Effect of Feeding Different Protein and Energy Supplements on Performance and Health of Beef Calves During the Backgrounding Period

Newly received or weaned calves are highly susceptible to the incidence of bovine respiratory disease. In addition to high levels of stress, decreased feed intake and exposure to foreign antigens result in increased morbidity and possibly death losses. Four backgrounding trials were conducted to examine the effects of protein and energy supplements to stressed calves consuming different forages. Body weights, rectal temperatures and blood samples were taken on d 0, 7, 14, 28 and 42. Supplements consisted of corn or mixtures of corn and soybean meal. In trial 1, 48 heifers (average BW = 219 kg) fed fescue hay in drylot, were allotted to four treatments: no supplement, 15% CP supplement (0.5% BW), 15% CP supplement (1.0% BW) and 30% CP supplement (0.5% BW). Supplemented heifers had higher (P<0.05) ADG than unsupplemented heifers by 42 d. Heifers fed the 30% CP supplement had higher (P<0.05) plasma urea-N by d 42. In trial 2 (pasture study 1), 36 steers (average BW = 217 kg) grazed stockpiled tall fescue and were allotted to three treatments: no supplement, a 15% CP supplement (0.5% BW), and a 15% CP supplement (1.0% BW). After wk 1, ADG was lower (P<0.05) for supplemented calves. At the end of the trial, steers supplemented at 0.5% BW had higher (P<0.05) ADG than steers supplemented at 1.0% BW. Glutathione peroxidase levels were lower (P<0.05) for supplemented steers on d 28. For trial 3 (pasture study 2), 48 steers (average BW = 202 kg) grazed stockpiled tall fescue and were allotted to three treatments: no supplement, corn (1% BW), and 15% CP supplement (1% BW). After wk 1, ADG was higher (P<0.05) for steers supplemented with corn. Steers supplemented with 15% CP supplement had the lowest (P<0.05) ADG after 7 d. At d 42, supplemented steers gained faster (P<0.05) than unsupplemented steers. For trial 4 (pasture study 3), 48 steers (average BW = 202 kg) grazed stockpiled tall fescue or fescue-alfalfa and were allotted to two treatments: no supplement and a 15% CP supplement (0.5% BW). During wk 1, steers grazing fescue had higher (P<0.05) ADG than steers grazing fescue-alfalfa. During wk 1, supplemented steers had a higher (P<0.05) morbidity scores. At d 42, ADG was higher (P<0.05) for supplemented steers. No consistent differences were detected in forage and blood serum mineral concentrations in all trials. Glutathione peroxidase activity increased (P<0.05) for all trials on d 14, regardless of supplementation. Supplementation improved ADG by d 42 but did not affect overall health status of calves in all trials.