During the last two decades, advances in genetic improvement, the area of nutrition and the improvement in the handling of animals, have made production averaged specialized cow’s milk production is increasing; however, such an increase in milk production, has had a negative impact on reproductive performance of these animals, such as low conception rates, which do not correspond to those that were achieved 20 to 30 years ago; so that before they could achieve conception rates 60%, at present and in the best case, only be achieved 40 to 50%. From all this, we can say that today, you can take the 15 to 16% of cows with estrus repetitions problems, which means achieving at least 45% of conceptions.

At present, the problem of repeat breeders, is considered as the second reproductive problems after problems postpartum anestrus, mainly in units bovine production tropics, which is considered as a problem of low fertility, sometimes, is below 30% of pregnancies [1-3].

From the practical point of view, the problems of low fertility, is present when the following symptoms are observed:

- Return to estrus 19 to 23 days after the third service or artificial insemination, without apparent cause.

-Display of normal service intervals.

-No abnormal genital discharge.

-Without the presence of abnormalities in the genital organs, detectable by rectal palpation [2,4].

It is known that fertility problems in animal production units (UPA), are multifactorial disorders among them in oogenesis, degenerated oocytes, disorders of ovulation, fertilization failure, inflammation of the ovaries, disorders of the oviducts, the uterus changes as metritis and endometritis, early embryonic mortality, among others [5-7].
On the other hand, the low fertility of the animals in UPA, is directly related to metabolic disorders, resulting in the high producing cows, usually, may have negative energy balance during the first 70-80 days postpartum.