Genetic aspects of female fertility in dairy cattle

The problem area of female fertility in dairy cattle has been discussed, especially as regards its genetic variation and correlation with production, in the light of recently published results. Furthermore, the implications for selection of the parameters found have been illuminated.It is concluded that the magnitude of the additive genetic variance in several fertility traits is considerable, despite the generally low heritability values of individual insemination results. The genetic effect of cow culling within herds for poor fertility is almost negligible, while progeny testing of bulls for daughter fertility offers valuable information for selection purposes.Several recent investigations appear to indicate antagonistic relationships between production and fertility. However, the findings are somewhat ambiguous. When unfavourable, even though not very strong, correlations do exist, detrimental effects on fertility will occur as a consequence of intense long-term selection for yield if the fertility of daughters is not considered simultaneously with production in selection programmes.