Effect of cryoprotectants on certain seminal attributes and on the fertility of buck spermatozoa

Semen samples were obtained from 12 bucks (3 Beetal, 3 Black Bengal and 6 Beetal x Black Bengal) and 10 different extenders were constituted with varying concentrations of glycerol, DMSO, glycerol + DMSO and glycerol + lactose as the sperm cryoprotective agents. After the collection of semen samples, they were assessed for quality, diluted in different extenders after removal of seminal plasma, packaged in ministraws and frozen after equilibration (5'C) for 5 h. The samples were evaluated immediately after equilibration and again 24 h after freezing for progressive motility, percentage of live spermatozoa and acrosome, head and tail abnormalities. Both motility and the percentage of live spermatozoa were most affected by extenders containing only DMSO and these values improved in glycerol + DMSO extenders as the concentration of glycerol was increased while DMSO was decreased. However, these values were significantly higher in extenders containing glycerol + lactose as the cryoprotective agents, and were found to increase with increased concentration of lactose, being highest in TYGL (180). Acrosomal and tail abnormalities tended to increase between post equilibration and post thawing stage, and were higher in extenders containing the higher levels of DMSO. Significantly (P < 0.01) lower percentages of abnormalities were recorded in the glycerol + lactose extenders. The fertility results showed nonsignificant effect of extenders on the conception rate of does.