Controlling feed losses by chewing in gilthead sea bream (Sparus aurata) ongrowing may improve the fish farming environmental sustainability

Gilthead sea bream (Sparus aurata) usually chew their feed before swallowing it. Under rearing condition, this feeding behaviour generates significant feed waste in the form of pellet fragments. The study aimed to experimentally quantify feed losses by chewing considering fish weight and the feed pellet size. Gilthead sea bream with a body weight of 28-1019 g were fed with differently sized pellets (2-8 mm) from a commercial aquafeed gamma. Feed wastes were collected and data were used to create a model able to estimate the waste derived from this particular feeding behaviour. The results pointed to a substantial feed loss, which increased proportionally with fish size as the pellets are larger. Simulations for a complete ongrowing cycle carried out following the aquafeed manufacturer's recommendations with regard to pellet size revealed that feed wastes by chewing represent 8% of the feed delivered. Alternative feeding regimes based on the use of smaller pellets would lead to a significant reduction in losses (up to 50%) through chewing. Improving the feeding strategy would help to minimize waste output, increasing gilthead sea bream aquaculture sustainability. Statement of relevance: This study deals with the wastes generated by chewing in the ongrowing of gilthead seabream of different body weight fed with different pellet sizes. This is the only work modelling the losses by chewing phenomenon, also suggesting alternative feeding regimes to improve environmental sustainability of the aquaculture process. (C) 2016 Elsevier B.V. All rights reserved.