Studies on the development and nutrition of the caridean prawn Macrobrachium rosenbergii (De Man) (Crustacea: Decapoda)
It is confirmed that Mac brachium match r ii contains much lower w3 HUFA levels than marine prawns. For larvae which have a low HUFA profile at stage I. survival and growth vary in relation to dietary linolenic acid which is the precursor of these long chain fatty acids. Diets containing different levels of w6 fatty acids produced large differences in survival and slight differences in growth. Recently hatched larvae utilize saturated and monounsaturated fatty acids for their energy requirements, as PUFA's increase from stage I to stage II, suggesting that larvae are able to chain elongate. Heavier M. n2ank ii females have heavier clutches and higher numbers of eggs. However, female weight does not influence weight per egg, nor the volume of each egg. The length of incubation does not significantly influence the larval survival though a negative trend is observed. The ratio between the weight of the parent female and the weight per egg (Wegg/W) is found to be 0.036 which reflects a poor fecundity. Recently hatched larvae consume microencapsulated feed, but do not survive beyond day 13. However, artificial diets can be fed successfully from stages VI-VII, the best growth occurring at a feeding rate of 8-16mg of microcapsules per litre. For the caridean M. ma br; zi and penaeid a=LtUa m2nQdgn larvae, edge index increases from 641 and 223, respectively, at the beginning of their development to 1847 and 750 at the end, reaching 2817 and 5000 at postlarval metamorphosis. These results confirm the herbivorous, omnivorous and raptorial feeder classification given by Itoh (1970). Recently hatched M. rosenbargii larvae show poor ability to crush their food and rely heavily on their embryonic lipid droplet reserves. Later, they feed on live diets, such as Artamin and rotifers, containing their own enzymes which aid larval digestion. Between stages V and VII, the cardiac foregut becomes muscular, the pyloric filter apparatus is functional, and the hepatopancreas increases rapidly in size. Residence time of food becomes longer in the foregut, but remains the same, and later decreases, in the midget. Survival and growth on artificial feed coincide with these changes, suggesting that larval enzyme production is sufficient to digest and assimilate such diets.