Genetic parameters for various semen production and quality traits and indicators of male and female reproductive performance in Nellore cattle

Abstract

Background Given the economic relevance of fertility and reproductive traits for the beef cattle industry, investigating their genetic background and developing effective breeding strategies are paramount. Considering their late and sex-dependent phenotypic expression, genomic information can contribute to speed up the rates of genetic progress per year. In this context, the main objectives of this study were to estimate variance components and genetic parameters, including heritability and genetic correlations, for fertility, female precocity, and semen production and quality (andrological attributes) traits in Nellore cattle incorporating genomic information. Results The heritability estimates of semen quality traits were low-to-moderate, while moderate-to-high estimates were observed for semen morphological traits. The heritability of semen defects ranged from low (0.04 for minor semen defects) to moderate (0.30 for total semen defects). For seminal aspect (SMN_ASPC) and bull reproductive fitness (BULL_FIT), low (0.19) and high (0.69) heritabilities were observed, respectively. The heritability estimates for female reproductive traits ranged from 0.16 to 0.39 for rebreeding of precocious females (REBA) and probability of pregnancy at 14 months (PP14), respectively. Semen quality traits were highly genetically correlated among themselves. Moderate-to-high genetic correlations were observed between the ability to remain productive in the herd until four years of age (stayability; STAY) and the other reproductive traits, indicating that selection for female reproductive performance will indirectly contribute to increasing fertility rates. High genetic correlations between BULL_FIT and female reproductive traits related to precocity (REBA and PP14) and STAY were observed. The genetic correlations between semen quality and spermatic morphology with female reproductive traits ranged from -0.22 (REBA and scrotal circumference) to 0.48 (REBA and sperm vigor). In addition, the genetic correlations between REBA with semen quality traits ranged from -0.23 to 0.48, and with the spermatic morphology traits it ranged from -0.22 to 0.19. Conclusions All male and female fertility and reproduction traits evaluated are heritable and can be improved through direct genetic or genomic selection. Selection for better sperm quality will positively influence the fertility and precocity of Nellore females. The findings of this study will serve as background information for designing breeding programs for genetically improving semen production and quality and reproductive performance in Nellore cattle.

Genome-wide association study identifies genomic regions associated with key reproductive traits in Korean Hanwoo cows

“…The optimal performance of traits, such as age at first calving, calving interval, gestation length, and number of artificial inseminations per conception, plays a vital role in selective breeding programs, leading to the propagation of desirable genetic characteristics within the Hanwoo population. Their direct impact on productivity, rapid return on investment, and overall sustainability in the Hanwoo cattle industry underscores the economic significance of these traits [ 44 ]. Moreover, a keen understanding of reproductive traits will enable farmers to implement effective farm management practices, ensuring timely breeding and proper adaptation to environmental conditions [ 45 ].…”

Genetic Parameters of Semen Traits and Their Correlations with Conformation Traits in Chinese Holstein Bulls

“…In addition, other conformation traits such as body weight have positive correlations with viable sperm cell production that can also be used for the selection of reproduction traits [ 5 ]. Bulls' breeding fitness may perform superiorly if their morphological conformation is better as well, so bull conformation traits have potential influences on semen production and quality [ 6 ]. Thus, understanding the heritability of these traits is crucial for effective selection programs.…”