Selection and genetic parameters of sheep of the Aginskaya breed of the Zugalay type

The results of the study of selectable traits, exterior-constitutional features of medium wool sheep of the Aginskaya breed of the Zugalay type are presented. The data of correlation-regression, variance analysis are given, according to the results of which paired and multifactor regression models have been designed. Body weight (6.4–12.6%), down length (19.3–19.7%) and awn length (13.1–16.9%) and cannon bone girth (9.1%) are characterized by the greatest variability in the studied sheep. In terms of physique indices, rams are distinguished by longer legs, better breast development, stronger bones, ewe lambs are distinguished by a more stretched, bunched and massive body with a better developed hind part. Correlation analysis of the breeding traits with external body parts indicates that live weight and wool clip in rams has a closer correlation with linear measurements in comparison with ewe lambs. In both males and females, live weight was more strongly correlated with the width in the dippers, wool clip – with the width at hips in rams, in ewe lambs the relationship was weak or practically absent. Linear regression coefficients indicate that live weight and wool clip gain in rams are predicted by an increase per unit in hip width (4.37 abs. gain; r = 0.824; p < 0.001 and 0.13 abs. gain; r = 0.792; p < 0.001). The coefficient of determination showed that in rams the changes in live weight and wool clip by 67.9 and 62.8% were explained by the width at hips, the influence of other factors – 32.1 and 37.2%, respectively. In multifactor regression models, 90.3 and 78.0% of changes in body weight and wool clip in rams are explained by the influence of a complex of linear measurements, in ewe lambs – by 25.7 and 17.5%, respectively, the remaining share is attributed to the influence of other factors, respectively.