| Knowledge of nutritional and environmental factors that influence sexual maturation of male penaeid shrimp is inadequate. Therefore, influences of these factors on the reproductive quality of male Litopenaeus vannamei was investigated in experiments under controlled conditions.; A diet consisting of 75% experimental maturation diet (containing approximately 50% protein), and 25% fresh-frozen squid produced significantly higher somatic growth of shrimp than either an equivalent combination of a commercial diet and squid, or a natural diet consisting of 60% squid and 40% bloodworms. No significant effects of stocking density, presence/absence of females, tank size-configuration, or illumination was observed on growth and survival. However, decreased sperm quality of shrimp was observed and appeared to be influenced by environmental temperature.; In a subsequent experiment, a significant effect of temperature was observed on sperm quality of L. vannamei, with higher mean sperm count and lower percentage of sperm abnormalities observed in shrimp held at 26°C, as compared to those at 29°C or 32°C.; In further investigations, sperm counts of shrimp fed 75% of the maturation diet and 25% fresh-frozen squid (control) were significantly higher than those of shrimp fed a natural diet composed of 60% squid and 40% bloodworms. In addition, sperm counts of control shrimp were higher than those of shrimp fed diets combining the same proportions of maturation diet and squid, except that supplemental nutrients within the maturation formulation were deleted to produce diets with reduced levels of vitamins, cholesterol and phospholipids (simultaneously), or astaxanthin. Dietary deficiencies also were reflected in reduced weight gain of shrimp fed the diet without supplemental vitamins and the natural diet.; In another experiment, no interaction between dietary cholesterol and phospholipids (PL), and no effect of dietary PL on sperm quality or somatic growth of shrimp was observed. However, dietary cholesterol supplementation (0.2%) significantly increased sperm counts and somatic growth, as well as altered lipid composition of muscle and hepatopancreas tissues.; Results of the present research demonstrate a significant effect of water temperature and diet on reproductive quality of male L. vannamei, and suggest avenues for further study of nutritional requirements of male penaeid broodstock. |
