Lipid and fatty acid profile in neat and collagenase-treated llama sperm

The lipid composition of spermatozoa plasma membranes is crucial for both fertilization and cryopreservation techniques. Llama seminal plasma has unique rheological characteristics and proteolytic enzymes have been used to enhance semen handling. The purpose of this study was to evaluate the plasma membrane lipid composition of llama sperm from neat semen and to compare it with sperm from neat semen incubated with collagenase, as an attempt to determine the possible involvement of collagenase over membrane lipids. Also, we investigate the differences in lipid composition of sperm collected in summer versus winter, and between young and adult animals. Fifty-two ejaculates from six llamas were obtained and routine seminal parameters were evaluated. Cholesterol (Chol), phospholipids (PL), Chol/PL ratio, fatty acid (FA) groups, individual FA, and PL classes were evaluated in sperm from neat semen and after incubation with collagenase. No significant differences were found in Chol, PL, Chol/PL ratio, FA, and PL classes between neat semen spermatozoa and those incubated with collagenase. When comparing these same parameters by season, no significant differences were observed. Younger males showed significantly lower PL content in sperm from neat semen, with a trend of higher Chol, a higher Chol/PL ratio, and lower polyunsaturated FA percentages compared to adult males. In conclusion, this study identified the lipid composition of neat llama spermatozoa, showing that collagenase treatment does not alter it. While no seasonal differences were observed, significant age-related differences in sperm lipid composition were found. The findings provide insights into llama sperm lipids, potentially relevant for cryopreservation.