Pruebas de identidad y paternidad en ganado Brahman registrado de Costa Rica
Archivos
Fecha
2018
Autores
Campos, Jorge
Camacho, Jorge
Cruz, Argerie
Vargas Leitón, Bernardo
Título de la revista
ISSN de la revista
Título del volumen
Editor
Universidad de Costa Rica
Resumen
En programas de evaluación genética es
indispensable la correcta identificación de los
individuos de la población y la certeza de sus
relaciones de parentesco. El objetivo de este
estudio fue implementar pruebas de identificación y verificación de paternidad mediante 18
marcadores microsatélite en ganado registrado
de raza Brahman de Costa Rica. Inicialmente, se
calcularon parámetros genéticos poblacionales a
partir del análisis de 950 muestras de ADN (7
sementales, 788 vacas y 155 crías) colectadas
durante los años 2015/2016, procedentes de 13
hatos de ganado registrado. Los promedios de
heterocigosidad observada y esperada fueron
de 0,67 y 0,70, respectivamente. El índice de
fijación fue de 4%, con desviaciones significativas del equilibrio Hardy-Weinberg (EHW) en
9 de los 18 loci. Todos los marcadores, excepto
ETH225, presentaron contenido de información
polimórfica mayor a 0,50. La probabilidad de
identidad combinada con todos los marcadores
fue 2,4×10-17 para individuos seleccionados aleatoriamente y 2,6×10-7 para hermanos completos. Las probabilidades de exclusión combinada
fueron superiores a 0,999. Todos estos parámetros presentaron valores satisfactorios para la realización de pruebas de identidad y paternidad.
Seguidamente, se realizaron pruebas de confirmación de paternidad en 137 crías con padre y/o
madre reportados procedentes de 3 hatos. Los
porcentajes de rechazo de paternidad basados
en el principio de exclusión (al menos 2 loci discordantes) vs. índices críticos de verosimilitud,
fueron respectivamente: 18,2% vs. 24,1% para las
madres, 14,0% vs. 12,5% para los padres, y 34,6%
vs. 26,3% para los tríos. Se observaron diferencias significativas entre hatos para el porcentaje
de rechazo de paternidad, oscilando desde 15,6
a 39,4% en madres, 0 a 30% en padres, y 19,5 a
31,8% en tríos. Se demuestra la necesidad de un
mayor control en los apareamientos y en el registro de información genealógica en estos hatos.
In genetic evaluation programs, the correct identification of the individuals of the population and the certainty of their kinship relationships is indispensable. The objective of this study was to implement identity verification and paternity tests using 18 microsatellite markers, in registered Brahman cattle from Costa Rica. Genetic parameters were calculated from the analysis of 950 DNA samples (7 sires, 788 cows and 155 offspring) collected during years 2015/2016, from 13 herds with registered cattle. Average observed and expected heterozygosity were 0.67 and 0.70, respectively. The fixation index was 4%, with significant deviations of the Hardy Weinberg equilibrium in 9 of the 18 loci. All markers except ETH225 had polymorphic information content greater than 0.50. The combined probability of identity with all markers was 2.4×10-17 for randomly selected individuals and 2.6×10-7 for full siblings. The combined probabilities of exclusion were greater than 0.999. All these parameters presented satisfactory values for the accomplishment of tests of identity and paternity. Next, paternity confirmation tests were performed on 137 offspring with reported father and/or mother from 3 herds. Paternity rejection rates based on the exclusion principle (at least 2 discordant loci) vs. critical likelihood values were, respectively: 18.2% vs. 24.1% for mothers, 14.0% vs. 12.5% for fathers, and 34.6% vs. 26.3% for trios. There were significant differences between herds for the percentage of paternity rejection, ranging from 15.6 to 39.4% in mothers, 0 to 30% in fathers, and 19.5 to 31.8% in trios. The need for greater control in mating and recording of genealogical information in these herds is demonstrated.
In genetic evaluation programs, the correct identification of the individuals of the population and the certainty of their kinship relationships is indispensable. The objective of this study was to implement identity verification and paternity tests using 18 microsatellite markers, in registered Brahman cattle from Costa Rica. Genetic parameters were calculated from the analysis of 950 DNA samples (7 sires, 788 cows and 155 offspring) collected during years 2015/2016, from 13 herds with registered cattle. Average observed and expected heterozygosity were 0.67 and 0.70, respectively. The fixation index was 4%, with significant deviations of the Hardy Weinberg equilibrium in 9 of the 18 loci. All markers except ETH225 had polymorphic information content greater than 0.50. The combined probability of identity with all markers was 2.4×10-17 for randomly selected individuals and 2.6×10-7 for full siblings. The combined probabilities of exclusion were greater than 0.999. All these parameters presented satisfactory values for the accomplishment of tests of identity and paternity. Next, paternity confirmation tests were performed on 137 offspring with reported father and/or mother from 3 herds. Paternity rejection rates based on the exclusion principle (at least 2 discordant loci) vs. critical likelihood values were, respectively: 18.2% vs. 24.1% for mothers, 14.0% vs. 12.5% for fathers, and 34.6% vs. 26.3% for trios. There were significant differences between herds for the percentage of paternity rejection, ranging from 15.6 to 39.4% in mothers, 0 to 30% in fathers, and 19.5 to 31.8% in trios. The need for greater control in mating and recording of genealogical information in these herds is demonstrated.
Descripción
Palabras clave
CEBU, GENETICA DE POBLACIONES, COSTA RICA, PRUEBAS DE LABORATORIO, GENÉTICA ANIMAL, POPULATION GENETICS, LABORATORY TESTS