Aurantiochytrium sp. Meal as Feed Additive for Pacific White Shrimp Reared under Low Temperature and Challenged by WSSV in Association with Thermal Stress

A study was conducted to test the inclusion of Aurantiochytrium sp. meal in the rearing of Penaeus vannamei grown in a clear water system and at a suboptimal temperature of 22 degrees C. The doses tested were 0 (control), 1, 2, 3, and 4% at a stocking density of 100 shrimp/m(3). Rearing was carried out with aeration and individual heaters, and seawater temperature was controlled with a chiller. After nine weeks, shrimp were weighed and hemolymph was collected for hemato-immunological tests, and growth performance were calculated. Shrimp raised at 22 degrees C and fed a 1% of dietary supplementation of Aurantiochytrium sp. meal were superior in immunological parameters. After the dietary assay, a total of 42 shrimps (10.9 +/- 0.06 g) per treatment were infected with White Spot Syndrome Virus (WSSV). They were orally infected with 2.6 +/- 10(6) virus particles per g of the animal, maintained at a suboptimal temperature of 22 degrees C for 108 h, and acclimated to an optimal temperature of 28 degrees C for an additional 48 h. At 7 days post infection, surviving shrimp were collected for hemato-immunological analysis. Cumulative mortality results showed that shrimp fed diets containing 3% and 4% Aurantiochytrium sp. meal had higher survival than other treatments when challenged with WSSV.