Estimation of the Genetic Components of (Co)variance and Preliminary Genome-Wide Association Study for Reproductive Efficiency in Retinta Beef Cattle

Abstract

In this study, we analyzed the variation of reproductive efficiency, estimated as the deviation between the optimal and real parity number of females at each stage of the cow’s life, in 12,554 cows belonging to the Retinta Spanish cattle breed, using classical repeatability and random regression models. The results of the analyses using repeatability model and the random regression model suggest that reproductive efficiency is not homogeneous throughout the cow’s life. The h2 estimate for this model was 0.30, while for the random regression model it increased across the parities, from 0.24 at the first calving to 0.51 at calving number 9. Additionally, we performed a preliminary genome-wide association study for this trait in a population of 252 Retinta cows genotyped using the Axiom Bovine Genotyping v3 Array. The results showed 5 SNPs significantly associated with reproductive efficiency, located in two genomic regions (BTA4 and BTA28). The functional analysis revealed the presence of 5 candidate genes located within these regions, which were previously involved in different aspects related to fertility in cattle and mice models. This new information could give us a better understanding of the genetic architecture of reproductive traits in this species, as well as allow us to accurately select more fertile cows.

Genomic Diversity of the Retinta Breed Derived from Two Ancestral Bovine Lineages

“…The Retinta is a breed that has been selected for its rusticity and marked maternal character, and which shows a high reproductive efficiency determined by its genetics [ 29 ]. This is reflected in the inter-generational interval, which was greater in females than in males ( Table 1 ), due firstly to the fact that bulls have a shorter productive life, so they are often used earlier in reproduction than cows, and secondly, that the cows are selected for the next breeding window depending on the year of birth and therefore the animal’s maturity and morphological constitution; otherwise, the breeder will wait for the next one.…”