IN-VITRO LIPID-PEROXIDATION OF TURKEY SPERMATOZOA

In vitro spontaneous lipid peroxidation is associated with loss of motility in mammalian spermatozoa and decreased fertility in chicken spermatozoa. The present study determined incubation variables for turkey spermatozoa that affect the rate of malonaldehyde (MAL) production as measured by the thiobarbituric acid assay as an indicator of lipid peroxidation. Pooled turkey semen was diluted 1:2 with diluent, centrifuged, and washed two times with diluent. The effect of spermatozoal concentration on MAL production was assessed by incubating 300-muL aliquots containing 15 X 10(6) to 1,300 x 10(6) washed spermatozoa (equivalent to 50 x 10(6) to 4 x 10(9) spermatozoa per milliliter) for 4 h at 5 C using four diluents: Beltsville Poultry Semen Extender, Beltsville Turkey Semen Extender, .9% NaCl, and phosphate-buffered saline. The concentration of MAL produced per billion spermatozoa was negatively correlated with the spermatozoal concentration of the incubation mixture. Linear regression analysis showed that: log (micrograms MAL per 10(9) spermatozoa) = -.72 [log (number of spermatozoa per milliliter incubated)] + 6.68; r2 = .85. Comparison of two incubation temperatures (5 and 24 C), for two time periods (4 and 24 h), showed that incubation for 24 h at 24 C resulted in the highest MAL production. The other three treatments were similar to each other. When seminal plasma was added to the diluent, MAL production was reduced. These data show that turkey spermatozoa undergo lipid peroxidation, spermatozoal concentration is critical in the development of the MAL assay system, and seminal plasma offers protection against lipid peroxide formation during 24-h storage.