite as technological acceptable additive, together with a liquid hydrolase preparation, and a natural gum, has the ability of inhibiting  Salmonella&#39;s  colonization. In the examples of said application, the mixture amounts used are of 2.5% and 5% by weight over the total fodder weight, i.e., from 5 to 10-fold higher than the one used in the examples included below for inhibiting the bacteria colonization. 
         [0010]    Advantageously, as the mixture of the invention is effective at a low amount (for instance, in Tables 2 and 3 the amount is 0.5% by weight/total fodder), it is practically maintained the amount of fodder, maintaining the levels of nutrients needed to the appropriate growth of the animal and, therefore, being not needed the addition of other components. 
         [0011]    On the other hand, it is relevant that when the pre-mixture of the invention is administered, the conversion index is maintained when compared with a control. A value of the conversion index significantly equal to the control group is indicative of a good transformation (the food administered to the animal is transformed in meat/eggs). A different value significantly higher is indicative of an inappropriate transformation (a huge amount of food must be administered to the animal in order to achieve the desired amount of meat/eggs). As it is illustrated below (Table 1, line T-3), the pre-mixture described in WO03101219 has a conversion index significantly different from the conversion index of the control group. Advantageously, when the pre-mixture of the invention is administered (Table 2, lines T-2 and T-3) there no significant differences with the control group. 
         [0012]    Thus, in a first aspect the present invention refers to a pre-mixture for animal feeding comprising: (a) a polymer or a mixture of polymers, having a content in mannose comprised between 10% and 100%; (b) β-mannanase enzyme; and (c) an anti-binding agent; wherein the anti-binding agent has an absorptive capacity higher than 20%, and a bulk density which is comprised between 0.10 and 2.70 g/cm 3 . 
         [0013]    Surprisingly, the use of an anti-binding agent having such properties (i.e., the absorptive capacity and bulk density) instead of sepiolite, improves the efficacy in the inhibition of colonization. This improvement makes possible the use of the pre-mixture of the invention in an amount about at least 5 fold lower than the amount needed in WO03101219 to achieve the same effect (as it has been explained above). 
         [0014]    Without being bound to the theory, it is believed that using an anti-binding agent according to the first aspect of the invention, the enzyme diffuses better in the pre-mixture, being more effective when it has to hydrolyze its substrate (i.e., the polymer). 
         [0015]    The diffusion improvement also affects to the resulting product (the polymer hydrolyzed by the β-mannanase). Thus, the resulting product, owing to the presence of the anti-binding agent, diffuses better into the intestinal tract, being its efficacy in the inhibition of the bacterial colonization improved. 
         [0016]    In a second aspect, the present invention refers to an animal feed composition comprising the pre-mixture as defined according to the first aspect of the invention. 
         [0017]    In a third aspect, the present invention refers to the use of a pre-mixture according to the first aspect of the invention, for the preparation of an animal feed composition for the inhibition of Gram negative bacteria colonization in the animal intestinal tract. This aspect may be formulated as a method of treatment of an animal, suffering from or being susceptible of suffering from a Gram negative bacteria colonization by administering the pre-mixture of the present invention as defined above. 
         [0018]    It is also part of the invention a pre-mixture as defined above for use as inhibitor of Gram negative bacteria colonization in the animal intestinal tract. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    In the present invention, the expression “a polymer with a content in mannose comprised between 10% and 100%” encompasses homopolysaccharides consisting exclusively of mannose units (i.e., a polysaccharide with a content of 100% in mannose) and heteropolysaccharides comprising mannose and other sugar units such as glucose, galactose, α-galactose derivative, galactomannans, galactosamine, fucose, and arabinose, for instance. Polymers according to the present invention includes, but are not limited to: guar gum, xanthan gum, pectin, gum tragacanth, gum arabic,  cassia  gum, palm kernel meal, algin, carrageenan, locust bean gum, locust bean seed, and mixtures thereof. 
         [0020]    In one embodiment of the first aspect of the invention, the polymer has a content in mannose comprised between 10% and 60%. 
         [0021]    In the present invention, the term “anti-binding agent” encompasses any substance which reduces or avoids the adhesion between the compound particles resulting from the β-mannanase activity. 
         [0022]    In a preferred embodiment of the first aspect of the invention, the anti-binding agent has an absorptive capacity comprised between 60 and 70% and a bulk density comprised between 0.10 and 0.30 g/cm 3 . 
         [0023]    The absorptive capacity of the anti-binding agent is determined using the following protocol:
       1. Tare a 50 mL volumetric flask over the scale.   2. Add 50 g of the anti-binding agent to be determined.   3. With the graduated cylinder add gradually deionized water and stir with the glass bar until its total absorption by the anti-binding agent.   4. Repeat this operation (point 3) until the anti-binding agent will not be able to absorb more liquid.   5. The analysis must be performed by duplicate.   6. The following equation is applied:       
 
         [0000]      Absorption capacity=[g deionized water/(g deionized water+g anti-binding agent)]*100. 
         [0030]    The bulk density of the anti-binding agent is determined using the following protocol:
       1. Tare a 50 ml graduated cylinder over the semi-analytical balance (0.01 g accuracy).   2. Fill the graduated cylinder to the line with the anti-binding agent. Don&#39;t knock the graduated cylinder in order to avoid incorrect results.   3. Weigh the filled cylinder.   4. Make the determination twice.   5. Bulk density=weight (g)/50 ml=g/ml. (The final results is the mean of both determinations).       
 
