Effect of Salinomycin on Feed Efficiency, Ruminal and Blood Characteristics of Steers

Abstract

Salinomycin (SL) is a polyether antibiotic produced by Streptomyces albus. Five steers per pen were fed a concentrate supplemented with 0 and 30ppm SL for 40 weeks starting from 7 months of age. A 40-week feeding SL period was followed by a 9-week period during which SL was omitted from the concentrate diet. Neither final body weights nor average daily gains were affected by feeding SL, but feed efficiency was improved by 12% due to the decrease of feed intake (Table 2). Ruminal fluid was collected at 4, 20, and 40 weeks after starting feeding SL.Total ruminal volatile fatty acid concentration was not affected by feeding SL, but the molar proportion of propionic acid increased and that of acetic acid or butyric acid decreased. Consequently, the acetate to propionate ratio decreased with SL (Table 3). Ruminal fluid ammonia concentration appeared to be lower for steers fed SL than for control animals (Table 3). Ruminal fluid pH was not consistently affected with SL (Table 3). Blood samples were taken at 0, 8, 20, 32 and 40 weeks after starting the experiment. Serum proteins, calcium, phosphate, magnesium, cholesterol and urea nitrogen levels were within normal ranges and were not affected by feeding SL (Table 4).