Stabilized antibiotic compositions for animal feeding

Abstract: Stabilized antibiotic composition for animal feeds which provide for improved recovery of the antibiotic from the animal feed. The compositions contain the antibiotic in a coated form. In a preferred embodiment the antibiotic is coated by microencapsulation before being added to the animal feed.

Description: This invention relates to antibiotic animal feeds which provide for an improved recovery of the antibiotic from the feed upon analysis. More particularly, the recovery of virginiamycin from the animal feeds which contain ingredients which bind or interferes with the analysis of virginiamycin. Background The problem involved in the low recovery of antibiotics from animal feeds is a complex one and has long been recognized as a major problem facing the manufacturers and users of animal feeds. For example, the manufacturers may face problems with regulatory authorities because the initial assays do no comply with specifications or allowable limits. In some countries this may result in fines for the manufacturer. A low antibiotic initial assay also leads to customer dissatisfaction. EPA 165577 discloses a feed additive in which the antibiotic zinc bacitricin is coated in order to improve stability against the effects of heat, atmospheric moisture and mechanical processing. The low recovery of antibiotics such as virginiamycin from animal feeds is enhanced by the fact that modern day feeds, which are more aggressive, contain significantly higher levels of moisture, fat, ethoxyquin, meat and bone meal, fish meal, coccidiostats and trace minerals than do the normal feeds. By aggressive feeds is meant those feeds which contain higher levels of ingredients which have a detrimental or complexing effect on antibiotics than do normal feeds. For example, normal poultry feeds contain up to 4 percent fat. Aggressive poultry feeds contain above 5 percent fat. Normal cattle feeds contain about 8 to 10% moisture whereas aggressive cattle feeds contain 15-30% moisture. High moisture grains have become economically competitive. Further, modern day feeds provide for a cheaper form of proteins by the addition of meat and bone meal and fish meal. The addition of a higher percentage of fat to poultry feeds results in high energy levels. These levels are required by today's poultry due to their faster growth rate. Many attempts have been made to increase the virginiamycin recovery from the above noted aggressive animal feeds. One such attempt was granulating the antibiotic before adding it to the basic animal feed. This method is set forth in U.S. Patent 3,627,885. The animal feed having granulated virginiamycin present is known as Stafac™. The granulated virginiamycin did improve recovery from normal feed compositions over plain virginiamycin. However analysis of the aggressive feeds containing granulated virginiamycin resulted in low recovery and fell outside of allowable limits. Therefore the invention provides an animal feed composition comprising virginiamycin which provides for improved recovery of the virginiamycin from said feed composition characterised in that feed composition is an aggressive composition comprising a poultry feed containing above 5% fat or a cattle feed containing 15-30% moisture and the virginiamycin is coated by micrencapsulation. It is a further object of this invention to improve the recovery of virginiamycin from animal feeds which contain high levels of fat, moisture, and other deleterious ingredients noted above which effect the recovery of the virginiamycin. In a further aspect the invention provides a method of improving the recovery of virginiamycin from animal feed compositions as defined in claim 1 characterised in that the virginiamycin is coated by microencapsulation and subsequently added to the animal feed. Any method of microencapsulation well known to the pharmaceutical art may be employed. For example, fluid bed coating or spray congealing may be employed to microencapsulate the compound. Advantageously, the NCR process which is a chemical process based on coacervation techniques is the coating procedure employed. The coating material employed in the microencapsulation of the antibiotics of this invention may be fatty acid, alcohol or ester, alone or an admixture thereof. More specifically, the fatty acid may have from 10 to 22 carbon atoms and may be, for example, decenoic, stearic, palmitic, lauric or myristic acid. The fatty alcohols may have from 14 to 31 carbon atoms and may be, for example, lauryl alcohol, cetyl, stearyl, myristyl, carnubyl or ceryl alcohol. The esters may be mono-, di-, or trigylceryl esters. The coating material may be modified my waxy materials of natural or synthetic sources. Exemplary of such waxes are beeswax, spermacetic wax or carnauba wax. Additional coating materials that may be employed are for example, cellulose derivatives such as celluose acetate phthalate, ethyl cellulose, cellulose acetate butyrate and Eudragit compounds such as copolymers of dimethylaminoethylmethacylate and neutral methacylic ester. Preferably, the coating materials used in the microencapsulation process are gelatin, carboxymethylcellulose, cellulose acetate phthalate, starch, polyvinyl alcohol, and waxes. The present invention is particularly well adapted for recovering antibiotics, such as, for example, virginiamycin, tetracyclines, streptomycin, penicillins, erythromycin, oleandomycin, bacitracin, streptogramin, synergistin, pristinamycin, mikamycin and ardicin. In a preferred embodiment of this invention the antibiotic is virginiamycin and the coating material a mixture of gelatin and carboxymethylcellulose. The microencapsulated (coated) virginiamycin of this invention was tested and compared with granulated virginiamycin. The coating material present in the microencapsulated form was gelatin and carboxymethylcellulose. Virginiamycin was granulated according to U.S. Patent 3,627,885. Both the microencapsulated and granulated forms of virginiamycin were added to separate portions of the same basic cattle feed containing a high moisture content and the feed analyzed for virginiamycin recovery. The analysis used was the conventional microbiological paper disk diffusion method on agar-agar using corynebeacterium xerosis NCTC 9755 for determining the recovery of the antibiotic. The following example sets forth the procedure and results. Example Basic Cattle Feed Ingredients Percent W/W Corn Silage 30.00 Cracked Corn 60.00 Liquid Molasses 5.00 Cattle Pelleted Supplement 5.00 All the ingredients were thoroughly blended for 15 minutes and the moisture checked. The moisture content was 25%. To separate 4.5 Kg (10 pound) samples of the above basic feed an equivalent amount of virginiamycin in a granulated (Stafac™) and microencapsulated (coated) form was added. Each sample was stored in a sealed plastic bag and analyzed for percent virginiamycin recovery during a 14 day storage period at ambient temperature. The following results were obtained. Stafac™ (granulated) Microencapulate (coated) Inital Assay 111.7% 100.0% Day 7 80.0% 108.2% Day 14 60.0% 117.6% The results of this study clearly indicate that the microencapsulated or coated virginiamycin demonstrate significantly improved recoveries from a high moisture basic cattle feed than the granulated virginiamycin. A further study was conducted to compare granulated and microencapsulated virginiamycin in a pelleted poultry feed diet containing high fat (10%) and fish meal. Example Basic Poultry Feed Formula Ingredients % W/W Ground Yellow Corn 52.00 Soybean Meal (44%) 24.00 Fish Meal 3.00 Dehydrated Alfalfa Meal (17%) 5.00 Distillers Dried Grains with Solubles 2.00 Dicalcium phosphate 1.50 Ground limestone 1.50 Plain Salt 0.50 DL-Methionine 0.05 Vitamin/Mineral Premix 0.45 Animal Fat 10.00 The ingredients were thouroughly mixed and pelleted. To separate 4.5 Kg (10 pound) samples of the above basic feed an equivalent amount of virginiamycin in a granulated (Stafac) and microencapulated (coated) form was added. Each sample was stored in 3 ply Kraft paper bags and analyzed for percent virginiamycin recovery during a 60 day storage period at ambient temperatures. The following results were obtained. Stafac™ (granulated) Microencapulate (coated) Initial Assay 93.5% 103.4% Day 7 94.6% 103.5% Day 14 69.3% 89.9% The results of this study clearly demonstrates the much improved recovery of microencapsulated virginiamycin over the granulated form (Stafac™) from pelleted poultry feed containing high fat and fish meal.

