| Co-Investigator(Kenkyū-buntansha) |
IKEDA Itaru Shimonoseki University of Fisheries, Lecture, 水産学部, 講師
MASUMOTO Toshiro Faculty of Agriculture, Kochi University, Assistant, 農学部, 助手 (10238917)
HOSOKAWA Hidetsuyo Faculty of Agriculture, Kochi University, Asoc.Prof., 農学部, 助教授 (40036744)
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| Research Abstract |
In this research, efforts are directed to finding alternative protein sources as substitutes for expensive fish meal and to improving nutrituve values of alternative proteins in practical diet for yellowtail. The search of alternative protein source by feeding experiment and chemical analysis indicated that soybean meal, full-fat soybean meal, corn gluten meal, meat meal and malt protein flour can substitute for fish meal up to 20-30% in yellowtail diet. And, feeding experiment showed that combined dietary addition of these alternative proteins can replace more than half of fish meal without any adverse effects.
The growth retardation was found to depend on amino acid composition, digestibility, and anti-nutrients such as trypsin inhibitor, antigens, and phytate in many plant proteins. Therfore, the elimination of anti-untrients and the improvement of amino acid composition increased the nutritive values of alternative proteins, resulting in high growth rates.
On the development of fish meal-sparing diets, it needs to check the protein content, amino acid composition, anti-nutrients, and digestibility of alternative proteins. Heating, washing and purification lowered the anti-nutrient and antigen contents, and they also increased protein contents of the proteins. Fermentation and hydrolysis effectively ameriorated their protein and carbohydrate digestibilities.
These results suggest that the adequate dietary inclusion of several alternative proteins of good quality maintains a better amino acid balance, resulting in a comparable nutritive value to that of fish meal diet, and that the supplementation of small amounts of amino acid and feeding stimulant, and the amerioration of dietary type can markedly lower fish meal amount in yellowtail diet. Moreover, long term rearing experiments indicate that these fish meal-sparing diets can be practically useful for yellowtail farming.
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