Effects of Insect Meal and Grape Marc in the Nutritional Profile, Growth, and Digestibility of Juvenile New Zealand Farmed Abalone
Generally, one of the most significant bottlenecks of land-based abalone aquaculture is the high cost of the feed, which is associated with the use of wild fish stocks to produce fish meal. Fish meal is a key ingredient used in aquaculture feeds due to its nutritional profile and palatability. Alternative ingredients, such as insect meal and grape marc, are potential candidates to be included in aquafeeds due to their suitable nutritional profile and more sustainable production. This study aimed to evaluate the effect of insect meal and grape marc on growth and nutritional profile using abalone as an animal model in a feeding trial for 165 days. Proximate analyses were used to identify nutritional variations in abalone tissue and faecal matter, and liquid chromatography-mass spectrometry and gas chromatography mass-spectrometry analyses were utilised to characterise amino acid and fatty acid composition. Results showed a 95% survival for all treatments. The inclusion of insect meal and grape marc did not affect the protein proportions of abalone tissues, but differences were found in the carbohydrate and lipid proportions. The inclusion of insect meal and grape marc significantly affected levels of amino acids L-histidine, L-methionine, and L-phenylalanine, and fatty acids oleic acid, linoleaidic acid, palmitic acid, palmitoleic acid, and α-linolenic suggesting a correlation between the feed source and fatty acid tissue composition. This work provides promising results for future optimisation of abalone diets including more affordable and sustainable alternative ingredients.