Genetic parameters for type traits in the French Holstein breed based on a multiple-trait animal model

Abstract

Genetic parameters for 15 linear type traits and milking ease score in the French Holstein breed were estimated by Restricted Maximum Likelihood using a multiple-trait animal model. The analysis was based on 28738 cows, daughters of at least 3 generations of AI Holstein sires and distributed over 16 samples of about 1800 observations (i.e., 6000 animals when nonrecorded relatives are included) The fixed effects considered in the model included age at calving, stage of lactation, herd-round-classifier and group of unknown parents. The genetic value of base sires were either treated as random, or fixed for sires with at least 10 daughters. Treating sires as fixed increased the heritabilities for udder traits while heritabilities of size traits and most genetic correlations were stable or slightly decreased. Most udder traits were rather highly correlated and exhibited heritabilities varying from 0.23 (Teat direction rear) to 0.35 (Udder-hocks distance). All size traits were very highly correlated (0.69 to 0.97) with heritabilities from 0.25 (Chest width) to 0.47 (Height at sacrum). The heritability of Rear legs side was found to be very low (0.07). These parameters are used in the multiple-trait animal model evaluation of type traits in the French Holstein breed.