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Predicting the correlation between purebreds and crossbreds without data on crossbreds

Published on
March 26, 2021

The genetic correlation between performance of purebreds and crossbreds is a key parameter in breeding programs that rely on crossbreeding, such as those of pig and poultry. This correlation determines to what extend genetic progress in purebred breeding populations is transferred to their crossbred descendants in commercial farms. Estimating the purebred-crossbred genetic correlation usually requires data on crossbreds, which can be difficult and costly. Wageningen researchers therefore developed formulas that can predict the correlation based only on data from the purebred lines.

The genetic correlation between purebreds and crossbreds (rpc)

Crossbreeding is the practice of mating animals from genetically distinct purebred lines to produce crossbreds, and is widely adopted in pig and poultry breeding. Genetic progress is realized in the purebred lines, while the aim of the breeding goal is to improve crossbred performance. The extent to which genetic progress in the parental lines is transferred to their crossbred descendants is determined by the genetic correlation between performance of purebreds and crossbreds (rpc). The rpc is therefore an important parameter for pig and poultry breeders.

Predicting rpc

Estimating the rpc requires measuring performance of crossbred animals, which is costly, and not necessarily done routinely within all breeding programs. The aim of this research was therefore to predict rpc, using only data obtained from purebred animals.

In earlier work, the researchers showed that genetic correlations between populations can be lower than one due to gene-interactions such as dominance and epistasis. Following up on these results, they specifically studied the impact of gene-interactions and genetic differentiation between parental lines on the value of rpc. This resulted in the development of formulas that can predict the rpc based on parental line information only. Using simulations, the researchers showed that these formulas provide accurate upper and lower limits of rpc in several scenarios. Currently, these prediction formulas are being validated in real datasets of pigs.

This research was supported by the Netherlands Organisation of Scientific Research (NWO) and the Breed4Food consortium partners Cobb Europe, CRV, Hendrix Genetics, and Topigs Norsvin.