| The sunshine bass has become a popular food and sport fish in the United States. Development of an artificial diet specifically for this fish is needed to improve its production efficiency in aquaculture.; A series of studies was conducted to establish dietary requirements of sunshine bass for lysine, threonine and total sulfur amino acids. Semipurified diets containing 35% crude protein from fish muscle and crystalline amino acids were used. Basal diets were supplemented with graded levels of either lysine, threonine or methionine and fed to juvenile fish in triplicate aquaria for 8 or 9 weeks. Weight gain responses indicated requirements for lysine, threonine and total sulfur amino acids of 4.0, 2.8 and 2.9% of dietary protein. The sulfur amino acid requirement appeared to be most critical, and bilateral cataracts were observed in methionine-deficient fish.; Another study was conducted to evaluate different sulfur compounds as methionine supplements in semipurified and soybean-meal-based diets. Dietary DL-methionine and N-acetyl-DL-methionine supported weight gain similar to L-methionine while dietary glutathione and DL-methionine hydroxy analog (MHA) were less efficacious. Weight gain of fish fed a diet with 100% protein from fish meal was comparable to that of fish fed soybean-meal-based diets (75% protein from soybean meal, 25% protein from fish meal) fortified with either L-methionine, DL-methionine or N-acetyl-DL-methionine. However, fish fed soybean-meal-based diets without methionine supplementation or with MHA had reduced weight gain.; Another study was conducted to determine organic matter and protein digestibility of some practical feed ingredients for sunshine bass. Three different fish meal sources (low temperature processed menhaden fish meal, regular menhaden fish meal and anchovy meal), poultry by-product meal, meat and bone meal, soybean meal and cottonseed meal were evaluated. Protein digestibility of animal and plant feedstuffs was similar while organic matter digestibility was generally greater for the animal feedstuffs.; Diets for sunshine bass should be formulated to supply, as a percent of protein, at least 4.0, 2.8 and 2.9% of lysine, threonine and total sulfur amino acids. Diets containing predominantly plant feedstuffs will likely require methionine supplementation as DL-methionine.* ftn*Originally published in DAI Vol. 56, No. 10. Reprinted here with corrected title. |
