Effects of trace mineral supply from rumen boluses on performance, carcass characteristics, and fecal bacterial profile in beef cattle

The experiment was conducted to evaluate trace mineral supplies of copper (Cu), cobalt (Co), selenium (Se), and iodine (I) using rumen boluses (a slow-release leaching technology) on performance, carcass characteristics, and fecal bacterial profile in beef cattle. Total 36 beef Angus steers were used in a completely randomized block design and received a diet without supplementation of Cu, Co, Se, and I (NCON), a diet supplemented with Cu, Co, Se, and I (PCON), or the NCON diet with rumen boluses providing Cu, Co, Se, and I (Bolus). The experiment consisted of 8 weeks of a backgrounding, 4 weeks of a transitioning, and 12 weeks of a finishing phase. Data collected from the experiment were dry matter intake (DMI), average daily gain (ADG), feed efficiency (gain to DMI, kg/kg), and carcass data from individual animals. In the last week of the backgrounding and finishing phase, fecal samples were collected from individual animals and fecal bacterial diversity was determined. All data were analyzed using the MIXED procedure of SAS. No difference in DMI and growth performance among treatments was observed during the backgrounding phase. Interactions of treatments by week for DMI (P < 0.01) and ADG (P = 0.09) were observed during the finishing phase where DMI and ADG were greater for PCON and Bolus compared with NCON during the first 6 weeks of the finishing phase. Carcass characteristics did not differ among treatments except that Bolus had higher quality grade (P = 0.036) compared with NCON and PCON. During the backgrounding phase, the relative abundance of Bifidobacterium was greater (P = 0.026) for Bolus vs. NCON and PCON and that of Treponema was greater (P = 0.01) for PCON vs. NCON and Bolus. During the finishing phase, the ratio of Firmicutes to Bacteroidetes was lower (P = 0.032) for PCON compared with NCON and Bolus without a difference between NCON and Bolus. However, those changes in bacterial diversity during the backgrounding and finishing phases did not influence performance and carcass characteristics of beef steers. In conclusion, trace minerals of Cu, Co, Se, and I need to be provided to meet or exceed the requirements for optimal performance especially during a finishing phase and the trace mineral supply via rumen boluses may have potential to improve a carcass quality grade. In addition, fecal bacterial diversity was altered by trace mineral supply and the method of the supply.