20 Effects of a stabilized fish oil on boar semen quality when fed during summer months

Abstract

Abstract The objective of this study was to investigate the effects of feeding a stabilized fish oil source to different genetic lines on boar semen quality. A total of 127 boars representing three genetic lines (PIC 337, PIC 800, and PIC L03; Hendersonville, TN) at a commercial boar stud were balanced by age, body condition, and previous semen quality and randomly allotted to one of two dietary treatments within genetic line. Boars were assigned to either receive Control; a daily top dress of 32g of corn starch; or Fish oil; a daily top dress of 32g of Salmate DHA+ (The Ballard Group, 2407 Ashland Ave., Cincinnati, OH 45206 USA) to provide 2.38 g of docosahexaenoic acid (DHA). The top-dress supplementation was provided by placing it on top of the daily ration of feed for each individual boar on the floor once each day immediately after their feed has been delivered to them. Supplementation lasted for 16 wk from June-September, 2023 during which weekly semen collection was performed. Semen was evaluated at the stud for concentration and motility parameters using computer assisted semen analysis. Data was analyzed using generalized linear mixed models with the lmer and glmer functions of R. Boar was the experimental unit, with dietary treatment, genetic line, and their interaction tested as fixed effects while age at collection served as a covariate. Boar nested within treatment combinations was used as a random effect to account for repeated measurements within the same boar. There was no evidence (P > 0.10) for dietary treatment by genetic line interaction for any response criteria (Table 1). There was no evidence of fish oil supplementation effects (P > 0.10) on semen volume, concentration, total sperm cells per ejaculate, percentage of accepted ejaculates, or number of doses produced per accepted ejaculate. There was no evidence of fish oil supplementation effects (P > 0.10) on percentage motile sperm cells, or percentage of proximal and distal droplets and abnormal tails. Line 800 boars had the least (P < 0.05) semen volume, but greatest (P < 0.05) sperm concentration, resulting in no evidence for differences (P > 0.10) between the three genetic lines in total sperm cells per ejaculate. Line 03 boars had increased (P < 0.05) percentage of rejected ejaculates as well as decreased number of doses produced per accepted ejaculate (P < 0.05) compared with lines 337 and 800 boars. There was no evidence for differences (P > 0.10) in sperm motility, proximal and distal droplets, or abnormal tails between the three genetic lines. In summary, maternal line boars had an increased proportion of rejected ejaculates per boar and a decreased number of doses produced compared with terminal line boars. Feeding a stabilized fish oil to provide 2.38 g of DHA did not improve semen during summer months.