298 The Effects of Chromium Propionate Supplementation to Calf-fed Steers in a Commercial Feedyard on Growth Performance, Carcass Characteristics and Health

Abstract

Abstract Crossbred steers [British x Continental x Bos Indicus; n = 1844; initial body weight (BW) = 248 ± 28 kg] were used to evaluate the effects of chromium propionate supplementation to calf-fed steers in a commercial feedyard on growth performance, carcass characteristics and health. Steers were blocked by initial BW; pens were assigned randomly to one of two dietary treatments within block. Treatments, replicated in 15 pens/treatment with 57 to 62 head per pen, included: 1) control, 0 mg supplemental Cr/kg dietary dry matter (DM) (CTL); 2) 0.50 mg supplemental Cr/kg dietary DM (chromium propionate; KemTRACE® Chromium 0.04%, Kemin Industries, Des Moines, IA) (CR). Due to inadvertent oversight, during the final 30 days on feed, CR cattle did not receive trace minerals, vitamins, an ionophore, antibiotic, or ractopamine-hydrochloride. Final BW, average daily gain (ADG) and DM intake did not differ among treatments (P ≥ 0.25). Gain efficiency was greater (P = 0.03) for CTL than CR (0.16 vs. 0.15). Hot carcass weight and dressing percentage were similar among treatments (P ≥ 0.19). Yield grade was higher for CR than CTL (2.44 vs. 2.27; P < 0.01); 12th-ribfat tended to be greater for CR than CTL (P = 0.09), and longissimus area was greater for CTL vs. CR (P < 0.01). Marbling score tended (P = 0.10) to be greater for CR than CTL. Steers fed CR tended (P = 0.07) to have a greater distribution of prime carcasses than CTL (1.9% vs. 0.07%), and percentage choice carcasses was higher for CR than CTL (67.34% vs. 61. 71%, P = 0.01). Respiratory morbidity (12.20%), and retreatment rate did not differ among treatments (P ≥ 0.20). In the absence of a beta-agonist, CR steers had higher quality carcasses, and similar ADG and HCW to CTL.