Selection and genetic parameters of productivity of sheep (<i>ovis aries</i>) of the Trans-Baikal breed of the Khangil type

The study was conducted to investigate the selection and genetic parameters of productivity of fine-wool sheep of the Trans-Baikal breed of the Khangil typein order to increase the efficiency of the selection process. The relationships between the selected traits (live weight, wool yield) and the exterior and constitutional features were determined using the method of correlation and regression analysis. Of the assessed parameters, the greatest variability was observed for body weight (11.9…19.4 %), wool yield (9.9…11.1 %) and latitudinal linear measurements (8.2…12.4 %). According to the constitution indices, rams differed from ewes by greater leg length, better chest development, stronger skeleton, while ewes were characterized by a more stretched, compact and massive body with a better developed back part. Live weight and wool yield of rams were more closely associated with linear measurements than those of ewes. Live weight of both males and females correlated more strongly with chest girth (respectively +0.916, p 0.001 and +0.740, p 0.001), wool yield – with chest depth in rams (+0.737, p 0.001) and hip width in ewes (+0.469, p 0.001). In Trans-Baikal breed of the Khangil type rams, with an increase in the hip width measurement by 1 cm, it is possible to predict an increase in live weight by 5.50 kg (r = 0.839; p 0.001), in ewes with an increase in chest girth by 1 cm – by 1.04 kg (r = 0.740; p 0.001). The analysis of paired regression equations shows that the live weight of Trans-Baikal breed of the Khangil type ewes is largely determined by the linear measurement of the chest girth: in rams – 83.9 %, in ewes – 54.7 %, the influence of other factors accounts for 16.1 and 45.3 %, respectively. At the same time, in the multivariate regression models, 94.3 and 74.7 % of the change in body weight is explained by the effect of a complex of linear measurements, and the remaining share is attributed to the influence of other factors.