Nitrogen Metabolism and its Relationship with the Nutritional Requirements of Peneid Shrimp.
Due to the importance of its role, there are numerous published works which have focused on determining the dietary requirement of different aa for penaeid shrimp, added to the diet in crystalline form. The most studied aa have been Arginine (Teshima et al., 1986; Chen et al., 1992), mixtures of essential aa (Threonine, Valine, Methionine, Isoleucine, Leucine, Phenyl Alanine, Lysine, Histidine, Arginine and Tryptophan; Teshima et al., 1986; Divakaran, 1994), Methionine (Teshima et al., 1992), Lysine (Hew and Cuzon, 1982; Fox et al., 1995), Threonine (Millamena et al., 1997), Proline ( Smith and Dall, 1991). Most of these authors agree that crystalline aa are assimilated with greater efficiency than aa linked to the peptides of a protein. The concentration of these supplementary aa can increase the concentration of ALA which can be quickly used as an energy source (Cowey and Forster, 1971; Cowey and Sargent, 1979). The pool of ALA in decapods is comparable to that of vertebrates with ranges ranging from 2 to 6 µmol / mL (Dall, 1975; Chen et al., 1994), which in addition to their energetic role have an important participation in the regulation of the intracellular volume where they substitute for organic ions which are the first osmotic effectors in hemolymph (Claybroock, 1983). Although studies in peneid shrimp are lacking, there is evidence that 50% of ALA are found in the hemocytes of some decapods, which has been interpreted in relation to the utility that these molecules may have as compartmentalized osmotic effectors (Miller et al., 1973 ). Thus, aa both as protein precursors, as osmotic effectors or as sources of metabolic energy are critical molecules in the metabolism of penaeid shrimp. Understanding the forms of acquisition and metabolization are fundamental aspects to understand what the conditions are nutritional and environmental conditions to obtain the best performance of shrimp in culture.
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