Influence of supplementing diet with Oleic and Linoleic acid on the freezing ability and sex-sorting parameters of ram semen

In an effort to improve the cryosurvival of both non-sorted and sex-sorted ram spermatozoa the effect of supplementing the ram diet with Oleic and Linoleic acid, in the form of extra virgin olive oil and sunflower oil, respectively, was assessed. Rams (n = 4/group) were fed either (i) a standard maintenance diet (Control), (ii) maintenance diet + 5% (w/w) sunflower oil (Linoleic), or (iii) maintenance diet + 5% (w/w) extra virgin olive oil (Oleic) for a period of 6 weeks. The effect of these diets on the post-thaw (incubated 37 °C, 6 h) motility characteristics (as measured by CASA) of non-sorted, frozen-thawed ram spermatozoa were assessed every 2 weeks. The sex-sorted, frozen–thawed spermatozoa were assessed at the end of the 6 week trial period in the same manner. Linoleic and Oleic diets had a negative impact (P < 0.05) on the total sperm motility, viability and acrosome integrity after a 6 week period of dietary supplementation. Furthermore, the average path velocity and straight line velocity of spermatozoa from Oleic-fed rams was less when compared to samples originating from rams fed linoleic acid or the control diets after both 2 and 6 weeks post-diet modification. Curvilinear velocity of oleic spermatozoa 2 weeks post diet modification were inferior for Oleic—(P < 0.05) compared with Linoleic—but not control-fed rams. Spermatozoa from rams fed Oleic diets exhibited lower (P < 0.05) linearity than spermatozoa from rams fed Linoleic acid (2, 4 and 6 weeks) or the control diets (6 weeks). Diet did not significantly affect any motility characteristic or the viability/acrosome integrity of sex-sorted spermatozoa. Nutritional supplementation with the mono-unsaturated fatty acid, Oleic acid, or the polyunsaturated fatty acid, Linoleic acid, did not improve the cryosurvival of ram spermatozoa — whether or not it had been processed for sex-sorting by flow cytometry. However, these results provide insight into the relationship between nutrition and male reproductive characteristics and further research to elucidate the mechanisms by which diet manipulation affects sperm membranes and subsequent sperm quality is warranted.