多不饱和脂肪酸在雄性反刍动物中的应用研究进展

Advances in the application of polyunsaturated fatty acids in male ruminants

脂肪酸如n-3和n-6多不饱和脂肪酸是重要的营养物质,特别是在冷休克或冷冻保存条件下,通过改变脂肪酸的形态和维持精子膜的完整性来提高雄性动物生殖性能。此外,多不饱和脂肪酸为前列腺素合成提供了前体,可以调节参与前列腺素和类固醇代谢的许多关键酶的表达。针对添加多不饱和脂肪酸的饲料研究表明,多不饱和脂肪酸能在冷冻期间维持精子活力、活性和生育能力,并改善各种动物的睾丸发育和精子形成。除了日粮脂肪酸种类和数量外,多不饱和脂肪酸添加到饲料或添加剂中的方式也非常重要,因为它对雄性反刍动物的精液质量有不同的影响。反刍动物日粮中添加多不饱和脂肪酸的限制是由于瘤胃微生物的生物氢化作用,使不饱和脂肪酸转化为饱和脂肪酸,导致多不饱和脂肪酸数量减少。近年来,许多保护多不饱和脂肪酸免受瘤胃生物氢化的策略得到发展。因此,本文从瘤胃代谢、生物学作用、对生殖的影响以及在雄性反刍动物中的应用策略等4个方面对多不饱和脂肪酸进行综述。

Fatty acids such as n-3 and n-6 polyunsaturated fatty acids are important nutrients,especially in cold shock or cryopreservation,and improve reproductive performance of male animals by changing the morphology of fatty acids and maintaining the integrity of sperm membranes. In addition,polyunsaturated fatty acids provide precursors for prostaglandin synthesis and regulate the expression of many key enzymes involved in prostaglandin and steroid metabolism. Studies on feed supplemented with polyunsaturated fatty acids have shown that polyunsaturated fatty acids maintain sperm motility,activity and fertility during freezing,and improve testicular development and sperm formation in various animals. In addition to the type and quantity of dietary fatty acids,the manner in which polyunsaturated fatty acids are added to feed or additives is also important as it has different effects on the semen quality of male ruminants. The restriction on the addition of polyunsaturated fatty acids in ruminants’ diets is due to the bio-hydrogenation of rumen microorganisms,which converts the unsaturated fatty acids into saturated fatty acids and leads to the decrease of the amount of polyunsaturated fatty acids. In recent years,many strategies for protecting polyunsaturated fatty acids from rumen bio-hydrogenation have been developed. Therefore,this paper reviews the role of polyunsaturated fatty acids in rumen metabolism,biological effects,reproductive effects and application strategies in male ruminants.