Statistical Analysis of Stillbirths in Different Genotypes of Sows

Chu, M. X.

doi:2005.18.10.1475

Article

Swine Nutrition and Feed Technology

Asian-Australasian Journal of Animal Sciences 2005;18(10): 1475-1478.
https://doi.org/10.5713/ajas.2005.1475 Published online December 2, 2005.

Statistical Analysis of Stillbirths in Different Genotypes of Sows

M. X. Chu

Abstract

Statistical analysis was conducted on sow stillbirth traits of three genotypes with 2,400 litters including the Erhualian, Large White and the F1 cross of these two breeds. Number of stillborn piglets per litter in the Erhualian, Large White and the F1 averaged 0.85, 0.31 and 0.70, and percentage born alive averaged 95.0%, 97.0% and 95.5%, respectively. Erhualian sows with a greater litter size also had a higher stillbirth rate. Results of analysis of variance indicated that genotype, parity, farrowing year횞farrowing season interaction and total number born had highly significant effects on both number of stillborn piglets per litter and percentage born alive in sows (p<0.0001). Farrowing year had no significant effect on number of stillborn piglets per litter (p>0.05), and highly significant effect on percentage born alive (p<0.01). Farrowing season had highly significant effects on both number of stillborn piglets per litter and percentage born alive (p<0.01). From parity one to parity ten, least squares means for number of stillborn piglets per litter progressively increased with increasing parity and least squares means for percentage born alive progressively decreased with increasing parity. Sows that farrowed in winter had the highest number of stillborn piglets per litter and the lowest percentage born alive, sows that farrowed in autumn had the lowest number of stillborn piglets per litter and the highest percentage born alive. With increasing total number born, least squares means for number of stillborn piglets per litter markedly increased and least squares means for percentage born alive markedly decreased. Results from analysis of paternal half sibs indicated that the heritabilities for number of stillborn piglets per litter and percentage born alive were 0.110 and 0.124, and the genetic, phenotypic and environmental correlations between them were -0.989, -0.951 and -0.948, respectively. These results indicated that number of stillborn piglets per litter and percentage born alive were traits with the similar genetic background.

Keywords: Sow; Stillbirth; Environmental Effect; Genetic Parameter