Time-restricted self-feeding causes fin damage of Atlantic salmon

Abstract

The way in which the feed is delivered mainly influences the growth rates and feed efficiency. Restricting the time during which food is available from a self-feeder may help to regulate production parameters, but may also increase competition. In this article, the effects of time-restricted self-feeding on growth, feeding behavior and fin index Atlantic salmon (Salmo salar) were studied over the course of 6 weeks. A total of 150 fish were divided into two groups in triplicates: One group had free access to self-feeders (FA), and the other group received three meals (2 h per meal) restricted to dawn, midday and dusk a day in light phase (TR). The results showed that there were no significant differences in production parameters (specific growth rate 1.33 ± 0.21 and 1.40 ± 0.21 % day−1, for TR and FA, respectively), body composition and nutrient retention efficiencies between treatments, while the FA fish had significantly higher food wastage (0.79 ± 0.06 vs. 0.56 ± 0.10 %) compared with the TR fish. In the course of the experiment, the TR fish gradually improved the accuracy of trigger actuation; in 1–2, 3–4 and 5–6 weeks, 61, 68 and 80 % trigger actuations happened in the feeding window. Nevertheless, there was a significant decrease in the dorsal fin index found in the TR fish as the experiment proceeded (9.83 ± 0.15 and 8.56 ± 0.04 for the beginning and end, respectively; P < 0.05). The results indicate that time-restricted self-feeding causes fin damage on Atlantic salmon but has little effect on their growth. One should cautiously apply a complex self-feeding regime during production.