Effects of different dietary n-6/n-3 polyunsaturated fatty acid ratios on boar reproduction

BACKGROUND: N-3 and N-6 polyunsaturated fatty acids are widely used in reproduction, yet few studies have addressed the effects of dietary n-6/n-3 ratios on boar reproduction. The present study aimed to determine the effects of different dietary n-6/n-3 ratios on the reproductive performance ofn breeding boars. Thirty-two boars with body weights of 15.0 ± 1.4 kg were divided into four treatments (C, T1, T2, T3) and fed diets with different n-6/n-3 fatty acid ratios (29.06:1, 20.07:1, 1:1, 1:17.96, respectively) for 174 days. RESULTS: The highest testis index was observed for treatment T2. Sperm density and total sperm number per ejaculate in the T2 treatment were significantly higher than those in all other treatments, whereas the sperm deformity rate was the lowest. Interestingly, the fatty acid compositions and ratios of sperm were consistent with dietary treatments. Acid phosphatase and fructose concentration of seminal plasma, and the total superoxide dismutase and glutathione peroxidase of sperm in T2 were higher than those in other treatments. The concentration of testosterone and prostaglandin E2 increased in boars fed on diets supplemented with fatty acids as compared with boars subjected to the C grouptreatment, reaching a peak at n-6/n-3 fatty acid ratios of 1:1. Furthermore, higher expression of Δ(6)-fatty acid desaturase and peroxisome proliferator activated receptor-α in spermatozoa of the T2 treatment were observed, indicating more vigorous metabolism and intensive hormonal regulation. CONCLUSIONS: Our data suggest that the ideal n-6/n-3 ratio in the diet of breeding boars is 1:1, and proper balancing of n-6/n-3 fatty acids plays an important role in male reproduction.