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The fatty acid composition of sperm affects the fertilization rate. The objective was to investigate the effects of dietary fish oil (as a source of n-3 fatty acids) on semen quality and sperm fatty acid composition in sheep. Eight Zandi fat-tailed rams were randomly allocated into two groups and fed either a control diet or a diet supplemented with fish oil. Both diets were isocaloric and isonitrogenous and were fed for 13 weeks, starting in the middle of the breeding season. Semen samples were collected weekly and their characteristics evaluated by standard methods, whereas samples collected at the start and end of the study were assessed (gas chromatography) for sperm lipid composition. Mean (6s.e.m.) sperm concentrations (4.3 3 10 9 6 1.3 3 10 8 v. 3.9 3 10 9 6 1.3 3 10 8 sperm/ml and percentages of motile (77.25 6 3.34 v. 60.8 6 3.34) and progressively motile sperm (74.13 6 1.69 v. 62.69 6 1.69) were significantly higher in the fish oil group than control. Dietary fish oil increased the proportion of docosahexaenoic acid (DHA, C22:6 n-3) in sperm fatty acid composition. We concluded that feeding fish oil as a source of n-3 fatty acids attenuated seasonal declines in semen quality in rams, perhaps through increased DHA in sperm.

The aim of this study was to investigate the effect of adding n-3 fatty acids (FA) and α-tocopherol (VE) to semen extender on freezing ability and FA composition of bull sperm. Semen was collected from 10 Iranian Holstein bulls and was pooled. In the first experiment, semen was divided into 12 groups including 4 levels of n-3 FA (0, 0.1, 1, 10 ng ml(-1) ) and 3 levels of VE (0, 0.1, 0.2 mmol). The treatment of 0.2 mmol VE and 10 ng ml(-1) n-3 FA had the best post-thawed sperm characteristics (P < 0.01). In the second experiment, lipid composition of the latest treatment and control (without FA and VE) was determined. Adding n-3 FA increased docosahexaenoic acid (DHA) percentage before freezing and after thawing. The ratio of n-3 to n-6 before freezing was higher (P < 0.05) in treated group than in control, and this ratio in the fresh sperm was greater than in the post-thawed sperm (P = 0.1). Results suggested that adding DHA accompanied with an antioxidant to an extender could improve cryosurvival of bull sperm via altering membrane lipid composition.

The objective of this study was to examine the interaction of different concentrations of trehalose [0 (T0), 50 (T50) or 100 (T100) mM] and glycerol [5% (G5) or 7% (G7)] on post-thawed quality of ram semen, cryopreserved in a soybean lecithin (SL)-based extender. Twenty-eight ejaculates were collected from four rams and diluted with six trehalose/glycerol combinations: T0G5, T50G5, T100G5, T0G7, T50G7, and T100G7. Sperm motility (CASA), membrane integrity (eosin/nigrosin) and functionality (HOST), abnormal forms, capacitation status (CTC), mitochondrial activity (rhodamine 123), apoptotic features (Annexin V/propidium iodide) and lipoperoxidation (malondialdehyde production) were evaluated after thawing. Extender T100G5 yielded the highest results for total and progressive motility, sperm velocity, normal morphology, functional membranes, active mitochondria and membrane integrity, with P<0.05 in general, except for T50G7 (P>0.05). The combinations T0G5, T0G7 and T100G7 yielded the lowest post-thaw quality. We could not detect significant changes in other kinematic parameters, capacitation status or lipoperoxidation. We conclude that, in our SL-based extender, a combination of 100 mM trehalose and 5% glycerol was the most adequate combination to achieving post-thawing quality in our soybean lecithin-based extender, and our results support that a synergistic effect among trehalose and glycerol exists. We suggest that other combinations could improve these results.