New traits to improve the maternal ability of sows under production conditions

Abstract

The aim was to evaluate new traits for better expression of maternal ability in sows and the feasibility of their inclusion as a selection criterion in breeding programs. We used maternity performance records of 4627 Landrace and Large White litters to estimate genetic parameters through the Bayesian approach. Cross-fostering was performed only after piglet individual identification and the high cross-fostering rates were in accordance with the reality of production systems in the country. The group of new traits was made up of measures of average daily weight gain from birth to weaning of fostered and biological litter; average weaning weight of fostered and biological litter; total weight from birth to weaning of fostered and biological litter; and weaning potential of piglets, as the percentage of piglets weaned from the total piglets received at the beginning of the lactation period. The estimated heritabilities for new traits were low (0.02 to 0.06) and consistent with the complexity of the traits indicating maternal ability. The high variation between the correlations verified in this data set warns about the impact of management, mainly from cross-fostering, in the estimates of genetic parameters of complex maternal ability traits. Because of these interactions, there does not seem to be a single, common definition of a maternal ability trait. New litter performance traits attributed to sows, such as average weight gain of litter and average weaning weight, are liable to insertion in breeding programs despite the slow genetic gain and may be the key to improving the sow's maternal ability and potential, reflecting on the quality of the weaned piglet and weight of weaned piglets per sow per year. However, these traits do not replace current litter size traits that must be maintained to mitigate possible negative associations between traits.