Determinación del efecto del proestro prolongado sobre el tamaño del foliculo dominante y tasa de preñez en bovinos Indicus con Iatf

Abstract

From the reproductive point of view, a herd is efficient if it is able to obtain one calf per year per cow. However, genetic, environmental and management aspects must be considered. In tropical conditions, and specifically in our area, one of the main limitations in bovine milk production is that cattle raising requires maximum efficiency from producers in order to guarantee an economic return. This research project addressed the issue to determine the size of the dominant follicle and pregnancy rate in Indicus cattle by fixed term artificial insemination (FTAI) under the effect of prolonged proestrus. Sixty-one multiparous cyclic crossbred females were selected, with an average weight of 350 to 599 kg with a body condition of 2.79 and when the ultrasound evaluation showed follicles between 8-10 mm. The variables analyzed with descriptive statistics showed a low coefficient of variation, which translates into a group of homogeneous characteristics. However, it should be noted that the left follicle was larger than the right one. On the other hand, tail underpainting assessment showed that most cows expressed estrus. The diagnosis of early gestation did not vary when cows with different seminal doses were compared. In conclusion, in this study, the average follicle size was within the reference values for Indian cows. While the use of sexed semen showed no difference in pregnancy rate in multiparous cows.