Frank L. Castille

Lipid nutrition of juvenile Litopenaeus vannamei I. Dietary cholesterol and de-oiled soy lecithin requirements and their interaction.

Abstract Two 6-week experiments were conducted in recirculating systems to determine dietary requirements of Litopenaeus vannamei for phospholipids (PL) and cholesterol, and their potential interaction. A 3×4 factorial design consisting of three cholesterol levels (0%, 0.2%, and 0.5% of diet) and four PL levels (0%, 1.5%, 3.0%, and 5.0% of diet) provided by de-oiled soybean lecithin (SL) was applied. Overall survival was 97.7% with no significant difference among dietary treatments. There was a highly significant interaction between PL and cholesterol on shrimp growth ( P =0.0001). Dietary cholesterol at 0.2% or 0.5% gave similar shrimp growth at any given level of PL. In a second factorial experiment, the same four levels of PL were evaluated in conjunction with smaller intervals between dietary cholesterol levels, 0%, 0.05%, 0.1%, 0.2%, and 0.4%, in an attempt to define dietary requirements and interaction better. Overall survival was 99.7%. A highly significant interaction between dietary PL and cholesterol on growth of shrimp was detected again ( P =0.0001). The cholesterol requirement was estimated to be 0.35% of diet in the absence of supplemental PL. At 1.5% and 3% PL, dietary cholesterol requirements were reduced to 0.14% and 0.13% of diet, respectively. When PL were provided at 5% of diet, 0.05% dietary cholesterol was needed for optimal growth. Shrimp growth was significantly enhanced as level of PL increased, but as the level of dietary cholesterol level increased, the growth-promoting effect of PL was diminished. Lipid composition of hepatopancreas (mid-gut gland) and muscle tissue of shrimp fed the different diets was also analyzed. Diets supplemented with PL resulted in higher total lipid in hepatopancreas and lower total lipid in muscle of shrimp than those of shrimp fed diets without supplemental PL. Interaction between dietary PL and cholesterol also affected total lipid and triglycerides (TG) in the hepatopancreas, as well as cholesterol concentration in the muscle.

A simple stress test for Penaeus vannamei postlarvae

Abstract The effects of age on resistance to low salinity and formalin stress were determined in early Penaeus vannamei postlarvae (PL) with acute static bioassays. Two-hour median lethal concentrations (2 h-LC 50 ) of formalin were 274, 288, 298 and 293 ppm for PL ages of 1, 2, 3 and 4 days (PL 1 –PL 4 ), respectively. After PL 4 , resistance to formalin increased with age to 374, 497 and 598 ppm for PL 5 , PL 6 and PL 7 , respectively. For exposure to low salinities, 2 h-LC 50 decreased from 16.8 ppt for both PL 1 and PL 2 to 14.3, 10.3. 8.3, 4.5. and 3.0 ppt for PL 3 , PL 4 , PL 5 , PL 6 and PL 7 , respectively. Based on salinity decreases or differentials, 2 h-LC 50 increased from 12.9 and 11.8 ppt for PL 1 and PL 2 , respectively, to 14.2, 18.8, 19.5, 23.3 and 24.9 ppt for PL 3 , PL 4 , PL 5 , PL 6 and PL 7 , respectively. A practical stress test to evaluate the hardiness of a hatchery produced P. vannamei PL was proposed, using exposure to a single concentration of formalin or single reduced salinity as a stressor. Because resistance to formalin and reduced salinity increased with age, different stressor concentrations are recommended for PL ages with different sensitivities. The proposed stress tests, which are rapid, inexpensive and simple, can be used by shrimp hatcheries as a quality control procedure.

