ABSTRACT

Ewe lamb live weight at first mating (7 months of age) is positively associated with reproductive performance and led to the recommendation of a minimum mating live weight of 40 kg. This experiment examined the effects of heavier mating live weight of ewe lambs on their live weight, fertility, lambing percentage and their progeny performance to weaning. Ewe lambs (n = 270) were randomly allocated to one of two treatments. The Heavy group (n = 135) was preferentially fed until mating, achieving 47.9 ± 0.36 kg, while the Control group (n = 135) had an average mating live weight of 44.9 ± 0.49 kg. Fertility, lambing percentage, ewe live weights, the survival and live weights of their progeny were recorded. There was a 28% increase in fertility and a 59% increase in lambing percentage in the Heavy group compared to the Control group. Progeny survival and live weights did not differ (P > .05) by treatment. A curvilinear relationship between fertility and ewe live weight at mating was identified, suggesting that ewe lambs should be mated at a live weight of 50–55 kg to maximise fertility and lambing percentage without reducing ewe live weight nor the progeny performance.

摘要

初次交配（7个月大）的母羊羔羊活重与生殖能力成正相关，因此建议最小交配活重为40公斤。该实验检验了母羊羔交配活重较重对它们的活重，繁殖力，羔羊百分率和后代断奶性能的影响。母羊羔（n  = 270）被随机分配给两种处理之一。重组（n  = 135）优先进食直至交配，达到47.9±0.36 kg，而对照组（n = 135）的平均交配活重为44.9±0.49公斤。记录生育力，羔羊百分比，母羊活重，后代的存活率和活重。与对照组相比，重型组的生育力提高了28％，产羔率提高了59％。后代的生存率和活体重量在治疗上没有差异（P  > 0.05）。确认了交配时的繁殖力与母羊活重之间的曲线关系，这表明应在50-55 kg的活重下交配母羊羔，以在不降低母羊活重或后代性能的情况下最大化繁殖力和羔羊百分比。