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

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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