Effects of dietary sulfur addition and synovex s ear implants on feedlot steers fed an all concentrate finishing diet
Journal of Animal Science 46(2): 463-477
ISSN/ISBN: 0021-8812 DOI: 10.2527/jas1978.462463x
A series of 3 trials was conducted to study the effects of dietary S addition and Synovex-S ear implants on feedlot steers fed an all-concentrate finishing diet. In trial 1, 48 beef steers were implanted with diethylstilbestrol (DES) and fed for 28 wk an all-concentrate diet supplemented with either 0, 1.4, 4.2 or 9.8 g sublimed S/kg diet. The 9.8 g-S treatment was ended at 10 wk because of low feed intakes and weight loss. Rate of gain was not different among treatments with 0, 1.4 and 4.2 g of S, but feed:gain ratio was improved .apprx. 5.5% with both levels of S supplementation. In trial 2, 48 beef steers and 16 dairy steers were fed for 28 wk the same all-concentrate diet as in trial 1 supplemented with either 0 or 1.4 g of S/kg diet. The steers were stratified according to breed, and 1/2 of the steers in each breed-sulfur treatment group were implanted with Synovex-S implants. Among the implanted steers, S supplementation improved the feed:gain ratio by 10%. Growth rate was 25% greater and feed:gain ratio was 11% less for Synovex-S implanted steers. Neither S nor Synovex-S had consistent effects on carcass merit, ruminal pH, ammonia (NH3), volatile fatty acids (VFA) and lactic acid, or on blood plasma NH3, amino acids and lactic acid. In trial 3, 8 ruminal fistulated beef steers in a replicated experiment were fed the same all-concentrate diet as in trial 1 supplemented with either 0, 1.4 or 4.2 g of S/kg of diet. Steers were withheld from feed for 96 h (restricted) and then refed as a means of causing ruminal lactic acid accumulation. S supplementation appeared to lower the peak accumulation of both D- and L+ lactic acid after feeding. Concurrent ruminal NH3 and VFA data suggested a more optimal ruminal fermentation for the supplemental S treatments; part of the benefit from supplemental S may be to reduce intermittent lactic acid accumulation in the rumen.