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Inbreeding and Crossbreeding Parameters for Production and Fertility Traits in Holstein, Montbéliarde and Normande Cows
Breed differences and non-additive genetic effects for milk production traits, somatic cell score (SCS), conception rate (CR) and days to first service (DFS) were estimated for Holstein × Montbéliarde and Holstein x Normande crossbreds. The Holstein breed was genetically superior for production and inferior for fertility traits to the two other breeds. Inbreeding depression caused loss of yield for production traits, a small increase in SCS and DFS, and a decrease of CR. Favorable heterosis effects were found for all traits, to such a point that F1 crossbreds can compete with Holstein cows for milk production and have a better fertility. However, recombination loss indicated that much of the F1 heterosis was lost in second and later generations of crossbreeding.
Keywords:
dairy crossbreeding
production traits
functional traits
nonadditive effect
