Proceedings of the World Congress on Genetics Applied to Livestock Production, 11.565 Records on group of individuals rather than on individuals could be valuable for predicting breeding values (BV) for the traits which are difficult or costly to measure individually, such like feed intake in pigs. The objectives of this study are to demonstrate the feature of variance components of group records and the model for predicting BV, and investigate efficiency of group records for predicting BV in various situations with regard to size and structure of group and the effects affecting the trait. The data were simulated by mimicking feed intake in pigs where the pooled records of a pen were taken as a group record. The trait had a heritability of 0.3, and variances of both litter effect and pen effect in proportion of phenotypic variance were 0.1 or null. In each generation, 30 sires mated 600 sows, and each sow had one litter with six pigs available. The models ignoring litter and pen effects had a very little or no influence on accuracy of EBV obtained from group records. However, ignoring litter effect caused a biased estimate of additive genetic variance and EBV. The existence of litter and pen effects reduced accuracy of EBV even though the prediction model fitted the two effects. More littermates in the same pen led to higher accuracy of EBV. The decay of EBV accuracy with increasing group size was more profound for scenarios with litter and pen effects on the trait than that without the two effects. In the scenario where a litter of six individuals were divided into two pens, accuracies of EBV obtained from group records with size up to 15 (average 12) and up to 30 (average 24) were 73.2% and 63.6% of those estimated from individual records in the case of no litter and pen effects, but 63.4% and 46.6% in the case having litter and pen effects. The results indicate that using group records for genetic evaluation of the traits such as feed intake in pig is feasible, and the efficiency depends on size and structure of group as well as the magnitude of litter and pen variances. Keywords: group record, variance components, breeding value, accuracy.

Guosheng Su, Per Madsen, Bjarne Nielsen, Tage Ostersen, Mahmoud Shirali, Just Jensen, Ole Christensen

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Methods and Tools - Prediction 3, , 565, 2018
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