<div>Background: Fertility traits in pigs made a restricted progress through traditional selection. Applying marker assisted selection could improve these traits. The aim of the study was to investigate the effects of candidate genes Estrogen Receptor (ESR), Follicle Stimulating Hormone Beta (FSHB) and Prolactin Receptor (PRLR) on sperm quality traits of Landrace and Yorkshire boars under tropical conditions in Northern Vietnam. 
 
Methods: A total of 6306 ejaculates from 140 boars (92 Landrace and 48 Yorkshire) were collected to estimate sperm ejaculate volume (VOL), spermatozoon motility (MO), sperm concentration (CO) and total number of spermatozoon in ejaculate (NT). Ear tissue samples were collected for genotype identification of SNP present in ESR, FSHB and PRLR genes using PCR-RFLP technique. A mixed model was used to test the effect of different genetic and non-genetic factors on the sperm quality traits. 
 
Result: The genotype frequencies of ESR, FSHB and PRLR were in Hardy-Weinberg equilibrium for each breed. Age of boars and month of the year had significant effect on all the sperm quality traits (P&lt;0.01) while effect of breed was found to be non-significant on all the sperm quality trait. FSHB gene significantly (P&lt;0.05) affected VOL, MO and CO. Boars with BB genotype showed positive effect on VOL but negative effect on MO and CO in comparison with AA genotype boars. ESR gene showed only effect on VOL while PRLR affected only MO. Boars with AA and AB genotypes of ESR gene had a significantly higher VOL than those with BB genotype (P&lt;0.05). For PRLR gen, AB genotype was associated with higher MO than AA genotype (P&lt;0.05). These results suggest a possibility of using the existing polymorphisms in ESR, FSHB and PRLR genes to improve some sperm traits of Landrace and Yorkshire boars.</div>

<div>Effect of ESR, FSHB and PRLR Genes on Sperm Traits of Landrace and Yorkshire Boars in the Tropical Environmental Conditions of Vietnam</div>