Genetic aspects of herd life and conformation traits and their role in genetic improvement programs for dairy cattle are addressed. Based on the nature of relationships between production and herd life, survival ability (involuntary culling) rather than herd life should be included in the breeding goal. The economic value of survival ability is around 40% relative to production. Alternative definitions of recorded herd life traits are discussed, as well as their genetic parameters and properties of associated methods for genetic evaluation. Potential biases in genetic parameters and the associated benefit of adjusting herd life for production are discussed. Methods for recording conformation traits and their genetic parameters and relationships with herd life are reviewed. Finally, incorporation of genetic evaluations for herd life and conformation in selection programs is discussed. It is concluded that direct or indirect (based on conformation traits) genetic evaluations for herd life can aid genetic improvement for overall economic merit. However, genetic evaluations for HL should be considered an intermediate step towards development of selection strategies based on genetic evaluations for fertility traits and resistance to disease.
Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 17. Genetics and breeding of dairy and beef cattle, swine and horses, , 61–68, 1994
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