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The present study was conducted to evaluate the effect of egg yolk concentration and washing on sperm quality in cryopreserved Barbari buck semen at higher dilution (100 × 10 6 cells/ml). Five healthy Barbari bucks of similar age and weight were selected as semen donor. Six ejaculates were collected from each buck during the experiment. Collected semen samples were pooled and diluted with Tris-based semen extender containing 6% glycerol and egg yolk according to the treatments -T-1, that is, 3% egg yolk, T-2, that is, 20% egg yolk and T-3, that is, 20% egg yolk after washing and cryopreserved using the slow freezing technique. Semen was evaluated at three different steps, namely, after dilution, after equilibration and after freeze-thawing. Significantly (p ≤ .01) higher values for motility and viability were observed in T-3 just after dilution while significantly (p ≤ .01) higher values for acrosomal integrity and pattern F (uncapacitated sperm) was observed in T-2. Significantly (p ≤ .01) higher values were observed in T-2 after equilibration and thawing. It may be concluded that incorporation of 20% egg yolk compared to 3% egg yolk or 20% egg yolk after washing in extender confer better cryoprotection to Barbari buck spermatozoa as reflected in semen quality parameters studied. ARTICLE HISTORY

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Earlier we have reported mercury-induced alterations in functional dynamics of buck spermatozoa through free radicals-mediated oxidative stress and spontaneous acrosome reaction. Based on our earlier findings, we aimed to investigate the effect of mercury exposure on motility, kinematic patterns, DNA damage, apoptosis and ultra-structural alterations in goat spermatozoa following in vitro exposure to different concentrations (0.031–1.25 µg/ml) of mercuric chloride for 15 min and 3 h. Following exposure of sperm cells to 0.031 µg/ml of mercuric chloride for 3 h, livability and motility of sperms was significantly reduced along with altered kinematic patterns, significant increase in per cent necrotic sperm cells and number of cells showing DNA damage; and this effect was dose- and time-dependent. Contrary to up-regulation of Bax gene after 3 h in control group, there was significant increase in expression of Bcl-2 in mercury-treated groups. Transmission electron microscopy studies revealed rifts and nicks in plasma and acrosomal membrane, mitochondrial sheath, and collapsed mitochondria with loss of helical organization of mitochondria in the middle piece of spermatozoa. Our findings evidently suggest that mercury induces necrosis instead of apoptosis and targets the membrane, acrosome, mid piece of sperms; and the damage to mitochondria seems to be responsible for alterations in functional and kinematic attributes of spermatozoa.