Cows resulting from the first crossing of two breeds live on average 60 days longer than expected based on the genetic predisposition of the parents. They also produce an average of 235 kg of additional milk and have a shorter calving interval of about 3 days and less subclinical mastitis by more than half a percent.
This emerges from new calculations by the Animal Evaluation Unit (AEU) of the CRV cooperative of the effects of heterogeneity.
Better than parents
Heterogamy occurs when animals of different breeds are mated. Offspring resulting from crossbreeding perform better on many characteristics than would be expected based on the average genetic predisposition of the parents. This difference is called the covariance effect. The AEU section of the CRV Collaboration has calculated the outcrossing effects for a large number of traits based on the performance of large numbers of crossbreeds.
More races, more heterogeneity
The maximum heterosis effect is achieved with the first crossing of two strains. If this crossbreeding is paired with a third breed, 100 percent crossbreeding will be achieved again. But if the hybrid is mated back to one of the two original breeds, the effect of mating on the offspring is only 50 percent. In this way, it is possible to calculate the proportion of heterosis that is achieved after five generations and remains approximately stable for different hybridization strategies. For a two-way intersection, this percentage is 69 percent, for a three-way intersection 88 percent, and for a four-way intersection 94 percent.
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