Submitted to: Aquaculture Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 2, 1997
Publication Date: N/A
Interpretive Summary: In semi-intensive and intensive shrimp farming, feed cost alone can account for two-thirds of the variable costs. Much of the high cost of feed is due to extensive reliance on marine animal proteins such as fish meal, shrimp meal and squid meal to meet the high protein needs. Less expensive alternative sources of protein need to be identified if shrimp farming industry is to be sustainable. Thus, this study was conducted to evaluate the nutritional values of commercial high-fiber canola meal (CMHF) and low-fiber canola meal (CMLF) in a practical diet for juvenile white-legged shrimp. Each of the test canola products which was used as substitutes for various levels of fish meal, comprised 15, 30 and 45% of the dietary protein. Results of this study showed that CMHF can comprise 30% of the protein in diets of shrimp without significantly depressing growth, feed efficiency, feed intake, protein utilization and survival. However, at this level of CMHF, pellet water stability was lowered and survival of shrimp tended to be reduced. Thus, CMHF probably should not provide more than 15% of the dietary protein for juvenile shrimp. For CMLF, only the diet containing the lowest level of this product supported growth and feed intake of shrimp comparable to those fed the basal diet. The lower nutritive values of canola products relative to that fish meal appeared to be due to poor palatability, decreased pellet water stability and/or presence of antinutritional factors such as glucosinolates, phytic acid and indigestible carbohydrates.
Technical Abstract: This study was undertaken to determine acceptable dietary levels of high fiber canola meal (CMHF) and low fibre canola meal (CMLF) for juvenile shrimp. Four groups of shrimp were each fed one of 7 isnitrogenous and isoenergetic diets to satiation four times daily for 56 days. Each of the test canola products comprised either 15%, 30% or 45% of the protein in a basal diet by replacement of one-third, two-thirds or all of the fish meal protein. Shrimp fed diets in which CMHF and CMLF comprised 45% and 30% of the protein, respectively, exhibited significant reductions in growth and feed intake relative to those fed the basal diet. Feed and protein utilization were not significantly depressed unless menhaden meal in the basal diet was completely replaced by CMHF or CMLF. In general, percent survival and final whole body levels of protein, minerals, and thyroid hormones were not significantly affected by dietary treatment. Water stability of the diet pellets was negatively correlated with their levels of CMHF and CMLF. It is concluded that CMHF can comprise 30% of the dietary protein of juvenile shrimp (Penaeus vannamei) without compromising growth, feed intake, and feed and protein utilization. However, because of a trend towards reduced shrimp survival at this dietary level of canola meal, it is recommended that this protein source not exceed 15% of the protein in practical juvenile shrimp diets. Fibre-reduced canola meal did not have improved nutritive value for shrimp. However, we postulate that one or more fibre-reduced, and solvent-extracted canola protein products may be cost effective substitutes for fish meal protein.