Effect of Stabilized Fish Oil Source on Sperm Quality and Production of Boars

Abstract

Research findings for supplementing boar stud diets with fish oils are inconsistent. This study was designed to address three possible causes of performance variation of boars to fish oil supplementation: stability of the fatty acid source, level of inclusion and breed of boars tested. Three groups of 87 boars each, from two genetic lines (PIC 337 and PIC 800), were assigned to treatment based on age, mean sperm production (previous 12 weeks), and body condition score. All boars received a corn-soybean meal diet with a commercial fish oil supplement providing 1.83 g/boar/day of docosahexaenoic acid (DHA) as a preconditioning diet. On 10-Aug., 2020, the DHA source was changed to a stabilized starch imbedded source of refined fish oil (Salmate®), providing 1.83 g/b/d for the test diet. Two additional levels providing 2.38 and 2.94 g/b/d of DHA were fed for a 9 week pretreatment period and during the test period. Salmate® fed at 2.38 g/b/d of DHA resulted in a reduction in the number of rejected ejaculates (P 0.045) by 7.5% and 6.4% compared to the lowest and highest inclusion rates, respectively. There were no treatments by genetic line interactions. A retrospective study of semen production and quality of 77 boars on the Salmate® diet containing 1.83 g/b/d DHA was done to compare to the original source of DHA at the same inclusion level. There were no differences in semen quality parameters between the 2 lipid sources. Ejaculate volume increased from 177.9 ml to 233.4 ml (P 0.001) and total sperm cells per ejaculate increased from 69.7 × 109 to 82.0 × 109 (P 0.001) due to substitution of Salmate®. Adding Salmate® at 2.38 g/b/d resulted in a lower number of rejected ejaculates per boar by 7.5% and 6.4% vs. 1.83 and 2.94 g/b/d, respectively, and boars fed Salmate® at 1.83 g/b/d produced 17% more doses than the competing product.