Comparison of Dormancy at Different Cooling Rates on the Survival of Micropterus salmoides without Water
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Abstract:
In order to study the effect of different cooling rates on the survival of Micropterus salmoides without water, the temperature for temporary culture water (10~13 ℃) was reduced, at a cooling rate of 1, 3 or 5 ℃/h, to the critical temperature (0 ℃) to make the fish go dormant, and the fish was kept alive at 3 ℃ for 12, 14 or 16 hours, respectively. Then, the changes of the blood biochemical indices and muscle quality of Micropterus salmoides were determined during this process, to obtain the optimal cooling rate and improve the survival rate. The results showed that a cooling rate of 3 ℃/h along with the temperature for keep-alive at 3 ℃ was the most effective, and the rate of resuscitation from dormancy and after 16-h keep-alive reached 85.75%, which was significantly higher than those of the other two groups; With the extension of keep-alive time, the contents of cortisol, aspartate aminotransferase, malondialdehyde, urea nitrogen and lactate in the blood of the three cooling-treated groups increased significantly (p<0.05), whilst the contents of Na+/K+-ATPase and serum albumin in the gills decreased significantly (p<0.05). The increases or decreases of the above indices for the group after 16-h keep-alive were 1~2 times those of the control group. Compared with the control, the content of crude protein and the muscular texture indices such as hardness, adhesiveness and chewiness were significantly reduced with the extension of keepalive time (p<0.05). The decreases in the above indices of the 3 ℃/h cooling group were significantly lower than those of the other two experimental groups (p<0.05). In summary, cooling at 3 ℃/h for the keep-alive process had relatively little effect on the liver and kidneys of the fish, which can not only guarantee the survival rate of fish subjected to long distance transport, but also ensure least changes in muscle quality of fish during this process.
