Estimation of genetic parameters for reproductive traits evaluated by ultrasonography in Senepol heifers

Studies on reproductive tract score (RTS) and antral follicle count (AFC) in Senepol cattle are limited. These traits are essential as they are linked to the reproductive ability and reproductive performance of animals. Understanding the heritability and genetic correlation of these traits is crucial for guiding selection programs and selecting animals with greater reproductive efficiency and higher production potential. Therefore, this study aimed to estimate the genetic parameters of weight, RTS, and AFC in Senepol cattle using transrectal ultrasonography. Reproductive data were collected from 850 female Senepol cattle aged 10-16 months. At the time of evaluation, the following were measured: RTS traits (scores from 1 to 5), AFC (0 to 100), and female weight (kg). The components of (co)variance estimates and genetic parameters were estimated by univariate and bivariate analyses using the bull model. Heritability estimates were moderate for AFC (0.52) and weight (0.46), and low for RTS (0.12). The genetic correlation between RTS and AFC was almost zero (-0.05). The estimated genetic correlation between weight and AFC was -0.41, while the correlation between weight and RTS was 0.48. Selective breeding of AFC and RTS can enhance the reproductive efficiency of the herd and result in animals with earlier pubertal age and increased fertility.