Management Strategies to Improve Gastrointestinal Health and Productivity of Native And Dairy-Derived Steers Fed in Confinement

The objective of this dissertation was to evaluate strategies to mitigate metabolic disorders in confinement fed steers. The first study was conducted on yearling beef steers to investigate the effect of a rumen buffer, calcium magnesium carbonate (CMC), when fed with or without tylosin phosphate (TYL), on growth performance, rumination activity and liver abscess prevalence. Supplementation of a rumen buffer was not an effective alternative to a feed-grade antimicrobial for the control of liver abscesses in beef steers. Supplementation of CMC reduced DMI, thus negatively influencing BW and ADG. No associative effects of CMC and TYL were observed for any growth, carcass responses, or prevalence of liver abscesses. Supplementation of TYL reduced the rate of liver abscesses by 9.8 percentage points, confirming the efficacy of TYL as a control mechanism. Study two evaluated the effect of increasing length of time spent on a high-forage receiving diet on growth performance, carcass characteristics, rumination activity, sera metabolites, and prevalence of liver abscesses in lightweight dairy-crossbred steers. Greater time spent on a high-forage receiving ration reduced DMI, ADG, and BW during the first 97 d, but did not alter entire-feeding performance or carcass characteristics. Rumination activity was positively associated with time spent on the receiving ration. The results from these experiments indicate that alternatives to feed-grade antimicrobials for the control and prevention of liver abscesses warrant further research regarding dosage and effects on rumen kinetics. Furthermore, increasing time spent on a high forage receiving ration depressed early feedyard-growth performance, but did not alter cumulative growth performance and efficiency, but may be a promising strategy to reduce the prevalence of abscessed livers at harvest. Strategies investigated in this dissertation may provide producers with the necessary knowledge to make informed decisions regarding roughage use, particularly in Angus × Holstein steers, and confirms the efficacy of tylosin phosphate to reduce rates of liver abscesses in cattle.