Effects of DVAQUA® on the Growth, Survival and Immune Characteristics of Pacific White Shrimp (Litopenaeus vannamei)

Abstract

A study of the effects of DVAQUA^® on the growth, survival and immune response of  Pacific white shrimp (Litopenaeus vannamei) was conducted under laboratory and outdoor (ponds) conditions. For the laboratory experiments to determine the growth-promoting and immunostimulant effects of DVAQUA^® administration in the diet, tests were carried out with three treatments (six replicates/treatment). Each replicate consisted of 25 shrimps (8-10 g) in 500-liter tanks. The shrimp were fed four times daily at 3% body weight per day for 50 days with pelleted feed containing graded levels of DVAQUA^® (0%, 0.125% and 0.25% of the feed). After 50 days of dietary administration, shrimp fed with 0.25% DVAQUA^® had a significantly higher (P<0.05) average body weight (16.11±2.14 g) than that of the control group (14.98±2.20 g). There was no significant difference in body weights between the control group and the group fed with 0.125% DVAQUA^® (15.56±2.64 g). The survival rates of shrimp from the DV Aqua groups ranged from 88.67-95.33%, which were significantly higher (P<0.05) than that in the control group (75.33%). The immune characteristics of shrimp fed on diets containing 0.25% DVAQUA^® had significantly higher (P<0.05) total hemocyte count (THC), percentage phagocytosis and superoxide dismutase activity (SOD) than the 0.125% DVAQUA^® and control groups. Shrimp fed with 0.125 and 0.25% DVAQUA^® had bactericidal activity at the serum dilution of 1:16 while the control group had the same at 1:8. Outdoor trials to determine the effect of DVAQUA^® on growth, survival and immune response in pond-reared L. vannamei were carried out in eight earthen ponds (around 1 ha or 6 rais/pond). Postlarvae 10 (PL1O) were stocked at a density of 1,000,000 PLs/pond. After 30 days, shrimp in four treatment ponds were fed with pelleted feed with 0.25% DVAQUA^® while another four ponds were fed with regular white shrimp pelleted feed as the control group. After 90 days of culture, shrimp from both the treatment and control groups were sampled for immune parameters studies. Results showed that shrimp fed with 0.25% DVAQUA^® had significantly higher THC, percentage phagocytosis, phenoloxidase, bactericidal activity and SOD (P<0.05) than those of the control group. After the shrimp were harvested, the average production and survival rate of the 0.25% DVAQUA^® group were 2,375 kg/rai and 82%, while the control group had 2,202 kg/rai and 73%, respectively. In conclusion, the present study indicated that oral administration of 0.25% DVAQUA^® for at least 30 days could increase the growth, survival and immune response of L. vannamei.