Nutritional Requirements of the Freshwater Prawn Macrobrachium rosenbergii: Comparisons with Species of Penaeid Shrimp

Abstract

The nutritional requirements of the freshwater shrimp Macrobrachium rosenbergii are reviewed and compared with those reported for several species of marine shrimp genus Penaeus. Most of the information has been derived from experiments with juveniles. A comparison of essential amino acid proportions [A/E ratios] between M. rosenbergii and penaeid species suggests only minor, if any, differences in requirements of essential amino acids exist. Qualitative and quantitative fatty acid requirements of the freshwater shrimp are reflective of the lower n-3/n-6 polyunsaturated fatty acid (PUFA) ratio found in the body tissue. In contrast to marine shrimp, both classes of n-6 and n-3 PUFAs with more than 20 carbon atoms [>20C] are equally effective in producing maximum weight gain responses. The dietary requirement for PUFAs appears to be lower than that of penaeid shrimp. Absence of dietary 18°C n-3 or n-6 PUFAs does not affect growth but is associated with a reduction in the weight of the midgut gland expressed as a percent of whole body weight. There is still a level of uncertainty about whether M. rosenbergii requires dietary phospholipid, particularly phosphatidylcholine. A requirement may be age dependent, as suggested for larval and juvenile forms of penaeid species. A combination of dietary phytosterols is equally effective as cholesterol in satisfying a dietary sterol requirement of 0.6% for juvenile M. rosenbergii. Penaeid species require sterols, but dietary phytosterols are not as effective as cholesterol in promoting growth. M. rosenbergii and penaeid shrimp appear to use the same biosynthetic pathway for the production of the carotenoid astaxanthin from dietary (β-carotene and canthaxanthin. The freshwater prawn obtains most, if not all, of its dietary energy requirement from carbohydrates and lipids, thus sparing protein. Protein sparing is maximized when the dietary lipid: carbohydrate ratio is 1:4. Using water-stable sources of dietary vitamin C, a vitamin C requirement for M. rosenbergii has been identified and estimated to be 100 mg/kg. The levels of different ingredients used in the manufacture of diets will ultimately depend on relative digestibilities and nutrient requirements as influenced by the age of the animal and the system used for culture.