Analysis of the influence of genetic and non-genetic factors on the birth weight and weaning weight of lambs

The main aim of this paper is to analyze the influence of genetic and non-genetic factors on the birth weight and weaning weight of lambs. The study was carried out on the basis of the Institute of Animal Husbandry of Steppe Regions named by M. F. Ivanov “Askania-Nova” – the National Scientific Agricultural Center in Sheep Breeding of NAAS. Birth and weaning weights data collected during a 5-vear period from 3961 lambs were used. The reproductive traits of the Ascanian fine-fleece (AC) ewes were evaluated in combination with the rams of different genotypes: Ascanian fine-fleece, Australian merino (AM) and half-bred animals (1/2AC+1/2AM). The main effect of the ram genotype and the year of lambing, the age of the ewes, the litter size, the sex of lamb and the sex ratio in twins on the birth weight and weaning weight of lambs was analysed using one-way ANOVA. Differences between years of the 5-year period were highly significantly (P < 0.001) for all lamb traits studied. The effects of the environmental factor (year of lambing) on the birth weight and weaning weight of lambs represented 27.2 and 15.2 per cent of the total variance, respectively. The ram-group effects, which are mainly genetic differences, were highly significant (P