Zoological Studies

Vol. 37 No. 1, 1998

Effect of Antifreeze Protein on Cold Tolerance in Juvenile Tilapia (Oreochromis mossambicus Peters) and Milkfish (Chanos chanos Forsskal)

Su-Mei Wu1, Pung-Pung Hwang2,*, Choy-Leong Hew3 and Jen-Leih Wu2

1Department of Aquaculture, National Chiayi Institute of Technology, Chiayi, Taiwan 600
2Institute of Zoology, Academia Sinica. Taipei, Taiwan 115
3Departments of Clinical Biochemistry and Biochemistry, University of Toronto, Toronto, Ontario M5G 1L5, Canada

Su-Mei Wu, Pung-Pung Hwang, Choy-Leong Hew and Jen-Leih Wu (1998) The effects of administration of antifreeze protein (AFP) via anal injection, or by feeding, on the mortalities of juvenile tilapia (Oreochromis mossambicus Peters) and milkfish (Chanos chanos Forsskal) exposed to low temperature were examined.
Tilapia juveniles (2.5-3.0 g body weight) were administrated via anal injection 0 (control) or 20 g AFP/ g body weight every 2 d for 6 doses, and later were subjected to cold-tolerance test. The mortality of tilapia, 24 h after the transfer from 26 C to 13 C, was 53.3% in the control and 14.3% in the AFP group. Milkfish juveniles (0.9-1.1 g body weight) were given via anal injection 100 g AFP/g body weight, 100 g BSA/g body weight or saline every 2 d for 6 doses. After injections, milkfish were treated by gradually decreasing temperature within 4-5 d from 26 C to 16 or 13 C. At the end of the experiment the mortality of milkfish was 66.7%-100% in the controls (BSA and saline groups) and 13.3%-33.3% in the AFP group. In the feeding experiment artificial eel feed was given at a level of 0 (control), 100, or 1000 g AFP/g body weight to feed tilapia juveniles (0.01-0.02 g body weight) at a rate of 20% body weight per day for 12 d. The mortality at 24 h after the transfer to 13 C was 60% in the control, 41.9% in the 100 g/g AFP group and 3.4% in the 1000 g/g AFP group.
These results suggest that AFP is able to enhance the tolerance of tilapia and milkfish juveniles to exposure to low temperatures.

Key words: Antifreeze protein, Cold tolerance, Tilapia, Milkfish.

*Correspondence: Tel: 886-2-27899521. Fax: 886-2-27858059. E-mail: zophwang@ccvax.sinica.edu.tw