Impact of changes in composition of storage medium on lipid content and quality of turkey spermatozoa.

Turkey semen quality is damaged by long term in vitro storage. The objective of the present study was to determine whether changes in energy substrates and antioxidants of semen extender could limit loss of quality and lipid content of turkey spermatozoa during storage. Spermatozoa were incubated in extenders based on Beltsville Poultry Semen Extender (BPSE) to which different energy substrates (acetate, pyruvate and hydroxybutyric acid) or antioxidant (Vitamin E) had been added. Semen was stored at 4°C for 48h and changes in quality, phospholipid and malondialdehyde (MDA) content of semen were evaluated. Among the different substrates studied, only acetate was able to limit the loss of motility and ATP content after 48h in vitro storage. Losses of spermatozoal phospholipids were similar when gametes were incubated in an extender without any substrate or in normal BPSE (784–675nmol/109 spz versus 837–703nmol/109 spz). However, motility and ATP content were significantly more affected after 48h of storage in samples incubated without substrates than in BPSE (motility, 2.2 versus 0; ATP, 10nmol/109 spz versus 3nmol/109 spz). The addition of Vitamin E to the extender did not modify either the MDA or phospholipid content of fresh or stored spermatozoa, but increased the motility of stored semen. In conclusion, acetate is an essential substrate for in vitro storage. Spermatozoal phospholipids decreased during storage, but this did not seem to originate from metabolism of endogenous fatty acids. The positive effects of Vitamin E on semen storage did not originate from preservation of lipid oxidation.