Butylated hydroxytoluene: its effect on the quality of shrimp diet stored at various temperatures and on growth and survival of Penaeus monodon juveniles

Abstract

Shrimp diets with and without the antioxidant, butylated hydroxytoluene (BHT) were stored at 10°, 20°, 28°–30°, and 40°C for 10 weeks. To monitor lipolysis and lipid oxidation, free fatty acid (FFA) content, peroxide values (PVs), and malonaldehyde (MAL) levels were measured from the extracted lipids of the stored diets. Fatty acid levels of the diets increased between the initial and final samplings and the increase was higher (8.4%) in diets without BHT stored at 40°C after 10 weeks. Peroxide values of the extracted lipids were low and fluctuated monthly between 2.2 and 7.4 mmol/kg fat. MAL levels increased in diets with and without BHT except those stored at 10°C for 4 weeks. Diets with BHT stored at 10°C had the lowest (8.7 mg MAL/kg fat) MAL levels and diets without BHT stored at 40°C for 10 weeks had the highest (16.9 mg MAL/kg fat). Shrimp fed diets with BHT gained 5.7–6.4× their initial weight after 10 weeks of rearing. Their growth was significantly better than those fed diets without BHT (4–6×) during the 60-day culture period. Survival was significantly higher in those fed diets with BHT (87–88%) than those without BHT (75–85%). No hepatopancreatic lesions were seen in shrimp samples fed diets with and without BHT and stored at various temperatures. The incorporation of BHT in shrimp feed is necessary if the feed is to be stored at 40°C for 10 weeks.