INDUÇÃO DE PUBERDADE EM NOVILHAS F1 (NELORE X ANGUS) SUBMETIDAS AO PROTOCOLO DE IATF - RELATO DE CASO

Abstract

Given the great demand from the consumer market and exports for beef, livestock farmers and professionals are constantly looking for technologies to improve and accelerate the meat production chain. Genetic improvement and animal reproduction are great allies in the mission to increase the production of quality beef. Of zebu origin, the Nelore breed has late reproductive characteristics when compared to females of taurine origin. For this reason, females of the Nelore breed enter puberty later, and consequently, are older at first birth, which results in a smaller number of calves produced throughout their lifespan. The use of hormones to induce puberty in heifers, when well executed, can have positive responses. Thus, the objective was to evaluate the effect of hormonal induction of puberty in F1 heifers (Nelore/Angus) based on the application of progesterone and estradiol cypionate, and after induction subjected to Fixed Time Artificial Insemination (IATF) protocols on the pregnancy rate at the end of the breeding season. 106 F1 heifers aged between 12 and 14 months were used, induced with the progesterone implant and application of 0.5 mL of estradiol cypionate (ECP) intramuscularly. After 24 days of induction, all females underwent ultrasound evaluation, and females considered pubescent were subjected to the TAI protocol. Of the total of 106 heifers, 87 had the presence of a corpus luteum, that is, 82% became pubescent. At the end of the IATF protocol, of the total of 87 females inseminated, 44 were pregnant at 30 days, resulting in a pregnancy rate of 50.57%. It is concluded that the induction of puberty through the use of progesterone and estradiol cypionate can increase the pregnancy rate in crossbred heifers at the end of the TAI protocol.