INDUCTION OF CYCLICITY AND PREGNANCY RATE IN NELORE HEIFERS WITH THE USE OF INJECTABLE PROGESTERONA OR INTRAVAGINAL DEVICE PRIOR TO THE TAI PROTOCOL

Abstract

Efficient reproduction in cattle herds, especially in Nelore heifers, plays a crucial role in the sustainable development of livestock farming. The use of fixed-time artificial insemination (TAI) protocols has emerged as a promising tool to optimize reproductive efficiency. The problem question that guides this research is: Which of the methods, the use of injectable progesterone or intravaginal device, is more effective in inducing cyclicity and improving the pregnancy rate in Nelore heifers submitted to the TAI protocol? In this research, the effectiveness of two hormonal induction methods in Nelore heifers was analyzed, focusing on inducing cyclicity before applying the Fixed Time Artificial Insemination (IATF) protocol. The main objective was to compare the pregnancy rate between two groups of heifers: a group that underwent intravaginal progesterone implantation and another group that received injectable progesterone. The methodology included the random division of heifers into two groups, the application of the respective hormonal treatments and monitoring of pregnancy rates. The results revealed that both methods presented very similar pregnancy rates, with Group 1 (intravaginal implant) reaching a rate of 49.09% and Group 2 (injectable progesterone) recording 47.27%. This small difference suggests that both strategies are effective in inducing cyclicity and can be equally considered to optimize reproductive efficiency in Nelore heifers.