The effects of dietary supplementation with docosahexaenoic acid on the phospholipid fatty acid composition of avian spermatozoa.

This study represents an attempt at the dietary manipulation of the fatty acid composition of chicken spermatozoa in order to enhance the levels of n-3 polyunsaturates at the expense of the n-6 fatty acids, which normally predominate in the lipids of avian semen. Male chickens were provided with either a control diet supplemented with maize oil or the test diet supplemented with fish oil (Tuna Orbital Oil) from 10 weeks of age. Semen samples were collected from the birds after 30 and 48 weeks of supplementation. The fish oil diet induced a significant but limited increase in the proportion of 22:6n-3 in the spermatozoan phospholipid in parallel with an equivalent decrease in the proportions of 20:4n-6 and 22:4n-6. However, since the maximal level of 22:6n-3 in the phospholipid that was achieved by fish oil feeding was less than 10% (wt/wt of fatty acids), these changes fell far short of representing a switch from the typical avian pattern to that more characteristic of the n-3 enriched mammalian semen. Analysis of the fatty acid compositions of the constituent classes of phospholipid in the spermatozoa indicated that, in both dietary states, the phosphatidylethanolamine fraction contained much greater proportions of n-6 and n-3 C20-22 polyunsaturates than the phosphatidylcholine fraction. The results indicate that the typical fatty acid profile of the spermatozoa of domesticated poultry, characterised by the predominance of C20-22 n-6 polyunsaturates, displays a considerable degree of resistance to manipulation by dietary means and does not adopt the "mammalian" type of profile following supplementation with n-3 fatty acids.

Effects of dietary supplementation with alpha-linolenic acid on the phospholipid fatty acid composition and quality of spermatozoa in cockerel from 24 to 72 weeks of age.

The aim of this study was to investigate the effects of supplementing the diet of the male chicken with alpha-linolenic acid (18:3n-3) on the phospholipid fatty acid composition, motility and fertilizing ability of chicken spermatozoa. The birds in the control group received a diet supplemented with soybean oil rich in linoleic acid (18:2n-6) whereas those in the test group were supplemented with linseed oil rich in alpha-linolenic acid. A number of age-related changes in the lipid parameters of the spermatozoa were observed in control birds. Between 24 and 72 weeks of age the amount of total lipid in the spermatozoa of control birds increased by approximately 2.4 times and the proportions of cholesterol and free fatty acid also increased significantly, whereas the proportions of phospholipid and triacylglycerol decreased. In addition, the proportion of phosphatidylcholine in the total phospholipid increased, whereas the proportion of phosphatidylserine decreased during the same period. The proportion of docosatetraenoic acid (22:4n-6) in the phospholipid decreased significantly between 24 and 72 weeks of age. The concentration of spermatozoa in the semen of control birds increased to a maximum at week 39 and had decreased significantly by week 72. Supplementation with alpha-linolenic acid had little or no effect on the proportion of docosahexaenoic acid (22:6n-3) in the phospholipid profile of the spermatozoa. However, supplementation with alpha-linolenic acid did produce a significant but small increase in the proportion of docosapentaenoic acid (22:5n-3) recorded at 39 and 54 weeks. Thus, this study shows that the fatty acid composition of the sperm phospholipid demonstrates a marked resistance to dietary manipulation. Supplementation with alpha-linolenic acid significantly enhanced semen fertility at week 39. The results suggest that the small increase in the proportion of n-3 fatty acids in the sperm phospholipids induced by enriching the diet with alpha-linolenic acid is associated with a significant improvement in semen quality at 39 weeks of age.

Lipid and antioxidant changes in semen of broiler fowl from 25 to 60 weeks of age.

