Sheep production in southern Australia (particularly south west Victoria) is based increasingly on the Maternal Composite ewe, a self-replacing stable crossbred. Breeding programs have focussed on maternal traits such as reproduction and lamb growth. Understanding the variability, range and correlations between the traits of residual feed intake (RFI), feed intake (dry matter intake, DMI), growth rate and methane (CH4) emissions within the Maternal Composite ewe flock is essential to development of selection parameters that improve feed efficiency and reduce environmental impact. Sheep and cattle with low RFI (more efficient) have been observed to produce less CH4 than animals with high RFI. Selecting for animals with improved RFI may enable producers to improve the enterprise productivity while decreasing greenhouse gas emissions. Using automated feeders, feed intake, liveweight and growth rate of Maternal Composite ewes (n = 505) at three different ages (post-weaning, hogget and adult) were measured over 42 days and used to estimate residual feed intake (RFI) as a measure of feed efficiency. Methane emissions were determined twice during each RFI test period via portable accumulation chambers (PACs). During the feed intake test period, ewes were allowed ad libitum access to feed and their liveweight was recorded 3 times weekly. Daily dry matter intake varied by up to 2.1 kg DM/day between animals. Residual feed intake was phenotypically strongly correlated with DMI for all birth year and age group combinations. Within age groups, there were significant phenotypic correlations between measured traits (DMI, growth rate, RFI and CH4 emissions). However, these observed phenotypic relationships were not consistent at post-weaning, hogget or adult ages. Apart from one age by birth year combination, the relationship between CH4 emissions and RFI was not significant. This data suggests that there is enough variation in the Maternal Composite population for selection based on RFI to improve feed efficiency however, there was insufficient evidence of correlations between RFI and CH4 emissions to determine conclusively if improvements in RFI would also reduce CH4 emissions. The strong, consistent correlations between DMI and RFI suggest that a short-term measure of feed intake, coupled with a measure of animal liveweight (or mature weight) could potentially be used as an alternative measure of feed efficiency.

中文翻译：

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断奶后、生猪和成年母羊的采食量、剩余采食量和甲烷排放量之间的相关性

澳大利亚南部（尤其是维多利亚州西南部）的绵羊生产越来越多地基于母性复合母羊，这是一种自我替换的稳定杂交种。育种计划侧重于母性特征，如繁殖和羔羊生长。了解母羊复合母羊群中剩余饲料摄入量 (RFI)、饲料摄入量（干物质摄入量，DMI）、生长速率和甲烷 (CH4) 排放量之间的可变性、范围和相关性对于开发选择参数至关重要提高饲料效率并减少对环境的影响。已经观察到低 RFI（更有效）的绵羊和牛比高 RFI 的动物产生更少的 CH4。选择具有改进 RFI 的动物可以使生产者提高企业生产力，同时减少温室气体排放。使用自动喂食器，在 42 天内测量了三个不同年龄（断奶后、小猪和成年）的母性复合母羊（n = 505）的采食量、活重和生长率，并用于估计剩余采食量（RFI）作为饲料效率的衡量标准。在每个 RFI 测试期间，通过便携式聚积室 (PAC) 测定了两次甲烷排放量。在采食量试验期间，母羊可以随意采食，每周记录3次活重。动物之间的每日干物质摄入量变化高达 2.1 kg DM/天。对于所有出生年份和年龄组组合，剩余采食量在表型上与 DMI 密切相关。在年龄组中，测量的性状（DMI、增长率、RFI 和 CH4 排放）之间存在显着的表型相关性。然而，这些观察到的表型关系在断奶后、小猪或成年时不一致。除了按出生年份组合一个年龄外，CH4 排放量与 RFI 之间的关系并不显着。该数据表明，基于 RFI 进行选择以提高饲料效率的母体复合种群中有足够的变异，但是，没有足够的证据表明 RFI 和 CH4 排放之间存在相关性，无法最终确定 RFI 的改进是否也会减少 CH4 排放。DMI 和 RFI 之间强烈、一致的相关性表明，饲料摄入量的短期衡量标准与动物活重（或成熟体重）的衡量标准相结合，可能被用作饲料效率的替代衡量标准。除了按出生年份组合一个年龄外，CH4 排放量与 RFI 之间的关系并不显着。该数据表明，基于 RFI 进行选择以提高饲料效率的母体复合种群中有足够的变异，但是，没有足够的证据表明 RFI 和 CH4 排放之间存在相关性，无法最终确定 RFI 的改进是否也会减少 CH4 排放。DMI 和 RFI 之间强烈、一致的相关性表明，饲料摄入量的短期衡量标准与动物活重（或成熟体重）的衡量标准相结合，可能被用作饲料效率的替代衡量标准。除了按出生年份组合一个年龄外，CH4 排放量与 RFI 之间的关系并不显着。该数据表明，基于 RFI 进行选择以提高饲料效率的母体复合种群中有足够的变异，但是，没有足够的证据表明 RFI 和 CH4 排放之间存在相关性，无法最终确定 RFI 的改进是否也会减少 CH4 排放。DMI 和 RFI 之间强烈、一致的相关性表明，饲料摄入量的短期衡量标准与动物活重（或成熟体重）的衡量标准相结合，可能被用作饲料效率的替代衡量标准。该数据表明，基于 RFI 进行选择以提高饲料效率的母体复合种群中有足够的变异，但是，没有足够的证据表明 RFI 和 CH4 排放之间存在相关性，无法最终确定 RFI 的改进是否也会减少 CH4 排放。DMI 和 RFI 之间强烈、一致的相关性表明，饲料摄入量的短期衡量标准与动物活重（或成熟体重）的衡量标准相结合，可能被用作饲料效率的替代衡量标准。该数据表明，基于 RFI 进行选择以提高饲料效率的母体复合种群中有足够的变异，但是，没有足够的证据表明 RFI 和 CH4 排放之间存在相关性，无法最终确定 RFI 的改进是否也会减少 CH4 排放。DMI 和 RFI 之间强烈、一致的相关性表明，饲料摄入量的短期衡量标准与动物活重（或成熟体重）的衡量标准相结合，可能被用作饲料效率的替代衡量标准。