Estimation of Genetic Parameters for Semen Quality Traits in Large White and Landrace Boars

Artificial insemination is used widely in the swine industry, resulting in increasing focus on the traits of boar semen and methods for their genetic improvement. This study analyzed 21,160 phenotypic records of fresh semen derived from 492 Large White boars and 231 Landrace boars. The semen traits included the semen volume (VOL), sperm concentration (CON), sperm motility (MOT), and abnormal sperm rate (ABN). Single-trait and multi-trait repeatability models were used to assess the overall genetic parameters of semen traits, while random regression models were applied to examine trends in heritability changes over the collection period. In addition, multi-trait repeatability models were also used to estimate genetic and phenotypic correlations among the traits. The single-trait repeatability model indicated heritability estimates of VOL, MOT, CON, and ABN of 0.23, 0.09, 0.22, and 0.07, respectively, for Large White boars, with corresponding values for Landrace boars of 0.42, 0.06, 0.16, and 0.17. The respective values calculated by the multi-trait repeatability model were 0.23, 0.08, 0.22 and 0.09 for Large White boars and 0.43, 0.06, 0.20 and 0.17 for Landrace boars. Sperm motility, sperm concentration, and abnormal sperm rate showed low-to-moderate heritability. Semen volume showed moderate heritability in Large White boars and high heritability in Landrace boars. The random regression results indicated heritability estimates for VOL, MOT, CON, and ABN of 0.24–0.53, 0.05–0.08, 0.13–0.23, and 0.03–0.31, respectively, for Large White boars and 0.08–0.31, 0.02–0.15, 0.26–0.53, and 0.12–0.17 for Landrace boars. Significant negative genetic correlations were found between VOL and CON in both breeds (−0.54 for Large White and −0.73 for Landrace), and between VOL and MOT in Landrace. These findings will facilitate more precise selection to improve boar semen quality and reproductive efficiency in the swine industry.