EFFECT OF DIBS WITH DIFFERENT CONCENTRATIONS OF PROGESTERONE IN IATF PROTOCOL FOR LACTATING DAIRY COWS

Abstract

Currently, fixed-time Artificial Insemination (IATF) protocols, in which a variety of hormones are used, facilitate reproductive management in properties. Progesterone (P4) has action in the first stage of the protocol, assisting in the synchronization of growth of a new follicular wave. P4 concentration is dependent on several factors, and has a direct correlation with follicular size. The aim of this study was to evaluate the manifestation of estrus and the conception rate of dairy cows, using concentrations different from P4, according to the amount of uses of intravaginal progesterone devices (BDI) and also to stipulate whether between the animal category and the presence of corpus luteum (LC) at the beginning of the protocol there is influence on the results. We used 88 cows from a dairy property in the state of Paraná, including high and medium-production animals, and primiparous and multiparous animals, submitted to an IATF protocol. The experiment was divided into two stages (experiment 1 and experiment 2), according to the amount of DIB use, and in each step divided into two groups (1A And 2A; 1B E 2B), according to the p4 concentration. As a result in experiment 1, the manifestation of estrus was similar between the groups, group 2A obtained a better conception rate (54.4%), the presence of CL at the beginning of the protocol favored and primiparous women presented higher conception. In experiment 2, there was no difference in estrus manifestation and conception rate between groups (38.09%), the presence of LC also favored conception, but, according to animal category, in group 1B there was no significant difference in conception rate between primiparous and multiparous. In conclusion, it can be observed that higher pregnancy is related to higher concentrations of P4, and that there is reuse of DIBs decreases conception, having a negative result in primiparous. But the effects of different BDI and their concentrations on follicular dynamics within animal categories are not well understood.