Reproduction Indicators Related to Litter Size and Reproduction Cycle Length Among Sows of Breeds Considered Maternal and Paternal Components Kept on Medium-Size Farms

SIMPLE SUMMARY: Pig breeds considered maternal components are bred mainly to improve reproductive traits, while those considered paternal components are bred to improve production traits. These two groups of traits are either negatively or weakly positively correlated. For any breed, however, the key factors affecting the profitability of pig production are a properly conducted reproduction process and proper herd management. This research compared reproduction indicators related to litter size (litter size along with the numbers and percentages of piglets born alive, stillborn, and weaned) and reproduction cycle length (the lengths of gestation, lactation, the weaning-to-conception interval, and the farrowing-to-conception interval) among sows of maternal (Polish Large White, Polish Landrace, and Yorkshire) and paternal (Duroc, Hampshire, and Berkshire) breeds. The pigs were raised on three medium-sized farms, of which two were located in Poland and one in the US. The results suggest that Polish Large White and Polish Landrace sows, both considered maternal components, showed much better performance in terms of reproductive indicators than did the other breeds. Sows of all the breeds had short reproductive cycles, an indicator of intensified production, but also of appropriate herd management. ABSTRACT: The present research aimed to study twelve reproductive indicators related to litter size and the farrowing interval for three maternal (Polish Large White, Polish Landrace, and Yorkshire) and three paternal (Duroc, Berkshire, Hampshire) breeds, raised on two farms in Poland and a farm in the United States. The study included 196 sows (45 Polish Large White, 37 Polish Landrace, 26 Berkshire, 33 Duroc, 40 Yorkshire, and 15 Hampshire), which altogether gave birth to 736 litters. The Kruskal-Wallis test was used to verify the influence of the breed on the reproductive traits, with a post-hoc procedure for pairwise comparisons implemented in the pgirmes of R. The adegenet, ade4, and factoextra packages of R were used to conduct multivariate analysis of the traits by means of principal component analysis. The breed significantly (p ≤ 0.05) influenced the following traits related to litter size: the total number of piglets born per litter, the number and percentage of piglets born alive per litter, the percentage of stillborn piglets per litter, the number and percentage of weaned piglets per litter; and those related to the farrowing interval: the lengths of gestation, lactation, the farrowing-to-conception interval, and the farrowing interval. The breed did not statistically significantly influence the number of stillborn piglets per litter and the length of the weaning-to-conception interval. Polish Landrace and Polish Large White sows had the highest numbers of born (for both, the mean of 14.0), born alive (12.9 and 12.7), and weaned piglets (11.5 and 10.5), which statistically significantly differed from these parameters in the other breeds. Polish Landrace sows significantly differed from all the other breeds in terms of the percentage of weaned piglets (84.1%), while Berkshire sows in terms of gestation length (118.4 days).