Evaluation of different sulfur compounds in the diet of juvenile sunshine bass (Morone chrysops (female) x M. saxatilis (male))
1995
Keembiyehetty, C.N. | Gatlin, D.M. III.
A semipurified basal diet with 35% crude protein, 0.38% methionine and 0.13% cystine was supplemented with different sulfur compounds to evaluate their efficacy in satisfying the total sulfur amino acid requirement of sunshine bass [Morone chrysops (female) X M. saxatilis (male)]. A control diet was supplemented with L-methionine to meet the total sulfur amino acid requirement of sunshine bass, and test diets were supplemented with either DL-methionine, DL-methionine hydroxy analog (MHA), N-acetyl-DL-methionine, taurine or glutathione on an equal-sulfur basis with the control diet. Fingerlings of sunshine bass (mean initial wt +/- SD = 11.3 +/- 0.1 g) were reared in a brackish water recirculating system, and triplicate groups of fish were fed the different diets twice daily. After 8 weeks of feeding, the greatest weight gain as well as best feed and protein utilization values was observed among fish fed diets containing L-methionine, DL-methionine and N-acetyl-DL-methionine. Glutathione and MHA were about 75% as effective in promoting growth compared with L-methionine, while taurine was totally ineffective. Fish fed glutathione had a significantly greater hepatosomatic index (HSI; liver weight X 100/body weight) and lower intraperitoneal fat ratio (IPF ratio; intraperitoneal fat weight X 100/body weight). Plasma methionine level was highest in fish fed DL-methionine. Highest whole-body protein levels were found in fish fed L-methionine N-acetyl-DL-methionine, and DL-methionine, while the lowest level was in fish fed glutathione. Based on these results, DL-methionine and N-acetyl-DL-methionine were most effective relative to L-methionine in satisfying the sulfur amino acid requirement of sunshine bass.
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