Polimorfismos del gen BoLA-DRB32* en ganado criollo colombiano / Polymorphism of BoLA-DRB32* gen in creole colombian breeds

Objetivo. Caracterizar el polimorfismo del gen BoLA-DRB3.2* en las razas bovinas criollas y colombianas. Materiales y métodos. En 360 muestras de ADN de ocho razas bovinas criollas (Blanco Orejinegro, Casanareño, Costeño con Cuernos, Chino Santandereano, Caqueteño, Hartón del Valle, Romosinuano y San Martinero), dos razas sintéticas Colombianas (Lucerna y Velásquez) y dos razas foráneas (Brahman y Holstein) se evaluó el polimorfismo del gen BoLA-DRB3.2 mediante técnicas moleculares (PCR-RFLP); se calculó el número promedio de alelos (NPA), las frecuencias, la heterocigocidad esperada (He) y observada (Ho), el equilibrio de Hardy-Weinberg, la estructura genética y los valores de F ST y F IS. Resultados. El NPA fue 14.6 ± 3.8 siendo Caqueteño la raza con mayor NPA (25) y el menor el Chino Santandereano (10). Se encontraron 41 alelos BoLA-DRB3.2* los más frecuentes fueron *28, *37, *24, *23, *20, *27, *8, *16, *39 (0.17, 0.11, 0.10, 0.09, 0.09, 0.07, 0.07 y 0.06 respectivamente). Se encontró alta diversidad genética (He = 0.878) con mayor valor en Caqueteño (0.96) y menor en San Martinero (0.81). Todas las razas se encontraron en equilibrio de Hardy-Weinberg, se encontraron valores altamente significativos de diferenciación genética (F ST= 0.044) y de coeficiente de endogamia (F IS = 0.249). Conclusiones. El ganado criollo colombiano posee alto polimorfismo del gen BoLA-DRB3.2* representado en los altos valores de NPA y diversidad génetica.

Objective. To characterize BoLA-DRB3.2*gen polymorphism in Colombian Creole breeds. Materials and methods. Using 360 DNA samples from eight Creole bovine breeds (Blanco Orejinegro, Casanareño, Costeño con Cuernos, Chino Santandereano, Caqueteño, Hartón del Valle, Romosinuano and San Martinero), two synthetic Colombian breeds (Lucerna and Velásquez) and two introduced breeds (Brahmán and Holstein), polymorphism of BoLA-DRB3.2* was evaluated using molecular techniques (PCR-RFLP). Allele average number (AAN), expected (He) and observed (Ho) allele frequencies, heterozygosity, Hardy-Weinberg equilibrium (HW), genetic structure and F ST and F IS values were estimated. Results. AAN was 14.6 ± 3.8, Caqueteño breed displayed the highest AAN value (25) and Chino Santandereano the lowest (10). 41 alleles of BoLA-DRB3.2* were detected. The most frequent were *28, *37, *24, *23, *20, *27, *8, *16 and *39 (0.17, 0.11, 0.10, 0.09, 0.09, 0.07, 0.07 and 0.06 respectively). High genetic diversity was found (He=0.878) with the highest value for Caqueteño (0.96) and lowest for San Martinero (0.81). All breeds were in HW, and highly significant values of genetic differentiation (F ST=0.044) and inbreeding coefficient (F IS=0.249) were found. Conclusions. The Colombian Creole breeds have a high BoLA-DRB3.2*gen polymorphism represented by the high AAN and genetic diversity values.

Effects of cytoplasmic inheritance on preweaning traits of Hereford cattle

The influence of cytoplasmic inheritance on birth and weaning weight was evaluated in an experimental Hereford herd. Data on 1,720 records for birth and weaning weights from calves born between 1963 and 2002 were studied. Variance components were estimated using MTDFREML procedures and an animal model was fitted for each trait. Direct and maternal additive effects and permanent environment and maternal lineage effects were treated as random, while year and month of birth, age of dam and sex of the calf were treated as fixed. Identification of maternal lineages was based on pedigree information. The contribution to phenotypic variance of cytoplasmic lineages defined by pedigree information was negligible for both traits. Mitochondrial genotypes of cows present in the herd in 2002 were analyzed by single strand conformation polymorphism (SSCP) analysis. Only five different genotypes were identified among 23 maternal lineages. All the animals with records were assigned to maternal genotypes based on pedigree information. The statistical analysis was repeated, removing maternal lineage from the model and including mitochondrial genotype as a fixed effect. No evidence of genotype effects was detected. These results suggest a negligible effect of the mitochondrial genome on the preweaning traits of this Hereford herd.