Tylosin phosphate (TP) and tylosin urea adduct (TUA) for the prevention of liver abscesses, improved weight gains and feed efficiency in feedlot cattle.

Four feedlot experiments with 774 cattle have been completed during 1969 to 1970 evaluating two forms of tylosin activity (50, 75 and 100 mg per head per day continuously of tylosin phosphate or tylosin urea adduct) in high concentrate rations. Continuous administration of these three levels of antibiotic activity from either form of tylosin (1) reduced the incidence of liver abscesses, (2) increased average daily gain, and (3) improved feed conversion of feedlot cattle. Mathematically combining data from all levels of both forms of tylosin demonstrated an 81.8% reduction (24.1% control vs. 4.2% treated)in incidence of liver abscesses (P < .01), a 5.9% increase (2.23 lb. [1.01 kg] control vs. 2.36 lb. [1.07 kg] treated) in average daily gain (P < .05) and a 3.1% improvement (7.65 control vs. 7.41 treated) in feed conversion (P < .10). Control cattle with normal livers gained 17.0 lb. (7.7 kg) more weight during the feeding period than control cattle with abscessed livers.