Evaluation of a Low-Moisture, Molasses-Based Block Containing Organic Sources of Trace Minerals and a Saccharomyces cerevisiae Fermentation Culture during the Feedlot Receiving Phase on Growth Performance, Efficiency of Dietary Net Energy Utilization, and Liver Trace Mineral Status in Newly Weaned Steer Calves

The objective of this study was to evaluate the growth performance responses and liver trace mineral status newly weaned steer calves offered a low-moisture, molasses-based block “stress tub” containing organic sources minerals Saccharomyces cerevisiae fermentation culture during first 21-d 42-d feedlot receiving phase. Newly weaned, single source Charolais x Angus (n = 46; body weight [BW] 240; SEM 1.0 kg) were used in randomized complete design experiment. On d -1 all steers individually weighed morning for allotment purposes, then stratified by initial BW allotted one ten pens 4 5 per pen; treatment) that randomly assigned 1 2 treatments: 1) no cooked molasses “stress” tub (Con) or 2) ad libitum access (Stress Tub; Purina Animal Nutrition, St. Louis, MO, USA) (Tub). Steers their within 36 h weaning, introduced approximately 24 post arrival. During 14-d on feed, intake managed feed calls accommodate adaptation diet. Following period, bunks using slick bunk management approach. Tub disappearance monitored daily. Liver biopsies steers/pen) collected 7, 21, 42 determination Co, Cu, Mn, Zn. From 0 21 42, from treatment consumed greater (p ≤ 0.01) amounts Zn compared with those Con treatment. A × day interaction hepatic concentrations Co 0.09), Cu 0.01), noted. had Con. Cu; similar between treatments 0.83). however, did not differ ≥ 0.34). experiment, gain efficiency enhanced 0.03) 25.0% Cumulative ADG, DMI, dietary NE utilization G:F 0.14) treatments. It is concluded use stress tubs does influence overall value diet period. Stress consumption increased stores period throughout