Prise en compte du génotype halothane dans l’évaluation de la population Piétrain.
Résumé
The halothane sensitivity allele (n) is segregating in the French Pietrain breed. Currently, the halothane genotype is used for the choice of young candidates even if it is not included in the genetic evaluation. This study was conducted to determine if the addition of the halothane genotype in the genetic evaluation of the French Pietrain population could improve the accuracy of the estimates of breeding values. Records were available for 47,804 Pietrain pigs of known halothane genotype (6,211 NN, 8,151 Nn, 33,442 nn). Average daily gain, daily feed intake, feed conversion ratio, lean mean content, carcass dressing percentage and meat quality index were recorded on 2,147 females between 2002 and 2008 in the French test stations. Age, backfat thickness and loin depth at 100 kg were recorded on 45,657 pigs in French selection herds during the same period. Two statistical models were compared, one including the halothane genotype as fixed effect (M2) and the other not (M1). Variance components used for predicting breeding values were estimated for the nine traits. Heritability estimates varied from 0.33 to 0.57 for M1 and 0.34 to 0.59 for M2, and were therefore higher than those used in the current genetic evaluation. Breeding values were then estimated using the models M1 or M2. Correlations between M1 and M2 estimates of breeding values were very high for each trait except for carcass dressing percentage, whatever the halothane genotype. According to Kendall correlation coefficients, including the halothane genotype in the genetic evaluation has an impact on the ranking of animals, particularly for the heterozygous ones.
Domaines
Sciences agricoles
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