Genetic parameters of feed efficiency and feed intake for dairy cattle fed ad libitum

Persaud, P.; Simm, G.; Hill, W.G.

Proceedings of the 4th World Congress on Genetics applied to Livestock Production, Edinburgh 23-27 July 1990 XIV Dairy cattle genetics and breeding, adaptation, conservation: 237-240

1990


Accession: 002117930

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Abstract
Records on feed conversion efficiency, feed intake, milk yield, fat + protein yield and mean live weight of cows, fed ad lib., were analysed by Restricted Max. Likelihood, fitting an animal model with repeat lactations as an additional random effect. Univariate analyses were done after appropriate canonical transformation of the traits. Estimates of hsuperscript 2 for feed conversion efficiency and feed intake to 26-wk of lactation were 0.13+or-0.09 and 0.37+or-11 resp., and 0.13+or-0.12 and 0.52+or-0.14 to 38-wk. Genetic correlations of milk production traits with feed conversion efficiency ranged from 0.44 to 0.61, and those of milk production traits with feed intake from 0.32 to 0.74. The correlations were lower for a 26-wk lactation than for 36 wk. The genetic correlation of mean live weight with feed conversion efficiency was -0.81 and -0.82 for the 2 periods resp., and that of live weight with feed intake 0.34 and 0.45. The results indicate that, under ad lib. feeding, selection for milk yield may not result in high correlated responses in feed conversion efficiency.