         [0036]    When the pre-mixture of the invention is prepared, it is preferably obtained as a homogenous solid mixture. In order to obtain the homogeneous solid mixture, the enzyme can be in solid form, e.g., powder. 
         [0037]    The fact that the enzyme is in a solid form, makes easier its handling and improves its diffusion through the intestinal tract. In WO03101219 the sepiolite additive was used as vehicle in order to “solidify” the enzyme, which was initially in the form of liquid preparation. In the present invention, the use of an anti-binding agent with the properties pointed out above avoids the appearance of lumps in the pre-mixture, which would difficult the diffusion of the mixture into the intestinal tract and, hence worsening its effectiveness in the inhibition of the bacteria colonization. 
         [0038]    In still another preferred embodiment of the first aspect of the invention, the ratio of the enzyme is comprised between 5 and 40 enzymatic activity units per gram of polymer. The enzymatic activity units are determined for the b-mannanase enzyme as quantity of enzyme that releases 1 micromol of mannosa per minute from carob galactomannan at 40° C. and pH=4. 
         [0039]    In another embodiment of the first aspect of the invention, the polymer is selected from the group consisting of: guar gum, xanthan gum, pectin, gum tragacanth, gum arabic, algin, carrageenan, locust bean gum, locust bean seed,  cassia  gum, palm kernel meal, and mixtures thereof. 
         [0040]    In the present invention the “β-mannanase enzyme” comprised in the pre-mixture of the invention can be of natural or synthetic origin. By “synthetic origin” it is encompassed any form of the enzyme obtained by engineering techniques (e.g., recombination). 
         [0041]    In a preferred embodiment of the first aspect of the invention the β-mannanase enzyme is E.C. 3.2.1.78 according to the nomenclature of the International Union of Biochemistry. 
         [0042]    In another preferred embodiment of the first aspect of the invention, the amount of anti-binding agent is comprised between 0.5 and 4% by weight with the respect the total weight of the pre-mixture. 
         [0043]    Illustrative non-limitative examples of anti-binding agents are: precipitated and dried acid silicic (E551a), colloidal silica (E551b), vermiculite (E561), Kieselgur (E551c), synthetic calcium silicate (E552), synthetic sodium and aluminium silicate (E554), synthetic calcium aluminates (E598), clinoptilolite from volcanic origin (E567). The “E” number, for instance “E551a”, corresponds to the additive number authorized in the European Union. In a preferred embodiment of the first aspect of the invention, the anti-binding agent is selected from the group consisting of: precipitated and dried acid silicic (E551a), colloidal silica (E551b), and vermiculite (E561). 
         [0044]    In a preferred embodiment of the second aspect of the invention, the pre-mixture is comprised between 0.05 and 1.5% by weight of the total composition. 
         [0045]    As it has been mentioned throughout the description, the pre-mixture of the present invention is useful in the effective inhibition of the colonization of Gram negative bacteria. The term “Gram negative bacteria” includes, but it is not limited to, bacteria exhibiting fimbria, such as Enterobacteriaceae, among others. In a preferred embodiment of the third aspect of the invention, the Gram negative bacteria is  Salmonella.    
         [0046]    Throughout the description and claims the word “comprise” and variations of the word, such as “comprising”, is not intended to exclude other technical features, additives, components, or steps. 
         [0047]    The following examples are provided by way of illustration, and is not intended to be limiting of the present invention. 
       EXAMPLES 
     Example 1 
     Preparation of a Pre-Mixture According to the Present Invention in a Proportion of 0.5% in Weight in Relation to the Diet for the Animal 
       [0048]    Per ton of feed the premix is prepared as follows:
       (i) Locust bean gum: 4.482, 5 g   (ii) Beta-mananase: 21.5 g   (iii) Locust bean seed: 446 g   (iv) Silicic acid: 50 g       
 
