Comparison of markers predicting litter size in different pig breeds.

To overcome the limitations of conventional analysis of male fertility in animals and humans, proteomic studies have been performed to develop fertility-related biomarkers for prognosis and diagnosis of male fertility. However, the studies were focused on specific species or breeds. Therefore, a study is required to validate whether fertility-related markers would apply to other breeds in pigs. In this study, previously developed fertility-related biomarkers from Landrace were validated to use for prognosis of male fertility in commercially available breeds. Expression level of eight biomarkers in non-capacitated and capacitated (C) spermatozoa from Yorkshire and Duroc boars was analyzed. And then, to explore the validity of these markers for prognosis of male fertility, i.e. litter size, artificial insemination was performed. Among them, RAB2A (NC) and UQCRC1 (NC) turned out to be highest efficient markers for Yorkshire. RAB2A (C) was most efficient marker for Duroc. Average litter size has increased as much as 1.41 live born after prediction using eight fertility-related biomarkers in Yorkshire. In addition, average 2.52 litter size was increased after prediction using eight fertility-related biomarkers in Duroc. Average litter sizes were especially highly increased after prediction of fertility using RAB2A (NC) in Yorkshire (1.57 piglets) and TPI (NC) in Duroc (3.14 piglets), respectively. As a result, all biomarkers were significantly correlated with litter size. However, overall accuracy to predict litter size in three breeds was different in response with each marker. Average litter size after artificial insemination was also significantly affected by marker selection. Therefore, this study suggests that developed fertility-related markers may be used for prognosis and diagnosis of male fertility irrespective of breed. However, selection of efficient markers for breeds should be considered to obtain more accurate and efficient outcomes.