PSXII-32 Effects flavomycin, narasin and salinomycin on ruminal fermentation of Nellore steers fed high forage diet

Abstract

Abstract The aim of this study was to evaluate three feed additives for rumen manipulation. Thirty-two rumen-fistulated animals were assigned to a completed randomized block design, according to their initial BW. Steers were fed with 99% of coastcross haylage and 1% of concentrate, used as vehicle for the additives. The forage and concentrate were offered separately, whereas the forage was offered after the entire consumption of the concentrate. The experimental diets consisted in: CON = Control (no feed additive); NAR = 13ppm of Narasin; SAL = 20ppm of Salinomycin; and FLA = 3ppm of Flavomycin. The experimental period lasted 140 d, divided on 5 periods of 28 d each. Rumen fluid was collected on d 0, 28, 56, 84, 112 and 140, at 0, 6 and 12 hours after feeding and combined as a pool for SCFA analysis. Data were analyzed using the MIXED procedure of SAS. Data obtained on d 0 were used as covariate. Tukey test 5% was used for comparisons. There was treatment effect on acetate (CON: 73.5ab; NAR: 73.0a; SAL: 73.9b and FLA: 73.6b mM/100mM, P = 0.01; SEM = 0.16), propionate (CON: 13.7b; NAR: 14.6a; SAL: 13.5b and FLA: 13.4b, P = 0.01; SEM = 0.11), butyrate (CON: 9.06a; NAR: 8.64b; SAL: 8.72ab and FLA: 8.96ab, P = 0.02; SEM = 0.10), isovalerate (CON: 1.51b; NAR: 1.61ab; SAL: 1.55ab and FLA: 1.67b, P = 0.03; SEM = 0.04) and ac:prop ratio (CON: 5.39a; NAR: 4.99b; SAL: 5.49a and FLA: 5.4a, P = 0.01; SEM = 0.05). Therefore, narasin improves energetic efficiency of ruminal fermentation compared to other additives.