         [0053]    To obtain the premix of this finding: (1) components (iv) and (iii) have to be mixed on a first stage. On a second phase: (2) ⅓ of (i) has to be mixed with the totality of (ii). After the homogeneous mix, add the rest of (i) to this last premix. Finally, mix homogeneously (1) and (2). 
       Example 2 
     Trial with Leghorn Chickens Consuming Feed Supplemented with Different Products of the State of the Art for 28 Days 
       [0054]    Chickens were allocated in cages, at the rate of 5 animals/cage, in the experimental farm of the Animal Nutrition Department of IRTA. Diet was based on corn-soyabean in mash form. Application of the premix was always by substitution of corn. 
         [0055]    Chickens were challenged with  Salmonella enteritidis  marked with nalidixic acid. Efficacy of the application of each one of the products was assessed by means of a determination of  Salmonella  presence in chickens&#39; caecum. Chicken&#39;s were challenged at one day old, when they arrived to the experimental farm, by inoculating  Salmonella enteritidis  (S-2146/c/03 Tn 5 12 ), strains resisting 20 μg/ml nalidixic acid and 12 μg/ml CIHg. Strains were originated from the L.S.A. collection, Barcelona. 
         [0056]    During the 28 days of the experiment data from feed consumption and initial and final body weights were collected. With those data the following parameters were calculated: Daily Body Weight Gain (DBWG) (g/d), Daily Feed Intake (DFI) (g/d) and Feed Conversion Index (FCI) (Daily Feed Intake/Daily Body Weight Gain). a, b, c: different letters in the same column mean significant differences. 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Treatment 
                 Added product 
                 DBWG 1   
                 DFI 2   
                 FCI 3   
                 Infection/15 days 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 T-1 
                 Control (no added product) 
                 8.9 (a) 
                 18.2 (a) 
                 2.04 (c) 
                 12/12 
                 100% 
               
               
                 T-2 
                 Locust bean gum 2.5% 
                 6.8 (b) 
                 17.2 (a) 
                 2.52 (a) 
                 6/12 
                 50% 
               
               
                 T-3 
                 Locust bean gum 
                 6.9 (b) 
                 17.0 (a) 
                  2.46 (ba) 
                 4/12 
                 25% 
               
               
                   
                 5% + sepiolite + 
               
               
                   
                 β-mananase (WO03101219) 
               
               
                   
               
             
          
         
       
     
         [0057]    Using the pre-mixture described in WO030101219, a reduction in the infection is achieved. However, the index of conversion is significantly higher compared with the control and it is observed a decrease in the body weight gain. 
       Example 3 
     Experimental Results Using the Pre-Mixture of the Invention 
       [0058]    Hens were allocated in cages, at the rate of 5 animals/cage, in the experimental farm of the Animal Nutrition Department of IRTA. Diet was based on corn-soyabean in mash form. Application of the premix prepared as explained in Example 1 was always by substitution of corn. 
         [0059]    Each 4 weeks data from feed consumption and changes in body weight were recorded. With those data the Feed Conversion Index (Daily Feed Intake/Daily Body Weight Gain) was calculated. Results are shown in Table 2. 
         [0060]    On day 27 of treatment, all hens were orally challenged with  Salmonella enteritidis . The strains used were a mixture of GN825 and GN1063, which had been selected from the most invasive in previous trials. In two of the treatments, control and New product at 0.5%, every fourth week (at the end of each 4 week period), 8 animals per treatment were euthanized and ovarios and caecum examined for  Salmonella  presence/absence.  Salmonella enteritidis  study was conducted in accordance with the modified ISO standard. Briefly: tissue samples were collected in sterile plastic containers with 225 ml of buffered peptone water; incubation; addition of 3 drops of the pre-enrichment broth in a semi-solid media Rappaport-Vassiliadis and incubation of this media. Putative  Salmonella  white colonies were transferred on XLT4 agar plates to confirm the presence/absence of  Salmonella . Results are shown in Table 3. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                 Body Weight 
                   
                   
               
               
                 Treatment 
                 Added product 
                 Change (g) 
                 DFI 1  (g) 
                 FCI 2   
               
               
                   
               
             
             
               
                 T-1 
                 Control (no added 
                 48 
                 106 
                 2.33 
               
               
                   
                 product) 
               
               
                 T-2 
                 New product 0.5% 
                 45 
                 104 
                 2.39 
               
               
                 T-3 
                 New product 5% 
                 44 
                 103 
                 2.41 
               
               
                   
               
             
          
         
       
     
         [0061]    From the results obtained with the pre-mixture according to the present invention, the conversion index is substantially maintained compared with the control group and the body weight change when the pre-mixture is administered to the infected animals is practically maintained when compared with the control group. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Results of microbiological analysis from caecum and ovary at different time 
               
               
                 periods after inoculation (% of birds with presence of  Salmonella ). 
               
             
          
           
               
                   
                 Added 
                 Before 
                 Infection/ 
                 Infection/ 
                 Infection/ 
                 Infection/ 
               
               
                 Treatment 
                 product 
                 inoculation 
                 30 days 
                 90 days 
                 120 days 
                 150 days 
               
               
                   
               
             
          
           
               
                 T-1 
                 Control (no product added) 
                 0.0 
                 25.0 a   
                 25.0 a   
                 12.5 a   
                 12.5 a   
               
               
                 T-2 
                 Product of the invention 0.5% 
                 0.0 
                 6.3 b   
                 6.3 b   
                 0.0 b   
                 0.0b