The potential for identifying heritable endocrine parameters associated with fertility in post-partum dairy cows

作者：A.O. Darwash, George Lamming, John Arthur Woolliams · 发表于：Animal Science · 年份：1999 · DOI：10.1017/s1357729800050335 · 被引用次数：74 · 研究领域：Reproductive Physiology in Livestock、Genetic and phenotypic traits in livestock、Reproductive Biology and Fertility

Abstract Fertility is an important component of herd production efficiency, as each additional oestrous cycle that does not result in a planned pregnancy adds to the cost of dairy farming. In addition to the negative impact on milk production, the high costs of veterinary intervention, re-insemination and herd replacement, subfertility can affect the rate of genetic gain in traits of economic merit. In contrast with the steady increase in average milk yield per cow during the last 30 years, there has been a decline in conception rate to artificial insemination in both the USA and in the UK. The genetic correlation between yield and fertility has been equivocal. Attempts to improve the reproductive efficiency in dairy cattle through breeding and selection have been frustrated to date by the lack of heritable reproductive parameters conducive to high fertility. However, the traditional fertility parameters of interval to first service, services per conception, days open and calving intervals are highly influenced by managerial decisions and have, as expected, heritabilities too low to permit a meaningful genetic gain through selection. An alternative approach is to use the growing body of evidence that the majority of endocrine factors affecting reproduction are a result of gene expression at the hypothalamic, pituitary, ovarian or uterine level. Mechanisms such as commencement of post-partum cyclicity, follicle wave patterns, manifestation of oestrus, luteal competence and lev...