The Robertsonian translocation 1/29 (rob(1;29)) is the most worldwide widespread chromosomal abnormality in domestic animals. Previous studies have demonstrated its negative effect on fertility in dairy herds, but not in beef cattle extensively bred. In this study, we analysed the effect of rob(1;29) in a Retinta cattle breed data set gathered during the last 30 years. The data presented herein include rob(1;29) analysis of 11,505 cows from 251 herds, pedigree information of 24,790 animals and 67,457 calving records. Fertility was evaluated using estimated breeding values for the reproductive efficiency (Re), calculated as the percentage ratio between the number of calvings of an individual and the number expected in an optimal situation. Our results showed that cows carrying the heterozygote genotype showed a significant decrease in their Re (−5.10%, p < .001). No decrease was detected in free rob(1;29) animals and homozygous carriers. In addition, the incidence of rob(1;29) in the breed fertility was decreased to very low values after 30 years of avoiding selection of bulls' carrier as stallions. The effect of rob(1;29) on cattle fertility is only significant when the prevalence of carrier individuals is high. Selecting against the disease only by the paternal side reduced the incidence to negligible values.

No 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.

El propósito de este artículo está centrado en hacer algunas reflexiones sobre la calidad y equidad de la educación, como sobre el rendimiento de los alumnos en el aprendizaje de las Ciencias, tomando como base algunos indicadores de estudios internacionales.