Agri-Food and Biosciences Institute, Hillsborough, County Down, BT26 6DR, UK.
State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China.
Animal. 2020 Feb;14(2):295-302. doi: 10.1017/S1751731119002064. Epub 2019 Sep 26.
There is evidence indicating that using the current UK energy feeding system to ration the present sheep flocks may underestimate their nutrient requirements. The objective of the present study was to address this issue by developing updated maintenance energy requirements for the current sheep flocks and evaluating if these requirements were influenced by a range of dietary and animal factors. Data (n = 131) used were collated from five experiments with sheep (5 to 18 months old and 29.0 to 69.8 kg BW) undertaken at the Agri-Food and Biosciences Institute of the UK from 2013 to 2017. The trials were designed to evaluate the effects of dietary type, genotype, physiological stage and sex on nutrient utilization and energetic efficiencies. Energy intake and output data were measured in individual calorimeter chambers. Energy balance (Eg) was calculated as the difference between gross energy intake and a sum of fecal energy, urine energy, methane energy and heat production. Data were analysed using the restricted maximum likelihood analysis to develop the linear relationship between Eg or heat production and metabolizable energy (ME) intake, with the effects of a range of dietary and animal factors removed. The net energy (NEm) and ME (MEm) requirements for maintenance derived from the linear relationship between Eg and ME intake were 0.358 and 0.486 MJ/kg BW0.75, respectively, which are 40% to 53% higher than those recommended in energy feeding systems currently used to ration sheep in the USA and the UK. Further analysis of the current dataset revealed that concentrate supplement, sire type or physiological stage had no significant effect on the derived NEm values. However, female lambs had a significantly higher NEm (0.352 v. 0.306 or 0.288 MJ/kg BW0.75) or MEm (0.507 v. 0.441 or 0.415 MJ/kg BW0.75) than those for male or castrated lambs. The present results indicate that using present energy feeding systems in the UK developed over 40 years ago to ration the current sheep flocks could underestimate maintenance energy requirements. There is an urgent need to update these systems to reflect the higher metabolic rates of the current sheep flocks.
有证据表明，目前英国采用的能量供给系统来定量现有的绵羊群体可能低估了它们的营养需求。本研究的目的是通过为当前的绵羊群体制定更新的维持能量需求来解决这个问题，并评估这些需求是否受到一系列饲粮和动物因素的影响。本研究使用的数据来自于英国农业食品和生物科学研究所于 2013 年至 2017 年期间进行的五项绵羊（5 至 18 月龄，体重 29.0 至 69.8 千克）试验的数据。这些试验旨在评估饲粮类型、基因型、生理阶段和性别对养分利用和能量效率的影响。在个体热量计室中测量能量摄入和能量输出数据。能量平衡（Eg）是通过总能量摄入减去粪便能量、尿液能量、甲烷能量和产热的总和计算得到的。使用受限最大似然分析对数据进行分析，以建立 Eg 或产热与可代谢能（ME）摄入之间的线性关系，同时去除一系列饲粮和动物因素的影响。由 Eg 与 ME 摄入之间的线性关系得出的维持净能（NEm）和 ME（MEm）需求分别为 0.358 和 0.486MJ/kgBW0.75，比目前用于定量美国和英国绵羊的能量供给系统中推荐的分别高 40%至 53%。对当前数据集的进一步分析表明，浓缩饲料补充、 sire 类型或生理阶段对得出的 NEm 值没有显著影响。然而，母羊的 NEm（0.352 比 0.306 或 0.288MJ/kgBW0.75）或 MEm（0.507 比 0.441 或 0.415MJ/kgBW0.75）比公羊或去势羊的 NEm 或 MEm 高。本研究结果表明，在英国使用 40 多年前制定的现行能量供给系统来定量当前的绵羊群体可能会低估维持能量需求。迫切需要更新这些系统，以反映当前绵羊群体更高的代谢率。