Effect of variations in daily feeding frequency and ration size on growth of shrimp, Litopenaeus vannamei (Boone), in zero-water exchange culture tanks

It is generally believed that increasing feeding frequency has immediate benefits, including reduced nutrient leaching and increased shrimp growth. In this study, static-water ecoassays were conducted to determine the effect of feeding frequency and percentage of daily ration on growth of Litopenaeus vannamei and accumulation of inorganic nitrogen and phosphorus in the culture water. Shrimp were fed a semi-purified diet containing 19.5% crude protein. Experiment 1 tested five feeding frequencies (3, 5, 8, 11 and 15 feedings day -1 ) evenly spaced in time during 24 h. Daily ration was divided in similar amounts for each feeding frequency. Mean shrimp survival was 98.6% for all treatments. No significant differences were found either on shrimp growth or accumulation of total inorganic nitrogen (TIN) or total reactive phosphorus (TRP) regardless of feeding frequency. In experiment 2 daily rations were offered manually 1 (100% at 0800 h), 2 (50% each at 0800 and 2000 h), 3 (33% each at 0800, 1400 and 2000 h), 3 + (45, 20 and 35% at 0800, 1400 and 2000 h, respectively), 4 (25% each at 0800, 1200, 1600 and 2000 h), 4 + (40, 15, 15 and 30% at 0800, 1200, 1600 and 2000 h, respectively) and 6 (16.6% each at 0800, 1030, 1300, 1600, 1800 and 2000 h) times day -1 ; and with automatic feeders 15 times day 1 (every 96 min). Shrimp survival was 100% for all treatments. Although mean shrimp growth was highest at 2 feedings day no significant differences were found among feeding treatments. Accumulation of TIN in the culture water was significantly lower for tanks receiving feed 2 times day -1 compared to I and 3 times day -1 . Levels of TIN were not significantly different among the other feeding treatments. Accumulation of TRP was not significantly different regardless of feeding treatment. These data indicated that under these culture conditions increasing feeding frequency or manipulating ration size did not significantly improve shrimp survival or growth. The only significant environmental effect detected in the culture water was a reduction of TIN at a feeding frequency of 2 compared to 1 and 3 times day -1 in experiment 2. The authors suggest that multiple feedings may not be advantageous for some static culture systems, and that the cost-effectiveness of multiple feedings be evaluated for different feeds and culture systems.

Production of the Pacific White Shrimp, Litopenaeus vannamei, in High-Density Greenhouse-Enclosed Raceways Using Low Salinity Groundwater

Abstract Two nursery trials and one grow-out culture trial with Pacific white shrimp, Litopenaeus vannamei, were conducted at an inland farm near Gila Bend, Arizona, using low-salinity (1.8 to 2.6 ppt) ground-water. Trials were conducted in greenhouse-enclosed concrete raceways with bottom area of 97.5 m2 and water volume of 147.6 m3. Excellent survival (98.1±12.9%), FCR (0.7:1), and yield (2.22±0.17 kg/m2) were obtained in a five-week nursery study with stocking density of about 20,000 postlarvae/m2. In the grow-out trial, survival as high as 86% and a yield of 4.39 kg/m2 of shrimp with a mean weight of 14.7 g were achieved in 107 days from an initial mean weight of 0.5 g. These trials indicate that the Pacific white shrimp can be raised at very high densities with good survival using low-salinity groundwater. Composition of the groundwater is reported.

Effect of Dietary Supplementation of Brewer's Yeast and GroBiotic®-A on Growth, Immune Responses, and Low-Salinity Tolerance of Pacific White Shrimp Litopenaeus vannamei Cultured in Recirculating Systems

Two separate trials were conducted in clean recirculating systems at salinities of 32.9 (optimal) and 2 ppt (low-salinity challenge) to evaluate brewers yeast and GroBiotic®-A, a commercial prebiotic, as dietary supplements for growth and health management of Pacific white shrimp Litopenaeus vannamei. The growth-promoting influences of brewers yeast or GroBiotic®-A previously observed with fish were not demonstrated in these trials with shrimp, when each component was supplemented at 2% or 5% of the diet. No significant dietary effects on hematological and immunological responses—including total hemocyte count, hemolymph protein, phenoloxidase, hemocyte respiratory burst, and clearance efficiency of Vibrio harveyi—were observed in shrimp cultured at full strength salinity (30 ppt) in feeding trial 1 after a 10 week period. In a second feeding trial, dietary supplementation of GroBiotic®-A improved survival of shrimp cultured at low-salinity (2 ppt). Although the mechanism(s) for enhanced survival under low-salinity conditions by dietary immunostimulants or prebiotics have not been identified, these observations indicate potential use of prebiotics such as GroBiotic®-A for shrimp cultured in less than optimal environments.