Shrimp require the same 10 essential amino acids as do finfish and ter- restrial animals. Arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine have been found to be essential forPenaeus japonicus, P. azteus, Palaemon serratus, andP. monodon.
However, the quantitative requirements for all of the essential amino acids have not been determined. In the absence of information on quantitative amino acid requirements, the essential amino acid profile of the protein in an animal can be used. Table 13.9 lists the essential amino acid contents ofP. japonicus andP. vannameimuscle and, also, of squid, which is a high- quality protein for shrimp. A shrimp diet with an essential amino acid profile similar to that of shrimp muscle, clam, or squid would likely provide good growth in the fed shrimp.
Table 13.9
Essential Amino Acid Content of Proteins from Shrimp Muscle (Penaeus japonicusand P. vannamei) Clam, Squid, and Whole Egga
Protein source (%)
Amino acid P. japonicusb P. vannamei Clamb Squid Casein Whole eggb
Arginine 7.46 8.54 4.50 5.40 3.30 5.45
Histidine 1.66 1.86 1.27 1.50 2.65 1.71
Isoleucine 2.89 3.40 2.00 2.88 4.50 3.46
Leucine 7.04 6.28 4.01 5.79 8.76 6.47
Lysine 7.24 6.97 4.68 5.52 7.34 5.45
Methionine 2.92 2.48 1.70 2.30 2.51 3.01
Phenylalanine 3.90 3.39 2.13 2.86 4.75 4.15
Threonine 3.62 2.69 2.81 3.28 3.77 3.73
Tryptophan 0.52 1.27 0.51 0.72 1.21 3.76
Valine 2.87 3.38 2.18 2.66 5.83 3.76
aAdapted from Lovell (1989).
bFrom Deshimaru (1982).
The optimum dietary protein level for growth of penaeid shrimp has been reported to range from 28 to 60%. These values differ due to species, size, protein quality, level of nonprotein energy, physical quality of pellet, palatability of diet, feeding rate, water quality, and availability of natural food organisms. Most of the quantitative protein requirements were determined with small shrimp in tanks or aquaria in the absence of natural aquatic foods.
Shrimp grown to harvestable size in ponds likely require less protein in their feed than the higher values reported in the literature.
The protein percentage in commercial feeds fed in intensive culture sys- tems is usually 35% or higher. That in semiintensive culture feeds varies, generally from 25 to 35%. Research at the Enrique Ensenot Marine Lab- oratory in Panama showed that 25% protein feeds were as productive as higher-protein feeds in fertilized semiintensive culture ponds containing five shrimp per square meter. Similar results were obtained in a cooperative study between Auburn University and Granjas Marinas Farm in Honduras.
Numerous studies have been conducted to evaluate the nutritional values of various protein sources. Fish meal is a high-quality source for finfish but seems to have a lower nutritional value for shrimp, especially when fed as the sole protein source. This has been reported for several species. Shigueno (1975) has suggested that this may be due to a shortage of phenylalanine and the basic amino acids (arginine, histidine, and lysine) in some fish meals.
An important role of fish meal in shrimp feeds is to enhance palatability.
Soybean meal, the most commonly used plant protein in feeds for warm- water fish, has been found to be a relatively good protein source for shrimp.
It provided better growth ofP. duorarumthan fish meal, shrimp meal, casein, or corn gluten meal (Sick and Andrews, 1973). Soybean meal at levels of 20 to 50% of the diet has been suggested as a replacement for much of the fish meal, shrimp meal, squid meal, or their combination in practical diets for shrimp. Lim and Dominy (1990), however, suggested that, if pellet palatability and water stability can be maintained, the level of soybean meal in the diets of juvenileP. vannameican be increased up to 56%.
Cottonseed meal has been shown to be relatively palatable to shrimp.
However, cottonseed meal (0.41% free gossypol) should not be included at more than 26%, or 1100 ppm of free gossypol, in diets of juvenileP. vannamie.
Also, cottonseed meal is very low in lysine and, for this reason, is not an equal substitute for soybean meal.
Attempts to supplement amino acid-deficient diets with crystalline amino acids have not been successful with shrimp, in contrast to results with chan- nel catfish and farm animals. Deshimaru (1982) showed that the rate of incorporation of free radioactive arginine into muscle protein was less than 1%, compared to the incorporation of 90% of protein-bound arginine. Mai et al.(1988) showed that juvenileP. orientalisdid not absorb free methionine and lysine simultaneously with the protein-bound amino acids. The inability of shrimp to utilize free amino acids as substitutes for protein-bound amino acids is probably due in part to differences in the rate of absorption of free and protein-bound amino acids.
