NUTRITIONAL MANAGEMENT STRATEGIES TO ALTER PERFORMANCE, HEALTH, AND RUMINATION CHARACTERISTICS DURING THE FEEDLOT RECEIVING PERIOD
Feeder cattle procured through auction market channels experience multiple stressors prior to feedlot arrival. Once at the feedlot, cattle enter a novel environment where they are exposed to new feedstuffs and water sources and are frequently comingled. These environmental factors contribute to physiological stress, which is associated with low feed intake and is a predisposing factor to bovine respiratory disease. Through this process cattle can become dehydrated and may enter a negative energy balance. Addressing hydration and energy requirements more rapidly at feedlot arrival may reduce morbidity and improve performance. Therefore 3 studies were conducted to evaluate 2 management strategies. Study 1 evaluated the effect of oral hydration therapy at feedlot arrival on health and performance during a 56-d receiving period. In study 1, experiment 1 (n=664 high-risk heifers,197.1 ± 5.8 kg) and experiment 2 (n= 297 high-risk bulls and steers, 188.9 ± 19.1 kg) assessed oral hydration therapy (0.57 L of water/ 45.4 kg BW) at feedlot arrival compared to a negative control. This study suggested improved performance and DMI in cattle receiving oral hydration therapy, however health outcomes were not improved. In study 2 a sub set of the cattle from experiment 2 were fitted with a 3-axis accelerometer collar (n = 58) and rumen bolus (n = 33) to quantify oral hydration therapy effects on activity, rumination, rumen pH and rumen temperature. Oral hydration therapy cattle had an earlier peak rumen temperature suggesting a physiological modification enabling a more pronounced inflammatory response. From this sub-set, cattle treated at least once for bovine respiratory disease (BRD) were retrospectively compared to non-treated cohorts. Cattle treated for BRD had reduced activity and rumination, as well as increased rumen temperatures and altered rumen pH. Differences in activity and rumination may be useful for early BRD detection. In study 3, 36 auction derived steers (284 ± 11 kg) were used to compare 3 receiving period nutritional management strategies including a traditional lower energy density diet, a high energy density diet, or a high energy density diet supplemented with long stem hay every 3rd day. There were no differences in performance due to nutritional management strategy. Cattle fed the high energy density ration had a greater rumen temperature following initial viral vaccination, and decreased rumination compared to the lower energy density ration treatment. There were minimal differences in rumen pH likely due to large animal to animal variation. These results suggest feeding higher energy density diets upon feedlot arrival may be a viable option, however this needs to be validated in a pen fed setting where greater daily intake variation is probable.