Effect of Source and Level of Supplemental Bypass Total Sulfur Amino Acids (TSAA) on Performance of Growing Cattle Fed Bermudagrass Hay Diets Supplemented with Molasses Based Supplements

Total sulfur amino acids (TSAA) in undegradable intake protein (UIP), were fed with molasses in an evaluation of steer and heifer performance during the winter of 1999/2000. Eight treatments were offered and consisted of control (molasses only), corn gluten meal (CGM) fed at 3 g UIP, CGM fed at 6 g UIP, Mepron M 85 (MEP) (bypass synthetic methionine) fed at 3 g UIP, MEP fed at 6 g UIP, Smartamine M (SMT) (bypass synthetic methionine) fed at 3 g UIP, SMT fed at 6 g UIP, and Alimet (ALI) (bypass synthetic methionine) fed at 3 g UIP. Cattle were randomly assigned to 32 pastures (2 acres) with two heifers and two steers in each pasture for the 112-d trial. Calves averaged 281 kg with a body condition score (BCS) of 5.56 at the start of the trial. Bermuda grass hay was offered ad libitum and molasses slurries were limit fed at 6 lb/d twice a week in open troughs. Effects on daily gain, BCS, and hip height were monitored. Supplementation of bypass TSAA increased cattle gains by 0.11 lb/d over control (1.12 vs 1.25 lb/d). Cattle supplemented with 3 or 6 g/d of bypass TSAA had similar gains (1.26 vs 1.26 lb/d). Cattle supplemented with 6 g/d bypass TSAA from CGM grew more in hip height (2.91 in) than those fed 3 g/d bypass TSAA from MEP (2.08 in) or control (1.88 in). Supplemental sources and levels of bypass TSAA did not significantly affect body condition scores. Level of TSAA fed was not a good predictor of animal performance.