CARCASS CHARACTERISTICS AND TISSUE-MINERAL CONTENTS OF STEERS FED SUPPLEMENTAL CHROMIUM

This study investigated the effects of supplemental chromium (Cr) (0 or 0.2 mg kg-1 from high-Cr yeast) on performance, carcass characteristics and tissue-mineral contents of growing-finishing steers fed com silage supplemented with either urea-com or soybean meal during the growing period and a high-grain diet during the finishing period. Ninety-six Charolais-crossed steers, divided into four treatment groups with 24 animals each, were fed for a 70-d growing period followed by a 68-d finishing period. After continuous supplemental Cr, steers were commercially slaughtered and their carcass characteristics were evaluated. Tissue samples, including loin-eye lean and rib fat, liver and kidney, were analyzed for Cr and other minerals (P, Ca, Mg, Fe, Zn and Cu). Supplemental Cr had no effects (P > 0.05) on average daily gain (ADG), dry-matter intake, (DMI), feed efficiency (ADG/DMI), and carcass characteristics, including dressing percentage, loin-eye area, backfat thickness, marbling score, kidney fat and liver weight. Proportion of lean, fat and bone in rib sections was not affected (P > 0.05) by Cr supplementation. Supplemental Cr also did not affect (P > 0.05) total-tissue Cr and other mineral concentrations. However, supplemental Cr increased (P < 0.05) the Cu level of livers in steers fed urea-com supplements during the growing period. This study showed that continuous supplementation of Cr (0.2 mg kg-1) to unstressed growing-finishing steers had no effect on carcass composition and several minerals in various tissues.