Effects of Feed Processing Type, Protein Source, and Environmental Salinity on Litopenaeus vannamei Feeding Behaviour

Abstract

In an 8-week trial, the effects of feed processing types (extruded vs. steamed pellets) and protein source (soya/pea vs. fish meal) on Litopenaeus vannamei were studied under 30 ppt (first 30 days) and 5 ppt (last 15 days) salinity conditions. Diets included D1-SE soya/pea extruded, D2-SS soya/pea steamed, D3-FE fishmeal extruded, and D4 (FS) fishmeal steamed pellets. No significant weight differences were observed. Survival rates (80-97% at 30 ppt) decreased at reduced salinity and were significantly higher for shrimp fed steamed pellets (D2:80.00%, D4:76.67%) compared to extruded (D1: 50.00%, p<0.05). Shrimp fed D2-SS and D4-FS diets had increased lipid content (6.79%, 6.36%, p<0.05). Significantly lower lysine and isoleucine were noted in D2-SS. Behaviourally, at 30 ppt, D3-FE attracted significantly more shrimp (84.72%) than D1-SE (74.49%) and D2-SS (75.70%, p<0.05). Click analysis showed D1-SE and D2-SS with the shortest durations (17.97, 17.24ms, respectively), and D3-FE and D4-FS the longest (20.10, 23.89ms, respectively, p<0.05). Click frequency was also significantly higher in fishmeal-based diets, whereas the number of clicks was higher in shrimp fed extruded feed. Overall, extruded pellets and fishmeal diets were more favourable. These findings emphasize the importance of tailored feed strategies that consider nutritional content, feed physical properties and environmental factors for optimal shrimp feeding.