Energy requirements of Texel crossbred lambs.

Two trials were conducted to determine the energy requirements of feedlot Texel crossbred lambs. In a comparative slaughter trial, thirty 11/16 Texel x 5/16 Ile de France crossbred noncastrated male lambs, weaned at 42 d of age (16.2 +/- 2.1 kg of shrunk BW; SBW), were used. Five lambs were randomly chosen and slaughtered after 10 d of experimental management and diet adaptation (baseline group). Fifteen lambs then were fed for ad libitum intake and slaughtered at 25, 30, or 35 kg of SBW. The remaining 10 lambs were randomly assigned to 2 levels of DMI, either 70 or 55% of the ad libitum intake, and were slaughtered concomitantly with lambs of the 35 kg of SBW group. Total body N, fat, and energy contents were determined. In a digestibility trial, 6 Texel x Ile de France crossbred lambs (30.4 +/- 2.6 kg of SBW) were housed in metabolic cages and used in a replicated 3 x 3 Latin square experiment to evaluate the energetic value of the diet at different feed intake levels. Net and ME requirements for maintenance were 58.6 and 91 kcal/kg(0.75) of SBW, respectively. Consequently, partial efficiency of energy use for maintenance was 0.64. Body fat content varied from 72.7 to 125.9 g/kg of empty BW, respectively, for 13.1 and 28.2 kg of empty BW. Net energy requirements for growth of lambs at 15 and 35 kg of SBW at an ADG of 250 g were 424 and 553 kcal/d, respectively. Partial efficiency of energy use for growth was 0.47. Texel x Ile de France crossbred growing lambs used in this study showed decreased nutritional requirements than those reported by most nutritional systems.