Relationship between body weight and reproductive efficiency in Nelore (bos taurus indicus) heifers submitted to TAI
DOI:
https://doi.org/10.1590/1809-6891v27e-84674EAbstract
The present study aimed to evaluate the influence of body weight and weight change on conception rate and pregnancy loss rates in Nelore heifers subjected to timed artificial insemination (TAI). A total of 1,927 pasture-raised heifers, 24 months-old on average were used. Hormonal protocols were carried out between October 2024 and March 2025. Heifers were weighed at three time points: 50 days before the protocol (D–50), at the beginning of TAI (D0), and at pregnancy diagnosis at 30 days post-AI (PD30). Body weight and average daily gain (ADG) were categorized into quartiles (Q1 = lightest; Q4 = heaviest) and associated with conception and pregnancy loss rates. Statistical analyses were performed using SAS Studio. Initially, a generalized logistic regression model was used, followed by a quartile-categorized model, with a significant level of 5 %. Conception rates of 51.3 % (988/1927) at PD30 and 48.1 % (926/1927) at PD60 were observed. Conception rates were higher (p<0.001) in Heifers with a corpus luteum at the beginning of the protocol. Absolute body weight at D0 was positively associated with conception rates (p < 0.05), as was periconceptional ADG, which influenced both fertility and pregnancy maintenance. Heifers with higher ADG showed a conception rate of 51.3 % (236/460) and a lower pregnancy loss rate of 3.7 % (9/245). Greater body weight performance and the presence of ovarian cyclicity improve conception rates and pregnancy maintenance in Nellore heifers submitted to TAI.
Keywords: ADG; CL; Conception; Pregnancy Loss.
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