Effects of diluent type, dilution ratio and preservation period on semen quality in Markhoz goats

This study was conducted to determine the effects of diluent type and dilution rate on chilled-stored and freeze-thawed semen quality in Markhoz goats. Semen from eight young (1.5-year old) Markhoz bucks was collected once a week for eight weeks during November and December by artificial vagina. Ejaculates that had a good quality (mass movement 4 or 5 and sperm concentration 1×109/ml) were pooled and diluted at ratios of 1:2, 1:4, 1:8 and 1:12 with three different diluent: 1- Tris based diluent(Tris), 2- Skim Milk (Milk) and 3-Lactose based diluent. The larger parts of diluted (without glycerol) semen from each treatment were chilled at 5°C and stored for 48 hours. The small other parts of diluted (with glycerol) semen from each treatment were packed into 0.25 ml straws and frozen in nitrogen vapor. Thawing was performed by immersing in water bath at 37°C for 30s. Thawed samples were diluted with the same diluent (but without glycerol) at a ratio of 1:1 and reposed again in water bath at 37°C for 15min. The 0, 12, 24 and 48 h chilled stored and freeze-thawed samples were assessed for percent total motile, progressive motile, live and abnormal sperm. After 0, 12 and 24 h chilled storage, percent total motile, progressive motile and live sperm in Tris 1:2, 1:4, 1:8 , 1:12 were higher than Milk and lactose (p0.05). After 48 h chilled storage, percentage of total motile and live sperm showed a tendency to be high in Tris in comparison with Milk and Lactrose (p0.10), but there was no significant difference between twelve treatments although Tris diluent was more better than Milk and Lactose from the viewpoint of digit. After 0 and 12 h chilled storage, percent abnormal sperm in Milk was higher than Tris and Lactose but there was not significantly different between diluents, likewise after 24 and 48 h chilled storage, percent abnormal sperm was similar in Milk, Tris and Lactose. In freeze-thawed semen samples, there was no significant difference between twelve treatments in all assessed characteristics, but totally Tris diluent was nonsignificantly better than Milk and Lactose. However, freeze-thawed semen qualities in three of diluents at each ratio were very low and undesirable. Conclusion: These results showed that, without seminal plasma removal (sperm washing), diluents at each ratio that tested in current work were not acceptable for freezing Markhoz buck semen, but Tris 1:2,1:4, 1:8 and 1:12 could be useful for chilled storage of liquid semen for 10 h.