Stabilization method

The method of stabilizing the antibiotic tylosin for use in an animal feed premix and in animal feeds, which method comprises the steps of:

• A. intimately blending a mixture comprising from about 1 to about 40 percent on a dry weight basis of the antibiotic, about 50 to about 98 percent on a dry weight basis of a finely ground diluent selected from the group consisting of solvent-extracted soybean feed and alfalfa meal, with water, or intimately blending a mixture comprising from about 1 to about 20 percent on a dry weight basis of the antibiotic, about 50 to about 98 percent on a dry weight basis of a finely ground diluent selected from the group consisting of soybean mill run, milo flour, wheat middlings, and corn flour, with water, to form an intimate admixture;
• B. blending the intimate admixture (A) with a physiologically-acceptable binder selected from the group consisting of hydrolyzed starch, gelatin, polyvinylpyrrolidone, soy protein, cellulose, bentonite, acacia powder, and lignin sulfonate, the binder amounting to from about 1 to about 10 percent of the weight of the components of step (A), to produce a wet but freeflowing particulate material;
• C. extruding the blend of (B) under pressure through round perforations of from about 0.3 mm. to about 1.0 mm. in diameter, forming an extrudate of elongated strands having a length generally exceeding the cross-sectional dimension;
• D. reducing the strands of extrudate (C) into particles of from about one to about five times their cross-sectional dimension in length;
• and
• E. drying the particles from (D) at a temperature ranging from about room temperature to about 70.degree. C. to a residual moisture content of from about 5 to about 12 percent.