Indução artificial de lactação em bovinos: histórico e evolução

The early culling of dairy cows due to reproductive failure, management problems and other factors that lead the dairy cows to be dried-off without being pregnant, increase costs and decrease profitability of milk production. A possible alternative is the use of artificial lactation induction, a tool that mimics peripartum endocrine profiles with the aim of inducing milk synthesis from the mammary gland. Protocols of induction of lactation in cattle have been studied since the 1940s, and the first studies consisted of hormonal applications for nine months. In the 1970s, there was a significant evolution, when it was established that seven days of steroid hormones application were sufficient to induce lactation. Since then, several protocols using progesterone and estradiol have been tested. Currently, commercial protocols lasts for 21 days and use large volumes of hormones, requiring daily handling of animals. Although current protocols are efficient, enabling good response rate and milk production, so far the degree of discomfort to which animals are exposed is unknown. The purpose of this review is to provide background information on the evolution of protocols, their applications, drawbacks, possible solutions and prospects.