Raising Prawns For Beginners
                     Raising Prawns
The farming of the giant freshwater prawn
Macro brachium rosenbergii popularly known as 'scampi' has-been expanding in India recent years. 
Scampi farming gained momentum after the set-back in shrimp farming due to disease outbreaks 
and other factors. 
The infrastructure available to produce shrimp seed and process the shrimp was helpful in providing 
support to scampi farming. The existing culture system includes both monoculture and polyculture 
with Indian major carps in ponds. Grow out stocking densities range from0.5-2.5 scampi per m2 in 
polyculture and 1-5 per m2 in monoculture. The culture period is 6-8 months starting at the 
beginning of southwest monsoon (June-July, 27-30°C ). The scampi are fed with farm-made or 
commercial feeds. This article summarizes the nutrition and feeding of freshwater prawns (grow 
out), with special reference to culture conditions in India.
Nutrient Requirements
There is a fairly good amount of information on the nutrient requirements of freshwater prawn. The 
prawns are capable of digesting a wide range of foods of both plant and animal origin. 
Characterization of the activities of the digestive enzymes in the alimentary tract indicates the 
presence of enzymes like try sin, amino peptidases, proteases, amylases, chitinase, cellulase, 
esterases and lipases. Nutrient requirements of different grow out stages of prawn are summarized 
in Table 1.
Proteins and Amino Acids:
Diets with about 35-40% protein and gross energy level of about 3.2 kcal/g diet and protein: energy 
ratio of about125-130 mg protein/kcal are suitable for growth of M.rosenbergii in clear water 
systems that do not have any supply of natural foods. Broodstock reared in ponds having natural 
food (benthic micro- and macro fauna) require about 30%protein in the diet. Many commercial 
feeds for grow-out contain 24-32% crude protein. Protein/starch ratio of 1:1 is known to be 
effective for better feed efficiency and growth rate.
The prawn requires the same ten essential amino acids as other crustacean and fish species, but 
quantitative requirements have not been determined. The amino acid composition of the prawn 
muscle is used to provide guidance values in feed formulation.
Carbohydrates:
The comparatively high specific activity of amylase found for M. rosenbergii supports the fact that 
the species efficiently utilizes carbohydrates as a source of energy. During fasting, energy 
metabolism in the prawn is dominated by carbohydrates, followed by lipids and proteins. Complex 
polysaccharides including starch and dextrin are more effectively utilized than simple sugars. 
Dietary glucosamine (an amino sugar and intermediary between glucose and chitin) facilitates 
molting followed by enhanced growth. Dietary protein is efficiently utilized at dietary lipid-
carbohydrate ratio of 1:3-1:4. The prawns are also known to utilize as high as 30%dietary fiber.
Lipids and Fatty Acids:
In freshwater prawn that uses dietary carbohydrate efficiently as energy source, protein sparing by 
lipids is not considered to be crucial. The dietary lipid level in prawn diets can be as low as 5 % 
provided the lipid source contains sufficient levels of essential fatty acids. 
There is a dietary requirement for highly unsaturated fatty acids (HUFA) although in very small 
quantities. Both n-3 and n-6 HUFAs at dietary levels of 0.075% are known to increase weight gain 
and feed efficiency remarkably. In addition both 18:2n-6 and18:3n-3 are also required.
M. Rosenbergii, like other crustaceans, is unable to synthesize cholesterol due to the absence of the 
enzyme 3hydroxy 3 methylglutaryl CoA reductase. The dietary requirement for cholesterol is 
approximately 0.3-0.6% in diet.
Substitution with 0.6% ergosterol or stigmesterol is generally not so effective compared to 0.6% 
cholesterol. However, a mixture of phytosterols (sitosterol, campesterol and dihydrobrassi-casterol) 
has been found to be as effective as cholesterol. So, unlike in penaeid shrimp feeds, there is no need 
to add high levels of purified cholesterol in freshwater prawn feeds provided the ingredients contain 
sufficient levels of phytosterols.
Low level of dietary cholesterol in brood stock diet is known to adversely affect egg quality 
resulting in inferior quality of seed production The cholesterol content in the eggs and hepato 
pancreas, and total lipid content in the ovary and hepatopancreas of pond reared brood stock fed 
with a diet containing 30% crude protein and 5% lipid was significantly lower when compared to 
the eggs from wild brood stock collected from the lower reaches of the river Brahmin in Orissa, 
India. Higher levels of lipids and cholesterol are probably key factors in egg maturation and egg 
quality.
The freshwater prawn also has limited ability to biosynthesize phospholipid (PL) de novo. A basal 
level of 0.8%dietary PLs is required to meet the demand of the scampi brood stock. A dietary source 
of phosphatidylcholine (PC) in the form of soy-lecithin is essential for larval growth and survival. 
Supplementation of larval diets with 5% soy-lecithinalong with 1 % cod liver oil and 1% groundnut 
oil improved growth rate by164%. In the absence of sufficient levels of bile salts during 
development, dietary PC may also enhance the assimilation of ingested fats by acting as temporary 
emulsifier.
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