The objective of this trial was to evaluate the effect of feed restriction during a grazing period of 104 days (phase I) on intake, feed conversion, and digesta load as well as body weight (BW) change and weights of carcass and non-carcass components during a feedlot period (phase II) in crossbred steers. Thirty nine crossbred Holstein-Gyr steers averaging 19.3±5.1 months of age and 202.0±49.1 kg of BW at the beginning of the study were used. Animals were assigned to one of the following three treatments: 1 - control - ad libitum grazing in phase I and ad libitum concentrate in phase II (nine animals); 2 - compensatory growth - restricted grazing in phase I and ad libitum concentrate in phase II (15 animals); or 3 - maintenance - restricted grazing in phase I and protein and energy supplementation 15% above maintenance in phase II (15 animals). At 1, 28, and 112 days of feedlot, three animals from treatments 1, 2 and 3 were slaughtered. In addition, three animals from treatments 2 and 3 were also slaughtered at 56 and 84 days of feedlot. Animals from the compensatory growth treatment gained more BW than those from the control during the first 28 days of feedlot because of the greater weight gain of non-carcass components. However, carcass weight gain did not differ between both treatments. Gut fill as percentage of BW decreased in all three treatments when animals were fed concentrate in phase 2 but no significant differences were observed across treatments. Animals on control and compensatory growth treatments had improved feed conversion during the first 28 days of feedlot, which was associated to greater intake either expressed per unit of metabolic size or as percentage of BW.
carcass; digesta; feed conversion; weight gain