Spermatozoa and seminal plasma from cockerels at the beginning and end of their reproductive periods were examined for their lipid composition and associated antioxidant capacities. The significant reduction in concentration of spermatozoa with age was associated with a large increase in lipid concentrations in spermatozoa and in seminal plasma. This change in lipid concentration was accompanied by increases in the proportions of phospholipid and free cholesterol; in contrast, the proportions of these lipid moieties in seminal plasma were reduced. The major phospholipid fractions in the spermatozoa and seminal plasma were phosphatidyl choline and phosphatidyl ethanolamine. There was a large decrease with age in the proportion of phosphatidyl ethanolamine and a commensurate increase in that of phosphatidyl choline in the spermatozoa and seminal plasma. These major changes in phospholipid content were accompanied by a decrease in the amount of phosphatidyl serine in the spermatozoa and increases in phosphatidyl inositol and cardiolipin in both spermatozoa and seminal plasma. The reductions in the proportions of phosphatidyl ethanolamine were accompanied by considerable reductions in the content of the major polyunsaturated fatty acids 20:4 (n-6) and 22:4 (n-6). The changes in lipid composition owing to ageing were associated with a marked reduction within the spermatozoa of the major antioxidant enzyme glutathione peroxidase. The role of these changes in the specific combinations of polyunsaturated lipids and in antioxidant capacity in the reduction in fertility with age are discussed.

Lipid and antioxidant changes in spermatozoa and seminal plasma throughout the reproductive period of bulls.

The lipid compositions and associated antioxidant capacities of spermatozoa and seminal plasma from bulls were examined at the beginning, middle and end of their reproductive period. The reduction in concentration and motility of spermatozoa associated with ageing was accompanied by a large decrease in lipid concentrations within the seminal plasma; this change in lipid concentration was accompanied by an increase in the proportion of phospholipid. By contrast, the proportion of phospholipids in the spermatozoa was significantly reduced. The major phospholipid fractions within both the spermatozoa and seminal plasma were phosphatidyl choline and phosphatidyl ethanolamine. With increasing age there was a large decrease in the proportion of phosphatidyl ethanolamine and a commensurate increase in that of phosphatidyl choline within the spermatozoa and seminal plasma. These major changes in phospholipids were accompanied by a decrease in the amount of phosphatidyl inositol and an increase in that of cardiolipin in both spermatozoa and seminal plasma. The reductions in the proportions of phosphatidyl ethanolamine were accompanied by extensive reductions in the content of the major polyunsaturated fatty acids, arachidonic 20:4 (n-6) and docosahexaenoic 22:6 (n-3); there was a decrease also in the concentration of 22:6 (n-3) in phosphatidyl choline. The changes in lipid composition owing to ageing were associated with a marked reduction within the seminal plasma of the major antioxidant enzyme systems, glutathione peroxidase and superoxide dismutase.

Relationship between spermatozoan lipid composition and fertility during aging of chickens.

Changes in the proportions of the various lipid components in spermatozoa were investigated throughout the reproductive period (24-72 wk of age) of male chickens. Sperm motility and in vivo fertility were also measured, and correlation coefficients with the lipid values were determined. The proportion of total phospholipid (PL) increased to reach a maximum value at 39 wk and decreased significantly thereafter. The relative content of free cholesterol and triacylglycerols showed no change in spermatozoa during aging or in relation to fertility values; free fatty acids and cholesterol esters increased continuously with age. Of the various PL classes, phosphatidylserine and phosphatidylcholine displayed a pattern of changes with age positively and negatively, respectively, in relation to the changes of fertility. The proportion of phosphatidylethanolamine had significantly decreased by the end of the reproductive period. The proportions of C16:0, C18:0, and C18:1n-9 within the PL of the spermatozoa increased with age, and those of C20:4n-6, C22:4n-6, and C22:6n-3 decreased. Positive correlations were found between fertility and total PLs, phosphatidylserine, and PL-bound C20:4n-6 and C22:4n-6; a negative correlation was found between fertility and phosphatidylcholine. Motility was positively correlated with the level of PL and negatively with that of free cholesterol; it was also positively correlated with the levels of C22:4n-6 and C22:6n-3 and negatively with those of C16:0, C18:0, and C18:1n-9. The results suggest that the lipid and fatty acid compositions of spermatozoa may be important predictors of fertility.