Claims: Claims for the following Contracting States : DE, GB, FR, IT, NL, SE, LI, CH, BE, AT, LU, DK An animal feed composition comprising virginiamycin which provides for improved recovery of the virginiamycin from said feed composition characterised in that the feed composition is an aggressive composition comprising a poultry feed containing above 5% fat or a cattle feed containing 15-30% moisture and the virginiamycin is coated by microencapsulation. A feed composition according to claim 1 characterised in that the coating is a combination of gelatin and carboxymethylcellulose. A method of improving the recovery of virginiamycin from animal feed compositions as defined in claim 1 characterised in that the virginiamycin is coated by microencapsulation and subsequently added to the animal feed. The method according to claim 3 characterised in that the coating is a combination of gelatin and carboxymethylcellulose. Claims for the following Contracting States : ES, GR A process for preparing an aggressive antibiotic animal feed composition which comprises bringing into association virginiamycin and an animal feed characterised in that the animal feed is an aggressive composition comprising a poultry feed containing above 5% fat or a cattle feed containing 15-30% moisture and the virginiamycin is coated by microencapsulation. A process according to claim 1 characterised in that the coating is a combination of gelatin and carboxymethylcellulose. A method of improving the recovery of virginiamycin from animal feed compositions as defined in claim 1 characterised in that the virginiamycin is coated by microencapsulation and subsequently added to the aggressive animal feed. The method according to claim 3 characterised in that the coating is a combination of gelatin and carboxymethylcellulose.

Inventors: UNANGST RICHARD R, UNANGST, RICHARD R.
Applicants: PFIZER, PFIZER INC.
Application year: 1990
Main classification: A23K1
IPC codes: A23K1, A61K9