A decrease in fertility and one has been observed in the last two decades increase in milk production. Decreased fertility is associated with genetic progress, such as improvements in nutrition and management, which has triggered a continuous increase in milk production. This increase in milk production has also been linked to the incidence of double parts, unwanted in dairy cow, as they cause a decrease in livestock profitability and animal longevity and an increase in antibiotic use. One of the most effective strategies to improve the fertility of dairy cows, especially in warm seasons, or to reduce double births and therefore double pregnancies, is embryo transfer. With embryo transfer, the negative effects of lower fertility and increased pregnancy loss would be drastically reduced.
Embryonic transfer would allow the calves and primiparous to be centered the production of daughters of high genetic value for replenishment, and the multiparous in milk production. This would increase the average number of lactations on the farm and the price of the calves sold. Despite all these benefits, this system is not implemented in Spain or in Europe. It would be necessary to make a change of mentality on the part of the farmers and the same veterinarian, in order to make a routine use of this technique in females of more than two parts in commercial dairy farms. This technique could only be implemented on well-managed farms, where other factors that could affect the process, such as nutrition or stress, are controlled.