Objective: To evaluate the cryoprotective effect of butylated hydroxytoluene(BHT) on buck frozen semen.
Methods: Semen was collected from Boer(n=6) and Zaraibi (n=6) bucksby electroejaculator for5-weeks. Semen aliquots were diluted at 38 °C in Tris-bufferwithegg yolk 15.0% [vol/vol](TrEY) or soya lecithin2.5% [weight/vol] (TrSL) supplemented with BHT at of 0.0 (Control), 0.5, 1.0, 2.0 and 4.0 mM.Post-thawing motility(at 400X magnification),plasma (Hypo-osmotic swelling test), and acrosome (Trypan blue/Giemsadual staining)membranes, DNA (Comet assay), and lipid peroxidation (by Malondialdehyde concentration) were assessed.
Results: Spermatozoa motility was enhanced by BHTin TrSL extender at 0.5 mM in the2 breeds, and in TrEY extender at 1.0 mM in Boer and at 2.0 mM in Zaraibibucksfor up to 3hrspost-thawing.Plasma and acrosome membranes and DNA integrity of the two breedswere maximally high with BHT at 1.0-2.0 mM in TrEYand at 0.5-1.0mM in TrSL. Lipid peroxidation was minimal with BHT at 1.0-2.0 mMin TrEY and TrSL extenders in the twobreeds. 4.0 mM of BHTdeteriorated spermatozoa motility, and plasma and acrosome membranes.
Conclusions: The consequence of BHTon buck frozen-thawed spermatozoa varied with the levels of supplementation, buck breed, and phospholipid source in the extender. Semen parametersof Boer buck were better in their response to BHT than Zaraibi buck. BHT 1.0 and 2.0 mMin TrEY, and 0.5 mM in TrSLrepresented the best concentrations profitably improved the semen quality of buck semen.