State Key Laboratory of Grassland Agro-Ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, Gansu, China.
Agri-Food and Biosciences Institute, Hillsborough, Co Down BT26 6DR, United Kingdom.
Animal. 2021 May;15(5):100200. doi: 10.1016/j.animal.2021.100200. Epub 2021 May 23.
An accurate value for metabolizable energy (ME) requirement for maintenance (ME) is essential to enable sheep husbandry practice to reach its potential. The objectives of the study were to use calorimetry chamber data of dry ewes (Hu × thin-tail Han F1 crossbred) to develop updated ME, examine effects of substituting concentrate feed with lucerne hay on energy partitioning, and explore the relationships between energy utilization and fasting heat production (FHP). Data were collected from three experiments. In Exps. 1, 2a and 2b, lucerne hay was used to replace concentrates in three levels (0:40%, 15:25% and 30:10%), with diets containing 60% maize stover (Exp. 1), fresh rye forage (Exp. 2a) or dry rye forage (Exp. 2b). Within each experiment, diets were isoenergetic (digestible energy, DE) and isonitrogenous. Exp. 3 aimed at evaluating effects of three BW levels on nutrient utilization of dry ewes offered diets containing 60% maize stover, 15% lucerne hay and 25% concentrates. Energy metabolism data were measured using the respiration calorimeter chamber technique in all three experiments, followed by the measurement of FHP in Exps. 1, 2b and 3. The ME derived from the linear regression between energy balance (EB) and ME intake was 0.440 MJ/kg BW. The average FHP was 0.326 MJ/kg BW. The fasting metabolism, net energy requirement for maintenance (NE) and ME were estimated to be 0.336, 0.359 and 0.511 MJ/kg BW, respectively, through adjustment of FHP using fasting urinary energy output, activity allowance and efficiency of ME use for maintenance. The FHP was negatively correlated to EB/metabolic BW, ME/gross energy (GE), ME/DE, EB/GE intake and EB/ME intake, while positively correlated to HP/GE intake, HP/ME intake and CH-E/GE intake. Compared to zero lucerne hay diet, the 15% lucerne hay intake decreased HP (MJ/d), and had no negative effects on EB (MJ/d) or energy utilization efficiencies. The results indicate that nutrient requirement standards currently used across the world are likely to underestimate ME for dry ewes, and the selection of low FHP ewes for breeding has the potential to improve sheep production efficiency.
为了使绵羊养殖实践能够充分发挥潜力，准确确定维持需要的代谢能（ME）值是至关重要的。本研究的目的是使用干燥母羊（Hu×细尾寒羊 F1 杂交）的热量测定室数据来更新 ME，研究用紫花苜蓿干草替代精饲料对能量分配的影响，并探讨能量利用与空腹产热（FHP）之间的关系。本研究共进行了三个实验。在实验 1、2a 和 2b 中，用三种水平（0:40%、15:25%和 30:10%）的紫花苜蓿干草替代精饲料，饲料分别含有 60%玉米秸秆（实验 1）、新鲜黑麦饲草（实验 2a）或干黑麦饲草（实验 2b）。在每个实验中，饲料的消化能（DE）和粗蛋白含量保持相同。实验 3 旨在评估三种 BW 水平对提供 60%玉米秸秆、15%紫花苜蓿干草和 25%精饲料的干燥母羊的养分利用的影响。在所有三个实验中，均使用呼吸测热室技术测量能量代谢数据，然后在实验 1、2b 和 3 中测量 FHP。从能量平衡（EB）和 ME 摄入量之间的线性回归中得出的 ME 值为 0.440 MJ/kg BW。平均 FHP 为 0.326 MJ/kg BW。通过调整 FHP 以利用空腹尿液能量输出、活动允许量和 ME 用于维持的效率，估计空腹代谢、维持净能需求（NE）和 ME 分别为 0.336、0.359 和 0.511 MJ/kg BW。FHP 与 EB/代谢 BW、ME/总能（GE）、ME/DE、EB/GE 摄入量和 EB/ME 摄入量呈负相关，与 HP/GE 摄入量、HP/ME 摄入量和 CH-E/GE 摄入量呈正相关。与不含紫花苜蓿干草的日粮相比，15%紫花苜蓿干草的摄入量降低了 HP（MJ/d），但对 EB（MJ/d）或能量利用效率没有负面影响。结果表明，目前全球使用的营养需求标准可能低估了干燥母羊的 ME，选择 FHP 低的母羊进行繁殖有可能提高绵羊生产效率。
