Influence of inbreeding on variability, contingency and heritability of signs
Inbreeding is one of the important methods used for consolidation of animal hereditary features, creation new breeds and improvement existing breeds, types and lines. The conducted researches in 7 herds of black and mottle cattle breeding plants of Udmurt Republic on the basis of data analysis about origin and productivity from the form 2-MOL in recent years revealed that 5.9% 17.5% cows from total number of studied animals were received as a result of related selection. Classifying inbreeding cases by the Push-Shaporuzh standard method the animals received as a result of usage of different inbreeding degrees (distant, moderate, close, very close or incest) and inbreeding types (simple, complicated, complex) were distinguished. The cases of distant inbreeding in different farms vary from 16.8% to 51.9%, moderate inbreeding from 32.6% to 65.7%, close inbreeding from 2% to 22.3%, and very close inbreeding from 1.2% to 8.8%. Frequency of simple inbreeding cases in different herds vary from 80% to 95.7% from total number of inbreeding cows, complicated inbreeding from 1.2% to 11.2% cases, and complex inbreeding from 1.5% to 13.8% cases. Analysis of signs variability showed that cows received with inbreeding application in the majority of herds possess smaller milk yield variability both in comparison with outbreeding herd mates and outbreeding semi-sisters. Coefficient of milk yield variation of inbreeding cows in different farms is 0.7% -6.6% than outbreeding herd mates and 0.4%-4.3% lower in comparison with outbreeding semi-sisters. Coefficient of milk yield heritability of inbreeding cows in different farms varies from 0.28% to 0.8%, as for outbreeding cows it varies from 0.27% to 0.8%.