Recording feed intake and thus feed efficiency in ruminants is challenging. Hence, there is a need to establish indicator traits that can capture the individual variation in feed efficiency, without requiring individual feed intake recordings. This study aimed to explore whether the methodology established in salmon using individual indicator traits for feed efficiency based on stable isotope profiling could be transferred to lambs since the product for both species is meat. We used a total mixed ration based on maize silage to record the individual indicator traits for feed efficiency. The experiment was done with twelve weaned female lambs of the Norwegian White Sheep grouped equally in three, one group fed a total mixed ration enriched with ¹³C for 42 days, the second group grazed for 21 days and then fed the total mixed ration for 21 days, and the third group grazed for 42 days. The latter group was included to establish a baseline value for the stable isotope percentage in the back and thigh muscle tissues. Recording of ¹³C in the back muscle of the animals in the first two groups, resulted in a phenotypic correlation as large as 0.92 between individual feed conversion ratio and the individual indicator traits for feed efficiency based on stable isotope profiling. An assessment through individual indicator traits would be independent of the recording of individual feed intake.

记录采食量以及反刍动物的采食效率是一项挑战。因此，需要建立可以捕获饲料效率的个体变化而无需个体饲料摄入量记录的指标特征。这项研究旨在探讨在鲑鱼中建立的使用基于稳定同位素分析的饲料指标的个体指标性状建立的方法是否可以转移到羔羊上，因为这两种物种的产品都是肉。我们使用基于玉米青贮饲料的总混合日粮来记录饲料效率的各个指标性状。实验是用十二只挪威白羊断奶雌羊平均分成三组进行的，一组喂食的混合日粮中富含^13种C持续42天，第二组放牧21天，然后喂食总混合日粮21天，第三组放牧42天。包括后一组以确定背部和大腿肌肉组织中稳定同位素百分比的基线值。在前两组动物的背部肌肉中记录到¹³ C，导致个体饲料转化率与基于稳定同位素分析的饲料效率个体指标性状之间的表型相关性高达0.92。通过单个指标性状进行的评估将独立于单个饲料摄入量的记录。