Diego Moreira de Azeredo

Efeito da sincronização e da indução de estros em novilhas sobre a prenhez e o índice de repetição de crias na segunda estação reprodutiva

This research was aimed at verifying the pregnancy rate in beef heifers submitted to a protocol for estrus induction and synchronization on the parturition period and its effect on the repetition of pregnancy at the second reproductive season. The experimental animals where composed of 194 Hereford and Braford heifers divided in two groups. The treatment group included a protocol of estrus observation and synchronization and fixed-time insemination (FTAI). The control group was submitted to a conventional artificial insemination management, with estrus observation and insemination in the next turn. Both groups were submitted to a natural mating period with clean-up bulls. The heifers were also observed as primiparous on the next reproductive season. The pregnancy rate was 91.7% in the first season for both groups. In the treatment group, 82% of the treated cows calved on the first 40 days of the groups calving season, against 51.7% of the control animals, resulting in a better conception rate in treated heifers (73 vs. 55%) in the second breeding season. The estrus synchronization and FTAI management on the first breeding season of beef heifers produce better pregnancy results also on the second breeding season.