Genetic evaluation of linear udder and body conformation traits in Bunaji cows

Abstract

Genetic parameters for conformation traits of Bunaji cows are presented in this study. Data from 50 Bunaji cows collected between 2007 and 2008 at the Dairy Research Farm, National Animal Production Research Institute (NAPRI), Shika, Zaria was used. Analyzed conformation traits includes 7 body conformation traits: stature (ST), chest width (CW), wither height (WH), heart girth (HG), body length (BL), body depth (BD), rump width
(RW) and 7 udder conformation traits: rear udder height (RUH), rear udder width (RUW), udder depth (UD), udder cleft (UC), fore teat position (FTP), rear teat placements (RTP) and teat length (TL), both of which were measured in centimeter (cm) using measuring stick and flexible tape. The measurements were taken monthly by 3 evaluators for the complete lactation length of the cows, this resulted in 1200 cumulative records, The
estimated h2 of the linear conformation traits were between 0.203 (UD) and 0.621 (HG). The genetic correlations amongst the body conformation traits ranged from 0.116 to 0.992 while the phenotypic correlation ranged from 0.187 to 0.743. The genetic and phenotypic correlations amongst the udder conformation traits varied between – 0.538 to 0.352 and -0.257 to 0.325, respectively. The observed higher magnitude of genetic correlations than the phenotypic correlations for most of the conformation traits, coupled with the high heritability and repeatability estimate indicates that most of the conformation traits are influenced more by genetic factors rather than environmental factors; hence they can be improved with high degree of certainty through selection.