Study On Utilization Of Four Plant Protein Sources For Juvenile Cobia, Rachycentron Canadum

In the studies, feeding trials were conducted to evaluate the effect of replacement of fish meal with four plant protein source such as corn gluten meal, wheat gluten meal, cottonseed meal and peanut meal on growth performance, feed utilization and hematological indexes for juvenile cobia (Rachycentron canadum). The results can be briefly summarized as follows:1. An 8-week feeding experiment was conducted to evaluate the potential use of corn gluten meal as a partial replacement of fish meal in the isonitrogenous and isoenergetic diets (approximately 42.5% crude protein, and 8.5% crude lipid) for juvenile cobia with an initial average weight of about 11.5g. Diets were formulated to include 0, 10, 20, 30, 40 and 60% of fish meal protein being substituted by corn gluten meal without methionine and lysine supplementation. The results showed that weight gain rate (WG) decreased significantly when the replacement level of fish meal protein was increased from 20% to 30%, and the 60% diet was the lowest in all groups. These results indicate that up to 20% of fish meal protein can be replaced by corn gluten meal without causing significant reduction in growth. Feed efficiency (FE) and protein efficiency ratio (PER) were significantly affected by the replacement level of fish meal protein being substituted by corn gluten meal, when the replacement level of fish meal protein was 20%, FCR and PER were the highest. Lipid content in liver and muscle increased significantly as the dietary corn gluten meal replacement levels increased. There were significant differences in hematocrit, white blood cell and plasma glucose concentration in fish fed diets with different corn gluten meal replacement levels. Results of this trial indicated that the optimum level of fish meal protein replacement with corn gluten meal, determined by broken-line model analysis was 26.27%, on the basis of maximum weight gain.2. An 8-week feeding experiment was conducted to evaluate the potential use of wheat gluten meal as a partial replacement of fish meal in the isonitrogenous and isoenergetic diets (approximately 42.5% crude protein, and 9.0% crude lipid) for juvenile cobia with an initial average weight of about 10.5g. Diets were formulated to include 0, 10, 20, 30, 40 and 60% of fish meal protein being substituted by wheat gluten meal without methionine and lysine supplementation. The results showed that weight gain rate decreased significantly when the replacement level of fish meal protein was increased from 30 % to 40%, and the 60% diet was the lowest in all groups. These results indicate that up to 30% of fish meal protein can be replaced by wheat gluten meal without causing significant reduction in growth. Feed efficiency (FE) and protein efficiency ratio (PER) showed no significant effect by the replacement level of fish meal protein being substituted by wheat gluten meal. There was a significant increae of lipid content in liver. Moisture and crude protein content were significantly decreased in muscle, while lipid content increased as the dietary wheat gluten meal replacement levels increased. There were significantly decreased tendency in hemoglobin in fish fed diets with increased wheat gluten meal replacement levels. Results of this trial indicated that the optimum level of fish meal protein replacement with wheat gluten meal, determined by broken-line model analysis was 34.05%, on the basis of maximum weight gain.3. An 8-week feeding experiment was conducted to evaluate the potential use of cottonseed meal as a partial replacement of fish meal in the isonitrogenous and isoenergetic diets (approximately 43.5% crude protein, and 8.0% crude lipid) for juvenile cobia with an initial average weight of about 3.16g. Diets were formulated to include 0, 10, 20, 30 and 40% of fish meal protein being substituted by cottonseed meal. Another diet which contained 40% cottonseed meal protein, supplemented with methionine and lysine. The results showed that weight gain rate (WG) decreased significantly when the replacement level of fish meal protein was increased from 10% to 20%, and the 40% diet was the lowest in all groups. These results indicate that up to 10% of fish meal protein can be replaced by cottonseed meal without causing significant reduction in growth. Feed efficiency (FE) and protein efficiency ratio (PER) showed no significant effect by the replacement level of fish meal protein being substituted by cottonseed meal. There were no significant differences in the moisture, lipid, crude protein and ash content in muscle and whole fish as the dietary cottonseed meal replacement levels increased. There were significant differences in totle protein and plasma glucose concentration in fish fed diets with different cottonseed meal replacement levels. Immune assay protocols showed no significant difference. Results of this trial indicated that the optimum level of fish meal protein replacement with cottonseed meal, determined by broken-line model analysis was 5.51 %, on the basis of maximum weight gain.4. An 8-week feeding experiment was conducted to evaluate the potential use of peanut meal as a partial replacement of fish meal in the isonitrogenous and isoenergetic diets (approximately 42.8 % crude protein, and 7.5% crude lipid) for juvenile cobia with an initial average weight of about 3.15g. Diets were formulated to include 0, 10, 20, 30 and 40% of fish meal protein being substituted by peanut meal. Another diet which contained 40% peannut meal protein, supplemented with methionine and lysine. The results showed that weight gain rate (WG) increased significantly when the replacement level of fish meal protein was increased from 0% to 20%, and decreased significantly from 20% to 40%.. These results indicate that up to 20% of fish meal protein can be replaced by peanut meal without causing significant reduction in growth. Feed efficiency (FE) and protein efficiency ratio (PER) were significantly affected by the replacement level of fish meal protein being substituted by peanut meal, when the replacement level of fish meal protein was 20%, both FE and PER were high. There were no significant differences in the moisture, lipid, crude protein and ash content in muscle and whole fish as the dietary peanut meal replacement levels increased. Hematological characteristics showed no significant difference. Immune assay protocols followed a similar trend as weight gain. Superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and glutathione peroxidase (GSH-PX) showed significantly decreased activity when the replacement level of FM protein by PM increased from 20% to 40%. Results of this trial indicated that the optimum level of fish meal protein replacement with corn gluten meal, determined by Quadratic regression analysis was 13.35%, on the basis of maximum weight gain.