| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 97 === The effects of peanut oilcake as a protein source in diets of hybrid tilapia (Oreochromis niloticus x Oreochromis aureus) were investigated. Eight isonitrous diets were formulated to contain 30% crude protein. The control diet (0% peanut oilcake) containing fishmeal was substituted with peanut cake at 15%, 30%, 45% 60%, 75%, 90% supplemented with lysine and methionine. The basal diet (diet NE90%) was not supplemented with methionine and lysine, but with non-essential amino acids. All-male tilapia fingerlings of mean weight 5.1 ± 0.6 g were stocked at a rate of 15 fish per tank in 28 l glass aquaria and fed 5% body weight twice a day (9 am and 9 pm). At the end of the 10 weeks feeding experiment, significant differences were observed between the fish fed diets with and without peanut oilcake in terms of growth, hematological parameters and ammonia-N excretion. The best weight gain was observed in the control diet but there were no significant differences in the FCR of fish fed diets containing 15% - 75% peanut oilcake. Lowest weight gain was observed in fish fed diet of NE90% (containing 90% peanut oilcake without addition of lysine and methionine). Viscerosomatic and hepatosomatic indices of the control differed significantly from that of fish that were fed other diets at various levels of peanut cake. However, no significant differences were observed among fish fed diets containing peanut cake. Plasma glucose level, total leukocyte count and ammonia-N excretion rates increased directly with peanut oilcake level while, plasma cholesterol level was negatively related with peanut cake level. Diets had no significant effect on plasma protein concentration, intraperitoneal fat deposition and intestinal length ratios. Broken-line analysis (Robbins, 2006) showed break points for substitution of dietary fishmeal with peanut oilcake to be 74.7%, 73.7% and 74.3% based on percentage weight gain, FCR and SGR respectively.
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