Effect of Including Inbreeding, Heterosis and Recombination Loss in Prediction of Breeding Values for Fertility Traits

Inbreeding results from the mating of related individuals and is becoming increasingly important in domestic livestock populations. Inbreeding depression is the reduction of the mean phenotypic value, particularly for traits connected with reproduction or fitness (Miglior et al., 1992). Inbreeding depression has been shown to decrease milk production by approximately 9-26 kg of milk per lactation for each 1% of inbreeding (Thompson et al., 2000a&b). Research from the US estimated an economic loss in relative net income of approximately £8 per 1% increase in inbreeding over the lifetime of a cow (Smith et al., 1998). Very little data exists for non-production related traits such as fertility, but it is expected that inbreeding depression could be substantially greater for these types of traits than for production traits.