CORRELATIONS BETWEEN LENGTH OF PRODUCTIVE LIFE, MILK PRODUCTION AND CONFORMATION TRAITS IN THE LITHUANIAN BLACK-AND-WHITE COWS POPULATION

Abstract

The objective of this study was to determine genetic and phenotypic correlations between length of productive life and milk production, conformation traits in Lithuanian Black-and-White cows' population. The conformations and productive live data set consisted of 6120 registered Lithuanian Black- and -White cows between years 1996 and 2007, inclusive in Lithuanian State enterprise's Agri-Information and Rural Business Center. Analysis was performed using a Weibull proportional hazard model. The following effects were included in the model - fixed: herd-year-season, sire, sire dam, age at first calving, lactation number; lactation phase, herd size, herd change; random: cow's milk production; cow's fat and protein production, herd's average milk production, herd's average fat and protein production. The results of genetic and phenotypic relationships demonstrated the milk production traits having positive influence on productive live of cows (P<0.001). The relationships between most of the conformation traits and productive live of cows were significant. The observed genetic correlations between productive life of cows and type traits are in the range of -0.034 (between productive live and teat's placement) to 0.067 (between productive live and hoot and tarsus angle); phenotypic correlations - in range of -0.312 (between productive live and depth of udder) to 0.296 (between productive live and stoutness).