A comparative study of self-feeder and automatic feeder: effects on the growth performance of rainbow trout fry

Abstract

Growth performance of rainbow trout fry initially weighing 0.27 ± 0.09 g fed on demand by self-feeders and fed continuously by an automatic feeder was compared. Each group of 50 fish (five replicates per treatment) was fed a commercial trout feed for 44 days with a self-feeder that consisted of a highly sensitive switch and a feeder; or with an automatic feeder with two feeding schedules, 12 h (during light phase) per day and 24 h per day. The self-feeders were adjusted to release 0.02 g of food at each switch actuation. Each automatic feeding group was initially fed 0.7 g per day (5.1% of initial biomass) and this was increased twofold and threefold on days 21 and 32 respectively. Almost all feeding activity of the self-feeding groups was observed during the light phase. There was no significant effect of the feeding strategy or the feeding schedule on feed efficiency and specific growth rate, but mortality (including cannibalism) and the coefficient of variation of final fish weigh were significantly lower in the self-feeding groups. It is concluded that rainbow trout fry feed efficiently to attain growth identical to an automatic feeding fish and grow more homogeneously with self-feeders.