Genetic and phenotypic correlations among linear type traits in Sahiwal cows
2008
Khan, M.A. (University of Agriculture, Faisalabad (Pakistan). Dept. of Animal Breeding and Genetics) | Khan, M.S. (University of Agriculture, Faisalabad (Pakistan). Dept. Livestock Management) | Iqbal, A. (University of Agriculture, Faisalabad (Pakistan). Dept. of Livestock Management)
The objective of the present study was to find phenotypic and genetic correlations among linear type traits in Sahiwal cows. The 15 linear type traits recommended by the International Committee for Animal Recording for dairy cattle were recorded for 310 Sahiwal cows over a period of one year at three institutional herds in Pakistan. These cows were progeny of 53 sires. Cows were recorded for the linear traits on a scale of 1-9 at the start, mid and towards end of lactation (provided cows were still in milk). A multiple trait animal model was utilized for estimation of (co)variances components. It included fixed effects of herd (three), parity group (two: 1st and later) and stage of lactation (three: start, mid and end). The random animal effect was also fitted and all the known relationships were accounted for. Phenotypic correlations among body and feet and legs traits were in low to medium range. Correlations ranged from 0.17 plus minus 0.05 between body depth and foot angle to 0.55 plus minus 0.03 between body depth and thurl width. Feet and legs traits showed very low or negative genetic correlation with body traits and among themselves. Genetic correlations among udder traits were in low to medium range. Rear udder height, for example, showed negative genetic correlation with stature, chest width and body depth. Therefore, care is needed to avoid deterioration among undesirably negatively associated traits. This information should, however, be considered preliminary because of smaller data set.
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