title: Energy requirements of Dorper crossbred ewe lambs.
abstract: The ME and NE requirements of Dorper crossbred ewe lambs grown from 35 to 50 kg BW were assessed in a comparative slaughter trial. Thirty-five ewe lambs (33.5 ± 0.6 kg BW) of F1 crosses of purebred Dorper and thin-tailed Han sheep were used: 7 lambs were slaughtered at the start of the trial to provide baseline measures of body composition and 7 lambs were fed ad libitum and slaughtered when they reached 43 kg BW to provide intermediate measures of body composition. The remaining 21 lambs were divided into 3 groups of 7 lambs each and fed a pelleted mixed diet (concentrate:roughage = 44:56, DM basis) for ad libitum intake or 65 or 45% of ad libitum intake. All 3 groups were slaughtered when the ad libitum group reached 50 kg BW. Total body energy, N, fat, ash, and moisture content were measured. In a separate trial, 15 ewe lambs (39.5 ± 0.7 kg BW) of F1 crosses of purebred Dorper and thin-tailed Han sheep were housed in metabolism cages to evaluate the ME value of the diet at each of the 3 levels of feed intake. In vivo methane production was measured by open-circuit respirometry along with the collection of all feces and urine. The daily NEm requirement of the ewe lambs was 280 kJ/kg metabolic BW (BW(0.75)) or 292 kJ/kg metabolic shrunk BW (SBW(0.75)), whereas the daily ME requirement for maintenance was 418 kJ/kg BW(0.75) or 437 kJ/kg SBW(0.75), with a partial efficiency of ME utilization for maintenance of 0.67. The NEg requirement ranged from 1.37 to 3.94 MJ/d for ADG from 100 to 250 g BW, and the partial efficiency of ME utilization for gain was 0.44. The NE and ME requirements of Dorper × thin-tailed Han crossbred ewe lambs were lower than the recommendations of the United States' nutritional system.
authors.affiliation: Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: K D
authors.initials: KD
authors.lastname: Deng
authors.forename: C G
authors.initials: CG
authors.lastname: Jiang
authors.forename: Y
authors.initials: Y
authors.lastname: Tu
authors.forename: N F
authors.initials: NF
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: T
authors.initials: T
authors.lastname: Ma
authors.forename: Y G
authors.initials: YG
authors.lastname: Zhao
authors.forename: G S
authors.initials: GS
authors.lastname: Xu
authors.forename: Q Y
authors.initials: QY
authors.lastname: Diao
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary*; D004063:Digestion; D002149:Energy Intake; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D012756:Sheep / Q000502:physiology*; D015430:Weight Gain