THE EFFECT OF VARIOUS PROCESSING METHODS ON THE PHYSICAL AND BIOCHEMICAL-PROPERTIES OF SHRIMP HEAD MEALS AND THEIR UTILIZATION BY JUVENILE PENAEUS-MONODON FAB

Three meals were prepared from Penaeus monodon head waste by drying th e raw material in a solar simulator, drying in an oven or blanching th e raw material followed by partial de-watering under pressure and air drying. A further three meals were prepared by passing batches of raw or blanched shrimp head waste through a commercial meat/bone separator . The meat fraction was subsequently dried (MBDD) or ensiled. Separate d meals contained around 6% less ash, 5% less chitin and 7.5% more pro tein than unseparated meals but the procedure failed to remove all the exoskeletal material. Separated meals also contained higher levels of astaxanthin and canthaxanthin than solar or oven-dried meals. The hig hest levels of n-3 polyunsaturated fatty acids (PUFAs) were found in s eparated meals. However, blanching the raw material prior to processin g led to decreased PUFA content, higher free fatty acid levels and sig nificantly higher (P<0.05) peroxide values. All the meals were found t o be deficient in arginine and methionine plus cystine but separated m eals contained greater quantities of the remaining essential amino aci ds and had essential amino acid indices greater than 0.70. Experimenta l rations were prepared incorporating either 54% fish meal or 31% of t he solar-dried, oven-dried or MBDD shrimp head meals plus sufficient f ish meal to generate isoproteinaceous diets. Each diet was fed to trip licate groups of 40, juvenile Penaeus monodon in a 50-day growth trial . Diets containing shrimp head meal performed significantly (P<0.05) b etter in terms of final individual weight, feed conversion ratio and p roduction compared with the 54% fish meal based diet. The diet contain ing separated shrimp head meal produced the best response, followed by the diets containing oven-dried and solar-dried meal, but the differe nces were not statistically significant. Similar trends were noted for specific growth rate (SGR) and survival. Tests on the experimental di ets indicated that the incorporation of shrimp head meals reduced wate r stability but increased diet palatability when compared to the fish meal based diet.