Dietary lysine requirement of freshwater catfish (Mystus numerus)
ความต้องการกรดอะมิโนไลซีนของปลากดเหลือง

Chutima Tantikitti, Asst. Prof., D. of Aquatic Sci., F. of Natural Resources, PSU.
Noppawan Chimsung, D. of Aquatic Sci., F. of Natural Resources, PSU.
Corresponding e-mail : tachutim@ratree.psu.ac.th

Grant : Government of Thailand
Presented : The 9th International Symposium on Nutrition and Feeding in Fish, May 21-25, 2000, Miyazaki, Japan
Key words : lysine requirement, freshwater catfish, diet

A study was conducted to determine the dietary lysine requirement of juvenile yellow mystus fed semipurified diet containing graded levels of lysine. The basal diet contained fish meal, gelatin and crystalline amino acids simulating the amino acid profile of yellow mystus muscle protein except for lysine. Seven experimental diets were formulated to contain lysine at 0.7 (2.00), 1.1 (3.14), 1.5 (4.29), 1.9 (5.43), 2.3 (6.57), 2.7 (7.71), and 3.1 (8.86) % of diet (g/16 gN). Triplicate groups of fish were fed to satiation for 90 days. Specific growth rate, feed conversion efficiency, protein efficiency eratio, productive protein value and daily net protein retention of fish fed diets containing lysine at 0.7% of diet (2.00 g/16 gN) were significantly lower than fish fed diets containing lysine at higher levels. Plasma amonia concentrations were similar in all groups of fish. The digestibility trial between fish fed experimental diet with 2.3% of lysine and diet with fish meal as the sole source of protein showed that digestibility of the experimental diet was significantly higher than the fish meal based diet. Non-linear regression of specific growth rate against dietary lysine levels indicated a requirement of 3.96 g lyine/16 gN.

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