The present study aimed to compare the quality of chilled stallion semen depending on its
frozen-thawed quality. Semen was collected once weekly for 3 consecutive weeks from 10
fertile Arabian stallions belonging to Al-Zahraa stud, Cairo, Egypt, using a stallion artificial
vagina. Semen was extended with INRA-96 and centrifuged for 10 minutes at 400 ×g. The
sperm pellets were re-suspended to a final sperm concentration of 100 × 106 motile sperm/ml
with INRA-96 either with 5% glycerol and 15% egg yolk (frozen semen) or without (chilled
semen). After cooling to 5 °C, the chilled semen was maintained at 5 °C for 72 hours. The
frozen semen was packed in 0.5 ml straws, equilibrated at 5 °C for 30 min, and placed 4 cm
above the liquid nitrogen level. The chilled and frozen-thawed semen samples were evaluated
for progressive motility, plasma membrane integrity (Hypoosmotic swelling test), acrosome
integrity (Giemsa staining), mitochondrial activity (MTT assay), and DNA integrity (Comet
assay). Depending on the results of frozen-thawed semen, stallions were classified as good and
poor freezers. The results of chilled semen were compared between the good and poor freezer
stallions. The results revealed that the chilled and frozen semen of good freezer stallions
showed higher values of all semen parameters than that of poor freezer stallions (P< 0.01). In
conclusion, the present study revealed that semen from good freezer stallions have higher post-
storage semen quality either after chilling or freezing compared to that of poor freezer stallions. |
