GENETIC EVALUATION OF JERSEY CROSSBRED CATTLE. NORTH EASTERN AGRO-CLIMATIC ZONE OF TAMIL NADU

      Аннотация: Jersey x Red Sindhi crossbred cows were evaluated for various productionand reproduction traits in the north-eastern agro-climatic zone of Tamil Nadu. Thestudy was based on the data on 355 Jersey x Red Sindhi crossbred cowsmaintained at the Post-Graduate Research Institute in Animal Sciences,Kattupakkam, Tamil Nadu for the period from 1985 to 2014 (30 years).The effect of various non-genetic factors including period of birth, seasonof birth, period of calving, season of calving and parity were analysed through least-squares analyses by using univariate General Linear Model (GLM). Thedifferent (co)variance components for calculation of genetic parameters were estimated using Restricted Maximum Likelihood Method (REML) by fitting an animal model.The overall least-squares means (± SE) of age at first service, age at first calving, weight at first calving, 180-day milk yield, 305-day milk yield, lactationlength, total lactation milk yield, peak yield, days to attain peak yield, milk yield per day of lactation length (MYLL), milk yield per day of calving interval(MYCI), service period, calving interval, dry period and number of services perconception were estimated.

Ключевые слова: Jersey crossbred cows, performance, Lifetime traits, Heritability, Repeatability, genetic correlation