Concentrate supplementation effects on the performance of early weaned calves grazing Tifton 85 bermudagrass

Early weaning of calves (Bos sp.) may increase pregnancy rates of primiparous beef cows; however, there is little information On nutritional management of the calf. The objective of this study was to evaluate calf responses to dietary supplement level [10, 15, and 20 g kg(-1) of calf body weight (BW)] when 'Tifton 85' bermudagrass (Cynodon sp.) was the summer component of a pasture-based system for raising early weaned calves. Supplement contained 146 and 700 g kg(-1) of crude protein (CP) and total digestible nutrients (TDN), respectively. Soils were Adarnsvitle and Sparr sands. Pastures were rotationally stocked using a 7-d grazing and 14-d rest period. A variable stocking rate was used to maintain similar herbage allowances across treatments. There were no differences among treatments in pregraze herbage mass, herbage accumulation rate, or herbage CP and in vitro digestible organic matter (IVDOM) concentrations. Average daily gain (ADG, 0.52-0.65 kg), stocking rate [SR, 11.1-13.7 animal units (AU) ha(-1)], and liveweight gain (LWG, 1080-1550 kg ha-1) increased linearly, but grazing time decreased linearly from 193 to 147 min d(-1) as Supplementation increased from 10 to 20 g kg(-1). Income (the value of calf gain - purchase cost of concentrate ha(-1)) was greater for the 15 g kg-1 BW treatment than the average of the 10 and 20 g kg(-1) treatments. Gains of 0.65 kg d(-1) were achieved when early weaned calves were fed concentrate at 15 g kg(-1) BW while grazing Tifton 85 pastures that were managed to provide high nutritive value forage.