Effects of no shade, shade and shade plus chromium supplementation on growth performance, blood metabolites, and carcass traits of Bos indicus-influenced finishing steers under heat stress

This study evaluated the effects of shade removal, shade provision, and shade plus chromium ( Cr ) propionate supplementation on growth performance, metabolic responses, thermotolerance, and carcass characteristics of Bos indicus -influenced finishing steers exposed to hot and humid conditions. Twenty-four steers [body weight (BW) = 464 ± 15 kg] were assigned to one of three treatments for an 80-d experimental period: (1) control (no shade, and no Cr supplementation, CON ), (2) shade and no Cr supplementation ( S ), or (3) shade + Cr supplementation (0.5 mg Cr/kg DM, SCr ). Treatment × day interactions ( P ≤ 0.05) were observed for BW, DMI, ADG, glucose, NEFA, and cortisol. The SCr steers had greater BW on d 28, 42, 70, and 80 and DMI from 0 to 42 compared to that of S steers. Serum glucose concentrations were lower ( P = 0.01) in SCr steers on d 56 and 70, and serum cortisol concentrations were reduced ( P < 0.01) on d 14 and tended ( P =0.10) to remain lower throughout the experimental period. Shade reduced ( P < 0.01) respiration rate and rectal temperature during peak afternoon heat load. Shade plus chromium supplementation increased ( P ≤ 0.05) hot carcass weight and backfat thickness, with no effects ( P ≥ 0.20) on dressing percentage, longissimus muscle area, or marbling score. These results indicate that shade improved thermotolerance, whereas steers receiving shade plus Cr supplementation exhibited improved growth performance and carcass traits under hot and humid conditions.