Johnson Patricia L, Hickey Sharon, Knowler Kevin, Wing Janine, Bryson Brooke, Hall Melanie, Jonker Arjan, Janssen Peter H, Dodds Ken G, McEwan John C, Rowe Suzanne J
Invermay Agricultural Centre, AgResearch Ltd., Mosgiel, New Zealand.
Ruakura Research Centre, AgResearch Ltd., Hamilton, New Zealand.
Front Genet. 2022 Aug 16;13:911639. doi: 10.3389/fgene.2022.911639. eCollection 2022.
There is simultaneous interest in improving the feed efficiency of ruminant livestock and reducing methane (CH) emissions. The relationship (genetic and phenotypic) between feed efficiency (characterized as residual feed intake: RFI) and greenhouse gases [methane (CH) and carbon dioxide (CO)] traits in New Zealand (NZ) maternal sheep has not previously been investigated, nor has their relationship with detailed estimates of body composition. To investigate these relationships in NZ maternal sheep, a feed intake facility was established at AgResearch Invermay, Mosgiel, NZ in 2015, comprising automated feeders that record individual feeding events. Individual measures of feed intake, feeding behavior (length and duration of eating events), and gas emissions (estimated using portable accumulation chambers) were generated on 986 growing maternal ewe lambs sourced from three pedigree recorded flocks registered in the Sheep Improvement Limited database (www.sil.co.nz). Additional data were generated from a subset of 591 animals for body composition (estimated using ultrasound and computed tomography scanning). The heritability estimates for RFI, CH, and CH/(CH+CO) were 0.42 ± 0.09, 0.32 ± 0.08, and 0.29 ± 0.06, respectively. The heritability estimates for the body composition traits were high for carcass lean and fat traits; for example, the heritability for visceral fat (adjusted for body weight) was 0.93 ± 0.19. The relationship between RFI and CH emissions was complex, and although less feed eaten will lead to a lowered absolute amount of CH emitted, there was a negative phenotypic and genetic correlation between RFI and CH/(CH+CO) -0.13 ± 0.03 and -0.41 ± 0.15, respectively. There were also genetic correlations, that were different from zero, between both RFI and CH traits with body composition including a negative correlation between the proportion of visceral fat in the body and RFI (-0.52 ± 0.16) and a positive correlation between the proportion of lean in the body and CH (0.54 ± 0.12). Together the results provide the first accurate estimates of the genetic correlations between RFI, CH emissions, and the body composition (lean and fat) in sheep. These correlations will need to be accounted for in genetic improvement programs.
人们同时关注提高反刍家畜的饲料效率和减少甲烷（CH）排放。此前尚未研究过新西兰（NZ）母羊的饲料效率（以剩余采食量：RFI表征）与温室气体[甲烷（CH）和二氧化碳（CO）]性状之间的关系（遗传和表型关系），也未研究过它们与详细身体组成估计值之间的关系。为了研究NZ母羊中的这些关系，2015年在新西兰莫斯吉尔市因弗梅的农业研究中心建立了一个采食量设施，其中包括记录个体采食事件的自动喂食器。对来自绵羊改良有限公司数据库（www.sil.co.nz）中注册的三个有系谱记录的羊群的986只生长中的母羊羔羊进行了个体采食量、采食行为（采食事件的时长和持续时间）和气体排放（使用便携式累积室估算）的测量。从591只动物的子集中获取了额外的身体组成数据（使用超声和计算机断层扫描估算）。RFI、CH和CH/（CH+CO）的遗传力估计值分别为0.42±0.09、0.32±0.08和0.29±0.06。身体组成性状的遗传力估计值在胴体瘦肉和脂肪性状方面较高；例如，内脏脂肪（经体重调整）的遗传力为0.93±0.19。RFI与CH排放之间的关系很复杂，虽然采食的饲料减少会导致CH排放的绝对量降低，但RFI与CH/（CH+CO）之间存在负表型和遗传相关性，分别为-0.13±0.03和-0.41±0.15。RFI和CH性状与身体组成之间也存在非零的遗传相关性，包括身体内脏脂肪比例与RFI之间的负相关（-0.52±0.16）以及身体瘦肉比例与CH之间的正相关（0.54±0.12）。这些结果共同首次准确估计了绵羊中RFI、CH排放与身体组成（瘦肉和脂肪）之间的遗传相关性。在遗传改良计划中需要考虑这些相关性。
