Effects of feeding rumen-protected Capsicum oleoresin on growth performance, health status, and total tract digestibility of growing beef cattle

Objectives were to investigate the effects of rumen-protected Capsicum oleoresin (RPC) supplementation on growth performance, health, immune and oxidative stress response, total tract digestibility and nitrogen (N) utilization of feedlot cattle. In Exp. 1 cattle were stratified by sex (steers = 24; heifers = 12) and body weight (BW; heavy, 240 +/- 38 kg; or light, 181 +/- 32 kg) and assigned to 2 treatments: no additive (control), or supplementation with 15 mg of RPC/kg of diet dry matter (DM) (15RPC). Cattle were transitioned over 21 d to a final diet of 80 % concentrate feeds and 20 % corn silage. Cattle were weighed at the start of the trial (d 0 and 1), end of diet transition (d 22), midpoint (d 49 and 50), and end of the trial (d 99 and 100). Blood was collected on d 1, 22, and 98. Records regarding treatment for sickness were used to analyze health status of the cattle. In Exp. 2, 8 steers were fed in a replicated 4 x 4 Latin Square with 4 treatments: control, and RPC at 5, 10, and 15 mg of RPC/kg of diet DM. Experimental periods consisted of 21 days of diet adaption followed by 6 days of sample and data collection. In Exp. 1, there were no effects of treatment on DM intake (DMI) or final BW. From d 1 to 50, average daily gain (ADG) was 23.3 % greater and gain to feed ratio (G:F) was 14 % greater for cattle fed RPC. There was no effect of treatment on red and white blood cells, haptoglobin, glutathione, glucose, insulin, or blood urea nitrogen. However, 76.5 % of light weight cattle fed control had fever (rectal temperature above 39.5 degrees C) on 2 or more occasions while only 21.8 % of the light weight cattle fed RPC had fever twice or more. In Exp. 2, intake, total tract apparent digestibility of DM, organic matter, crude protein and neutral-detergent fiber, and N excretion and retention were not different among treatments. In summary, supplementing RPC improved early feedlot ADG; however, ADG improvement was unrelated to DMI. In addition, nutrient utilization and digestibility did not change in Exp. 2. Changes in health status could have influenced ADG, but blood parameters related to health status were not affected by treatment. More frequent blood sampling during the critical phase of diet adaptation may help detecting earlier differences in immune status of cattle.