Quantitative genetic analysis of variability and relationship of lambs body weight traits in population of indigenous Pirot sheep

Quantitative genetic analysis of variability and relationship of lambs body weight traits in indigenous pirot sheep population are done. The examined lambs had high variability which very suitable for selection on a larger weight. There is a high and very significant correlation between the body weight of lambs with 30 and 60 days (.969 **) and the weight with 30 and 90 days (.914 **). There is also a highly significant correlation between the weights of lambs with 60 and 90 days of age (.904 **). From our research, we can see that the first month of the lamb's life is very important for the further development of the body. There is different level of correlation between weight of lambs. This gives us an idea to say that many paragenetic factors are crucial for the growth of lambs from birth to weaning. The coefficient of multiple determination (R2) is 0.845 which means that 8.45% of the lamb's body weight variance at 90 days is determined by the variance of the set of predictor variables (PI-60, 30, 1). Each increase in lamb body weight during the observed periods of age is associated with an increase in the score of depending variable PI90. In particular, any increase in lamb body weight at birth by 1 kg is associated with an increase in lamb body weight from 90 days by 0.238 kg.