Fatty acids such as n-3 and n-6 polyunsaturated fatty acids (PUFA) are critical nutrients, used to improve male reproductive performance through modification of fatty acid profile and maintenance of sperm membrane integrity, especially under cold shock or cryopreservation condition. Also, PUFA provide the precursors for prostaglandin synthesis and can modulate the expression patterns of many key enzymes involved in both prostaglandin and steroid metabolism. Many studies carried out on diets supplemented with PUFA have demonstrated their capability to sustain sperm motility, viability and fertility during chilling and freezing as well as improving testis development and spermatogenesis in a variety of livestock species. In addition to the type and quantity of dietary fatty acids, ways of addition of PUFA to diet or semen extender is very crucial as it has different effects on semen quality in male ruminants. Limitation of PUFA added to ruminant ration is due to biohydrogenation by rumen microorganisms, which causes conversion of unsaturated fatty acids to saturated fatty acids, leading to loss of PUFA quantity. Thus, many strategies for protecting PUFA from biohydrogenation in rumen have been developed over the years. This paper reviews four aspects of PUFA in light of previous research including rumen metabolism, biological roles, influence on reproduction, and strategies to use in male ruminants.

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The aim of the study was to evaluate the seasonal variation in fatty acid profile in the milk of different species during summer and winter seasons. Samples were collected in months of summer and winter. Total saturated fatty acids (SFA) content (g/100g of fat) was 13-14% higher in summer than winter in all species. Total monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA) and conjugated linoleic acid (CLA) concentration (g/100g fat) were 10-12%, 3-4%, 30-40% respectively and, higher in winter than summer. MUFA, PUFA and CLA were considerably altered among seasons and species. It was concluded that PUFA and CLA in milk of different species increased during winter season than summer and this may be attributed to the seasonal availability of green fodder.