Effects of phenotypic data from different time span on pig genetic evaluation

The accuracy and ranking difference of estimated breeding values(EBV) of the same individuals in different time span were evaluated for the major production traits of Duroc pig. Univariate animal model and DMU software were used to estimate the variances and heritabilities of major production traits. The accuracy of EBV and spearman correlation were compared between data from different periods, including two years, three years, four years, five years and all data. The results also showed that the heritabilities of age at 115 kg live weight (AGE), average daily gain between 30-115 kg (ADG), backfat thickness at 115 kg live weight (BF), loin eye area at 115 kg live weight (LEA) and body conformation score (BCS) were 0.22, 0.16, 0.38, 0.30 and 0.08 respectively. Except BCS, the heritabilities of other traits were medium and high. Furthermore, if the variance components were fixed, the accuracy ranges of AGE, ADG, BF, LEA and BCS were 0.62-0.64, 0.56-0.59, 0.72-0.73, 0.67-0.69 and 0.49-0.53 respectively. If the variance components were not fixed and estimated from the specific time span, the accuracy ranges of AGE, ADG, BF, LEA and BCS were 0.64-0.65, 0.51-0.59, 0.61-0.73, 0.67-0.69 and 0.42-0.53 respectively. For another, the spearman correlations were close for conditions of different time span. The results also showed that the prior variance components calculated from the whole data were better than the phase data, while the rank of EBV were close for different periods, so the time span of data could be reduced appropriately.