Feeding costs represent one of the highest expenditures in animal production systems. Breeding efficient animals that express their growth potential while eating less is therefore a major objective for breeders. We estimated the genetic parameters for feed intake, feed efficiency traits (residual feed intake (RFI) and feed conversion ratio (FCR)), growth and body composition traits in the Romane meat sheep breed. In these traits, selection responses to single-generation divergent selection on RFI were evaluated. From 2009 to 2016, a total of 951 male lambs were tested for 8 weeks starting from 3 months of age. They were weighed at the beginning and at the end of the testing period. Backfat thickness and muscle depth were recorded at the end of the testing period through ultrasound measurements. Feed intake was continuously recorded over the testing period using the automatic concentrate feeders. The heritability of RFI was estimated at 0.45 ± 0.08, which was higher than the heritability of FCR (0.30 ± 0.08). No significant genetic correlations were observed between RFI and growth traits. A favourable low negative genetic correlation was estimated between RFI and muscle depth (-0.30 ± 0.15), though additional data are needed to confirm these results. The selection of low RFI sires based on their breeding values led to the production of lambs eating significantly less concentrate (3% decrease in the average daily feed intake), but with the same growth as lambs from sires selected based on high RFI breeding values. We concluded that in meat sheep, RFI is a heritable trait that is genetically independent of post-weaning growth and body composition traits. A one-generation divergent selection based on RFI breeding values highlighted that substantial gains in feeding costs can be expected in selection schemes for meat sheep breeds.

中文翻译：

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罗曼公羊饲料效率的遗传参数以及对单代选择的响应。

饲养成本是动物生产系统中最高的支出之一。因此，育种能够在减少进食的同时表达其生长潜力的高效动物是育种者的主要目标。我们估算了罗曼肉羊品种的饲料摄入，饲料效率性状（残余饲料摄入量（RFI）和饲料转化率（FCR）），生长和身体成分特征的遗传参数。在这些特征中，评估了对RFI的单代发散选择的选择反应。从2009年到2016年，从3个月大开始，共对951只雄性羔羊进行了8周的测试。在测试期间的开始和结束时对它们进行称重。在测试期间结束时，通过超声测量记录背脂厚度和肌肉深度。在测试期间，使用自动浓缩饲料喂食器连续记录饲料摄入量。RFI的遗传力估计为0.45±0.08，高于FCR的遗传力（0.30±0.08）。RFI和生长性状之间没有观察到显着的遗传相关性。尽管还需要其他数据来确认这些结果，但估计RFI和肌肉深度之间的负遗传相关性较低（-0.30±0.15）。根据其育种值选择低RFI的公羊会导致生产精饲料的羔羊明显少得多（平均日采食量减少3％），但与根据RFI较高的育种值选出的公羊的羔羊生长相同。我们得出结论，在肉羊中，RFI是一种遗传性状，在遗传上与断奶后的生长和身体组成性状无关。基于RFI育种值的一代代选择表明，在肉羊品种的选择方案中，可以预期饲料成本会大幅增长。