Non-Genetic Factors Affecting Birth Weight in the Lambs of Blackheads Pleven Breed

The aim of the present study was to analyze the impact of different non-genetic factors on the birth weight of 2198 lambs from the blackhead Pleven sheep breed. The results showed that lamb weight at birth ranged from 4.23 to 4.58 kg. Lambs that are born singles have 9.6% higher birth weight compared with twins (P<0.01), and females have 3.7% lower birth weight than males (P<0.01). The body condition score of ewes at birth has a moderate negative correlation on the live weight of the lambs at birth (P<0.01). The body condition scores of the ewes at birth influences the weight of the lambs at birth. Ewes with body condition score under 3 birth heavier lambs, compared with ewes with body condition score over 3 (P<0.01). Ewes with live weight over 56 kg have lighter lambs, compared to the ewes with live weight under 56 kg (P<0.01). Non-genetic factors have a high influence on the weight of the lambs at birth with the exception of the duration of gestation. This confirms the interaction of non-genetic factors influencing the weight of the lambs at birth.