Providing the optimum amount of energy in the diet is important be- cause a deficiency in nonprotein energy means that part of the protein will be used for energy. Inclusion of an appropriate amount of carbohydrates and lipids in the diets of several shrimp species lowered the protein requirement without reducing the growth performance. Excess energy in the diet, how- ever, can limit feed consumption, thereby reducing the intake of protein and other nutrients. Sedgwick (1979) found that the amount of feed consumed byP. merguiensisis regulated by the dietary energy level irrespective of the protein content. Relatively little is known about the energy requirements of shrimp. However, the optimum energy-to-protein ratio for of shrimp seems to be similar to that of finfish, 9–11 kcal/g protein. SmallP. merguiensishad maximum growth with a 39.5% protein diet having a gross energy value of 4.42 kcal/g (Sedwick, 1979). The crude protein-to-gross energy ratio in this study was approximately 90 mg/kcal or 11 kg/g. A practical diet made with conventional ingredients and containing 25 to 35% protein and 4 to 5% fat would have a favorable energy-to-protein ratio.
Shrimp appear to utilize carbohydrates and lipids as dietary energy sources to spare protein. They utilize protein well as an energy source, however, studies have shown that diets with too high a ratio of protein-to-nonprotein
energy depress the growth rate. Lipids are required in the diets of shrimp not only for their caloric value but also as sources of essential fatty acids, fat-soluble vitamins, sterols, and phospholipids necessary for normal growth.
Feeding experiments have shown that linoleic (n-6)- and linolenic (n-3)- series fatty acids are dietary essentials forP. japonicus, P. indicus, Palaemon serratus, P. stylirostris,andP. vannamei.Shrimp appear to have a limited ability to desaturate and elongate 18 : 3n-3 to 20 : 5 n-3 and 22 : 6n-3 fatty acids, which are the biologically active fatty acids. The optimum dietary level of highly unsaturated n-3 fatty acids, 20 : 5 n-3 and 22 : 6n-3, for shrimp has been determined to range from 0.5 to 1.0%, while the optimum level of the n-6 series of fatty acids is estimated to be approximately 0.5%. Diets containing 0.5%n-6 and 0.5%n-3 fatty acids have provided for maximum growth of several shrimp species.
Although dietary lipids have a sparing effect on the utilization of protein, shrimp do not tolerate as high a dietary lipid level as do salmonid fish. Several studies using different lipid sources or combinations have suggested that a lipid level in excess of 10% tends to depress growth.
Crustaceans do not synthesize sterols from acetate or mevalonate as do finfish, and therefore they require a dietary source. Cholesterol is the major sterol found in crustaceans and is a precursor of sex hormones, molting hormones, and a constituent of the hypodermis in crustaceans. In addition to the essential fatty acids and sterols, marine shrimp seem also to have a dietary requirement for phospholipids, such as lecithin. The optimum dietary levels of phospholipids for shrimp range from 1 to 3% depending on the species, life stages, and source and nature of phospholipids and, possibly, other dietary nutrients. Lecithin from soybeans is an economical and nutritionally suitable source of phospholipids for shrimp.
Among the 15 vitamins which have been identified as essential for finfish, 14 have been demonstrated through research to be dietary essentials for shrimp. Dietary requirements for several of the fat-and water-soluble vita- mins are discussed in Chapter 2. The dietary levels of various vitamins re- ported for shrimp are considerably higher than those for finfish. Whether or not shrimp have a metabolic requirement for such high levels of these nutrients or whether a substantial quantity is lost into the water during in- gestion by the shrimp is unknown. Moreover, the information available is confined to the postlarval or early juvenile stage cultured in the laboratory under well-controlled environmental conditions. Thus, in the absence of clear-cut information on the vitamin requirements of shrimp, the vitamin allowances listed in Table 13.10 are offered as guidelines for nutritionally balanced shrimp feeds (Chhorn Lim, United States Department of Agricul- ture, Diseases and Parasites Laboratory, Auburn, AL).
Shrimp respond to dietary additions of phosphorus, but in seawater they apparently are able to absorb sufficient magnesium and calcium from the
Table 13.10
Recommended Vitamin Allowances for Supplemental and Complete Practical Feeds for Shrimpa
Amount per kilogram diet
Vitamin Supplemental Complete
Vitamin A 2000 IU 4000 IU
Vitamin D 1000 IU 2000 IU
Vitamin E 50 mg 100 mg
Vitamin K 10 mg 20 mg
Thiamin 20 mg 50 mg
Riboflavin 10 mg 30 mg
Pyridoxine 30 mg 60 mg
Pantothenic acid 30 mg 80 mg
Niacin 30 mg 80 mg
Biotin 0 2 mg
Folic acid 2 mg 5 mg
Vitamin B12 0.01 mg 0.05mg
Inositol 50 mg 200 mg
Vitamin C (stable form) 100 mg 200 mg
Choline chloride 500 mg 1500 mg
aFrom Dr. Chhorn Lim, United States Department of Agri- culture, Fish Diseases and Parasites Laboratory, Auburn, AL.
water. Supplementation of shrimp diets with the trace minerals, iron, copper, zinc, selenium, and manganese, improves growth (Deshimaru and Yone, 1978). Lim has recommended the mineral allowances listed in Table 13.11 for practical feeds for shrimp.