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 th e phospholipid fatty acid composition, motility and fertilizing abilit y of chicken spermatozoa. The birds in the control group received a di et supplemented with soybean oil rich in linoleic acid (18:2n-6) where as those in the test, group were supplemented with linseed oil rich in alpha-linolenic acid. A number of age-related changes in the lipid pa rameters of the spermatozoa were observed in control birds. Between 24 and 72 weeks of age the amount of total lipid in the spermatozoa of c ontrol birds increased by approximately 2.4 times and the proportions of cholesterol and free fatty acid also increased significantly, where as the proportions of phospholipid and triacylglycerol decreased. In a ddition, the proportion of phosphatidylcholine in the total phospholip id increased, whereas the proportion of phosphatidylserine decreased d uring 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 bird s increased to a maximum at week 39 and had decreased significantly by week 72. Supplementation with alpha-linolenic acid had little or no e ffect on the proportion of docosahexaenoic acid (22:6n-3) in the phosp holipid profile of the spermatozoa. However, supplementation with alph a-linolenic acid did produce a significant but small increase in the p roportion of docosapentaenoic acid (22:5n-3) recorded at 39 and 54 wee ks. Thus, this study shows that the fatty acid composition of the sper m phospholipid demonstrates a marked resistance to dietary manipulatio n. Supplementation with alpha-linolenic acid significantly enhanced se men fertility at week 39. The results suggest that the small increase in the proportion of n-3 fatty acids in the sperm phospholipids induce d by enriching the diet with alpha-linolenic acid is associated with a significant improvement in semen quality at 39 weeks of age.