Effects of feeding selenium-yeast and chromium-yeast to finishing lambs on growth, carcass characteristics, and blood hormones and metabolites

Fifty-four male Rambouillet lambs (27 ± 4.8 kg body weight) fed a finishing diet and a daily supplement of selenium-yeast (0 or 0.3 mg Se-yeast) and chromium-yeast (0, 0.25, or 0.35 mg Cr-yeast) were used in a complete randomized design with a factorial (2×3) arrangement of treatments. Growth, feed intake, carcass characteristics, plasma triglycerides, cholesterol, glucose, urea-N, insulin, cortisol, thyroxine (T4), and triiodothyronine (T3), and serum immunoglobulin G (IgG) concentrations were measured. Daily weight gain, total weight gain, feed intake, and feed conversion were not affected by Se-yeast supplementation. There was a linear decrease in feed intake, but a linear increase of the 12th rib area, retained protein, and plasma glucose as the Cr-yeast supplementation increased in lambs without Se-yeast supplement. There were quadratic effects of Cr-yeast on plasma triglycerides and insulin concentrations, carcass fat and protein, retained fat and energy, and fat free carcass in lambs without Se-yeast. Final BW, total gain, and average daily gain were linearly increased as Cr-yeast increased in Se-yeast supplemented lambs. Cr-yeast affected all carcass variables in Se-yeast supplemented lambs. Quadratic effects of Cr-yeast were observed on slaughter BW, hot and cold carcass, 12th rib area, and retained energy in lambs fed Se-yeast. Fat (g/kg BW) and retained fat (kg) in carcass showed a linear reduction as Cr-yeast increased in lambs fed Se-yeast. Thus, carcass and retained protein, as well as fat free carcass decreased linearly as Cr-yeast supplementation increased. These results suggest that Se-yeast and Cr-yeast interact to enhance growth, modify carcass characteristics and affect blood hormones and metabolites of lambs.