Semen quality of stress negative Piétrain and Duroc boars in the tropics: the case of Vietnam

This study was carried out in Dong Hiep pig farm, North of Vietnam in order to evaluate the semen quality of stress negative Piétrain and Duroc boars. A total of 722 ejaculates from 13 homozygous (CC), 7 heterozygous (CT) stress negative Piétrain and 10 Duroc CC boars was collected between 2008 and 2012. The sperm quality was assessed on each ejaculate using ejaculate volume (VOL), spermatozoa motility (MO), sperm concentration (CO) and total number of spermatozoids (NT). Genetic type of boars, season, year and (season x year) as well
as (genetic type x year) interactions were included in the model as fixed factors. The results show that the semen quality was influenced by all studied effects (p<0.05) except VOL for season (p=0.45) and season x year (p=0.55), and CO for genetic type (p=0.93). VOL and NT (291.74ml and 103.37×109spz) of Piétrain CC were higher than those (241.40ml and 84.58×109spz) of Piétrain CT and (228.05ml and 77.15×109spz) of Duroc (p<0.001) although the values of the 3 genetic groups are in the range of normal semen. MO, CO and NT tend to be higher in cold than in hot season (p<0.001). These results suggest that semen from Piétrain and Duroc boars could be used in tropical climatic conditions (particularly Piétrain CC) and that the semen quality could be improved through reduction of heat stress.