EFFECT OF SALINOMYCIN ON NUTRIENT ABSORPTION AND RETENTION BY GROWING PIGS FED CORN-SOYBEAN MEAL DIETS WITH OR WITHOUT OAT HULLS OR WHEAT BRAN

Abstract

Four balance trials were conducted to determine the effect of the antibiotic salinomycin (SM) on nitrogen (N) and energy utilization and fiber component digestibility by swine fed low- or high-fiber diets. Treatments were corn-soybean meal control (C), 10% oat hull (OH) and 20% wheat bran (WB) diets, each with or without SM (82 mg kg−1). In trial 1A, 12 female pigs (34.6 kg) were fed the C or WB diets with or without SM for a 9-d adaptation period followed by a 5-d feces and urine collection period. In trial IB, the same pigs (50.5 kg) were fed the C or OH diets with previous fiber and SM levels reversed. Trial 2 was conducted in a similar fashion with the order of the fiber sources fed reversed (OH in trial 2A, 32.3 kg; WB in trial 2B, 44.7 kg). SM increased apparent N digestibility and N absorption (P < 0.01) in the WB trials, but also increased (P < 0.05) urine N and thus SM did not affect N retention. Although apparent N absorption was decreased (P < 0.06) by SM in the OH trials, this largely reflected a lower N intake (P < 0.02) and SM did not alter N retention. SM did not alter apparent energy utilization by pigs fed the C or OH diets, but increased the coefficients for DE and ME (P < 0.01) and dry matter (DM) digestibility (P < 0.05) of pigs fed the WB diets. Both OH and WB decreased apparent N digestibility (P < 0.01), but did not affect N retention (P > 0.10). OH and WB decreased (P < 0.01) energy digestibility. Digestion coefficients for DM, acid detergent fiber, neutral detergent fiber, cellulose and hemi-cellulose were not affected by SM, but were depressed by OH and WB (P < 0.01). Estimated DM digestibilities (calculated by difference) for OH and WB were 4.9% and 61.3%, respectively. The data indicate that SM may influence energy and N utilization in pigs fed a degradable source of fiber (WB), but not in pigs fed a low-fiber diet (C) or a diet containing a high-fiber ingredient resistant to fermentation (OH). This suggests that SM may alter microbial fermentation in the gastrointestinal tract of the pig. Key words: Swine, fiber, salinomycin, nitrogen utilization, energy utilization