Demand Feeders Provide a Direct Palatability Comparison for Assessing Aquaculture Diets on Cultured Yellowtail Kingfish, Seriola lalandi

This study demonstrates that demand feeders are a viable palatability tool to assess feeding preferences of yellowtail kingfish ( Seriola lalandi ) (YTK). In two trials, juvenile YTK were offered three diets simultaneously using separate demand feeders to compare diet palatability and preference. Trial 1 compared the consumption of two commercial diets (commercial diets A and B) against a negative control to determine whether YTK could operate demand feeders and exhibit a preference for specific diets. Trial 2 compared the consumption of commercial diet A against two diets containing alternative protein and lipid sources to replace marine ingredients, referred to as reduced marine ingredient (RMI) diets X and Y. During Trial 1, juvenile YTK showed a preference for commercial diet B, followed by commercial diet A, and least preferred the negative control. The higher consumption of commercial diet B and the extremely low consumption of the negative control demonstrate that YTK can both learn to operate demand feeders and exhibit feed preferences when offered multiple diets simultaneously. In Trial 2, there was no preference for any diet offered, suggesting there were no palatability issues with the RMI diets. This study demonstrated that demand feeders are a viable tool to assess feed preferences and palatability of aquaculture diets for YTK, although waste resulting from feeding behaviour negatively impacted the feed conversion ratio (FCR) achieved.