56 THE VIABILITY AND LONGEVITY OF OGYE CHICKEN FROZEN SEMEN WITH MITOTEMPOL, MITOCHONDRIA-SPECIFIC ANTIOXIDANT

Abstract

Semen from Korean Native Black roosters (Ogye) was cryopreserved with 8% N-Methylacetamide (MA) in HS-1 diluent, of the following composition (per 100 mL): glucose 0.2 g, trehalose dihydrate 3.8 g, l-glutamic acid monosodium salt 1.2 g, potassium acetate 0.3 g, magnesium acetate tetrahydrate 0.08 g, potassium citrate monohydrate 0.05 g, BES 0.4 g, Bis-Tris 0.4 g, and gentamicin sulfate 0.001 g. Ogye semen was collected 2 times a week by dorsal-abdominal massage and cooled into ice slurry. During dilution, semen was diluted by 2 steps. First, HS-1 diluent that was supplemented with respective concentration of MitoTEMPOL, mitochondria-specific antioxidant was added into fresh semen with same volume. Second, after waiting for 10 min, 16% MA containing diluent was added into first diluted semen so the final concentrations of MA were adjusted to 8%. The concentration of the MitoTEMPOL of first diluent was adjusted to 0.1, 1, 5, and 10 μM. After freezing for 30 min by exposure to liquid nitrogen vapor 4 cm above the surface of liquid nitrogen, the semen was thawed 5°C for 2 min 1 to 3 weeks later. The viability and longevity of thawed Ogye semen were analysed by sperm movement methods. Briefly, 5 μL of thawed semen was placed onto a Makler chamber and the movement of spermatozoa was recorded for 10 s by digital camera and saved as movie files on the computer. With digital rewinding for 1 s of saved movies, the non-motile and motile sperm was counted using a manual counter. The resulting numbers of respective spermatozoa were analysed by Student t-test. The 0.1 and 1 μM treated semen showed significant increases in viability compared with control, 5 μM and 10 μM MitoTempol (77.3 and 84.2% v. 65.4, 53.2, and 21.5%; P < 0.05). The longevity of frozen/thawed Ogye semen for 3 h was also higher in 0.1 and 1 μM treated groups than control, 5 μM, and 10 μM (67.5 and 54.2% v. 36, 5.2, and 1.2%; P < 0.05). With these results, utilisation of mitochondria-specific antioxidant for freezing of Ogye spermatozoa could increase the viability and longevity of frozen-thawed semen. However, treatment with concentrations >1 μM showed negative effects on freezing of Ogye chicken semen. These findings could be helpful for cryobanking of rooster semen for preservation of selected breeders from malignant viral avian disease.