Lipid composition of semen in different fowl breeders

The lipid composition of spermatozoa and seminal plasma have been studied in different strains of chicken breeders and in turkey breeders fed a standard commercial diet. The following strains have been considered: egg-type breeders (ISA and RIR), broiler breeders (COBB and ROSS) and NICHOLAS turkey breeders. Semen samples have been collected for lipid analysis during the first half (23-42 weeks) of the reproductive period. The liver and testis tissues have been dissected from RIR, ROSS, COBB and NICHOLAS males at the end of the reproductive period and lipid comoosition determined. The total amount of lipid measured in spermatozoa was higher in turkey (952 μg/109) than in chicken breeders (522 μg/109). Total phospholipid, the main lipid component of spermatozoa, accounted for a lower proportion in turkey (59%) compared to chicken (66-69%) breeders. The relative content of free cholesterol was 20% in spermatozoa of meat-type breeders (chicken and turkey) and 10% in chicken egg-type breeders. In sperm phospholipid, 18:0 was the major saturated fatty acid in all the strains; 18:1n-9 and 20:1n-9 were the major monounsaturates in chicken and turkey strain respectively; 22:4n-6 was the major polyunsaturated fatty acid found in birds and its relative content progressively decreases from ISA breeder (30%) to COBB and ROSS breeders (22%) to NICHOLAS breeders (15%). Phospholipid composition of spermatozoa was similar in all the strains considered: phosphatidylcholine was the main class (34%) followed by a slightly lower proportion of phosphatidylethanolamine; phosphatidylserine and cardiolipin were present in higher proportion in chicken (21-29% and 4.5% respectively) compared to turkey breeders (12% and <1% respectively); the relative content of sphingomyelin was very similar in the different strains (11%). Seminal plasma lipid composition was measured in ISA, COBB and NICHOLAS strains. Phospholipid accounted for 46% and 40% of total lipid in seminal plasma of chicken and turkey breeders respectively; free cholesterol showed the highest (49%) proportion in turkey and the lowest (16%) in chicken breeders; the proportion of free fatty acids was almost seven times higher (34%) in plasma phospholipid of ISA breeders compared to COBB and NICHOLAS breeders. According to the sperm fatty acid phospholipid composition, turkey seminal plasma was enriched in n-9 PUFAs (20:1 and 22:3) compared to chicken. Differences in fatty acid composition of the total phospholipid were found between liver and testis tissue in all the strains studied. The relative content of 18:2n-6 was higher in the liver compared to the testis tissue (20% vs. 3%), 20:4n-6 was present in similar amount in both tissues (11% - 16%), 22:4n-6 was higher in the testis compared to the liver tissue (14% vs. 1%). It is suggested that the most important PUFA 22:4n-6 essential for sperm production is synthesised within the testis tissue and not delivered already formed from the liver tissue.