Lipid changes in chicken sperm during ageing and alpha-tocopherol dietary supplementation.

Changes in the lipid composition of sperm were investigated during ageing (29, 37 and 48 weeks of age). Cobb broiler breeder males (n=30) were housed in individual battery cages and received a commercial standard diet supplemented with 3 levels of vitamin E (vE): 100 (standard requirement), 200 and 300mg/Kg of feed. Therefore, 3 experimental groups were considered: CO100, CO200, and CO300. Semen samples were routinely collected by abdominal massage, pooled per treatment and diluted. Phospholipid (PL) content and its fatty acid composition (μg/10 cells) were evaluated by GC; α-tocopherol (αT) content was evaluated by HPLC. Data were subjected to Analysis of Variance according to the GLM procedure of SAS considering the age of the breeders, vE level of the diet, and their interaction as sources of variation. PL is the predominant lipid fraction within sperm and its amount significantly increased during ageing. In all experimental groups the major polyunsatured fatty acids (PUFA) of sperm PL were C22:4n-6 and C20:4n-6 and this did not change with ageing. The amount of saturated fatty acids (SFA) significantly increased at 48 weeks of age whereas the n-3/n-6 ratio significantly decreased by age. The average αT content in the plasma membrane of sperm is dependent by the dietary supplementation and significantly increased by age. αT content was 64.78; 90.76 and 188.07 ng/10 cells in the CO100, CO200 and CO300 groups respectively. The increase of the PL content found during age was higher and significant in the CO100 group compared to the increase found in the CO200 and CO300 groups. In all experimental groups, the amount of SFA significantly increased from 37 to 48 weeks of age, whereas the amount of total MUFA, PUFA and the PUFA/SFA ratio were not affected by age. However the final content of SFA at 48 weeks of age was significantly higher in the CO100 compared to the CO300 group. Moreover, αT sperm content significantly increased at 48 weeks in the CO300 group only. This result may be important to decrease susceptibility to peroxidation in sperm by the age. The results confirm an increase of saturation in the sperm plasma membrane during ageing and this effect can be prevented increasing the αT sperm content by dietary manipulation.