WWW.WAS.ORG • WORLD AQUACULTURE • MARCH 2015 59 the number of females that reached maturation stage IV compared to the control (Table 2). Ten females were stocked with males to obtain fertilization. The number of eggs produced by ablated females (163,000-368,000) corresponds to the fecundity of wild females (Macchi et al. 1992) and is similar to those obtained for other penaeid species. No correlation was found between the number of eggs spawned and the size of females (r=0.173). The hatching rate of fertilized eggs was between 72 and 99 percent. Tissue Carotene Content Availability of dietary carotene sources affects its content and concentration in crustaceans. In the tissues of mature wild females, a high carotene concentration was observed when compared with reared ones, probably because of the higher concentration and availability of carotenoids in the natural environment (LiñánCabello et al. 2003). Tissue carotene analysis in Argentine red shrimp indicated that non polar carotenes (β-carotene) were more abundant than polar ones (free astaxanthin), both in integument and ovary. The smaller ratio of free astaxanthin to β-carotene can be related to the biotransformation (esterification) of free astaxanthin, becoming stored as lipid globules or forming complexes of carotenoproteins (Wade et al. 2005). The concentration of total carotenes in the ovaries of Argentine red shrimp was greater than that of total carotenes found in integument, both in treated and wild animals (Table 3). Although the hypodermis and exoskeleton in crustaceans represent 60 to 90 percent of total pigments, significant quantities of pigments can be relocated during molting or maturation to other tissues such as haemolymph, midgut gland, gonads and eggs. For instance, during early maturation, free and esterified carotenes accumulate in the midgut gland but, during secondary vitellogenesis, they move from the midgut gland to the ovaries. These physiological processes generate highly reactive free radicals that are capable of destroying the integrity of cellular membranes, enzymes and nuclear DNA. Antioxidants, such as carotenoids, neutralize these highly reactive free radicals, protecting the structural and functional integrity of cells. Antioxidant protective capacity in Argentine red shrimp, measured as the decay of the DPPH radical over time, was not significantly different among treatments (Table 4). Nevertheless, antioxidant protective capacity was observed in shrimp in all treatments (Fig. 5). The efficiency of carotenoids as antioxidants does not follow their capability as radical scavengers or the order of their oxidation potential (Han et al. 2006). The long-standing controversy of the function of carotenoids as antioxidants may be related to extrapolation of properties determined in homogeneous solutions to more complex biological systems, where other factors such as spatial organization and interaction among antioxidants becomes important. TABLE 2. Percentage of full mature females of Argentine red shrimp fed different diets. Treatment % fully ripe females Control 75 Astaxanthin 100 β-carotene 100 TABLE 3. Number of eggs and percentage of nauplii obtained from females of Argentine red shrimp. Female weight (g) Number of eggs Nauplii (%) 28.2 270,000 84.6 25.6 347,775 99.3 29.0 368,750 80.0 28.4 163,000 80.8 32.2 268,500 93.1 22.5 239,000 75.0 29.6 228,800 39.3 35.0 350,000 72.0 30.9 260,000 83.0 29.9 195,000 78.0 FIGURE 5. Free radical scavenging activity of midgut gland tissues. FIGURE 4. Percentage of maturation stages of ablated (A) and non-ablated (T) females fed natural (DN) and mixed (DM) diets. (CONTINUED ON PAGE 60)
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