Braunvieh is an important dual‐purpose breed in the Mexican tropics. The study of its genetic diversity is key to implementing genetic improvement programs. This study was conducted to determine genetic diversity of reproductive traits in a Mexican Braunvieh beef cattle population using single nucleotide polymorphisms in candidate genes. Information from 24 genes with 52 intra‐genic loci reported in literature to be associated with productive life, pregnancy rate and cow and heifer conception rate of 150 Braunvieh males and females was considered. Observed heterozygosity (Ho) revealed high genetic diversity for the studied traits, Ho = 0.42 ± 0.087, relative to that of other populations of the same breed. Cluster analyses were carried out using the Ward and K‐means algorithms. These analyses revealed high genetic diversity that was observed in the biplot of non‐metric multi‐dimensional scaling. It was found that clustering strategy allowed visualisation of distant groups by genotype but not by favourable alleles in all the loci. We found that the genes CSNK1E, DNAH11, DSC2, IBSP and OCLN affected most of the traits in our study and they were highly informative. Therefore, they represent a potential resource for selection and crossbreeding programs of the traits studied in Braunvieh. The analyses showed that the Mexican Braunvieh population has a high level of genetic diversity, arguably due to decades‐long adaptation to the Mexican tropics.
One of the strategies to genetically improve reproductive traits, despite their low inheritability, has been the identification of candidate genes. Therefore, the objective of this study was to detect candidate genes associated with fecundity through the fixation index (FST) and runs of homozygosity (ROH) of selection signatures in Katahdin ewes. Productive and reproductive records from three years were used and the genotypes (OvineSNP50K) of 48 Katahdin ewes. Two groups of ewes were identified to carry out the genetic comparison: with high fecundity (1.3 ± 0.03) and with low fecundity (1.1 ± 0.06). This study shows for the first time evidence of the influence of the CNOT11, GLUD1, GRID1, MAPK8, and CCL28 genes in the fecundity of Katahdin ewes; in addition, new candidate genes were detected for fecundity that were not reported previously in ewes but that were detected for other species: ANK2 (sow), ARHGAP22 (cow and buffalo cow), GHITM (cow), HERC6 (cow), DPF2 (cow), and TRNAC-GCA (buffalo cow, bull). These new candidate genes in ewes seem to have a high expression in reproduction. Therefore, future studies are needed focused on describing the physiological basis of changes in the reproductive behavior influenced by these genes.
En el estudio se compararon umbrales de frecuencia del alelo menor durante el control de calidad de los genotipos, utilizando polimorfismos de nucleótido simple para predecir valores genómicos de características de crecimiento en bovinos Suizo Europeo. El análisis se realizó con 28,973 y 18,994 registros de pesos al nacimiento y destete, 12,835 polimorfismos de nucleótido simple y 300 animales. Las características se analizaron bajo el enfoque de evaluación genómica en un solo paso. Los criterios de comparación fueron: 1) jerarquización de valores genómicos: se estimaron coeficientes de correlación Spearman y Pearson entre valores genómicos predichos con frecuencia estándar del alelo menor (0.05) y niveles menores; 2) habilidad de predicción de los modelos: se realizó validación cruzada con cuatro repeticiones y se obtuvo el promedio de los coeficientes de correlación de los fenotipos reales contra predichos; y 3) coeficiente de regresión simple: los valores genómicos obtenidos con frecuencia del alelo menor estándar e inferiores, fueron las variables independiente y dependiente, respectivamente. El efecto del nivel de frecuencia del alelo menor en la jerarquización de los valores genómicos no fue importante (correlaciones mayores que 0.99, <2.2x10-16). La habilidad predictiva del modelo fue similar: 0.7 promedio. Los coeficientes de regresión fueron cercanos a uno (0.99, <2x10-16). Los resultados sugieren que una frecuencia del alelo menor entre 0.0 y 0.05, no altera las predicciones de valores genómicos en poblaciones pequeñas. Sin embargo, estos resultados son preliminares y susceptibles a cambios si el estudio se repite con un número de marcadores y animales mayor.
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