Feed intake of Atlantic salmon parr Salmo salar L. in relation to temperature and feed composition

The design and testing of a feed intake monitoring system based on feed waste collection is described. The system was used in a study of feed intake and growth of Atlantic salmon Salmo salar L. parr in relation to temperature (2degreesC or 8degreesC) and feed composition (21% fat, 50% protein and 22.5 MJ kg(-1) or 34% fat, 40% protein and 24.8 MJ kg(-1) ). Fish had lower feed intake and slower growth at the lower temperature, but temperature-corrected growth (TGC) was better in fish held at the lower temperature. There was an increase in TGC over time at low temperature, probably as a result of long-term thermal acclimation. Feed conversion for an increase in body size from 19 to 38 g was better for the fish held at low temperature. Feed consumption of low-fat feed was higher than that of high-fat feed, and growth of the fish fed the low-fat feed was better at the higher temperature. These data are consistent with the ideas that the fish compensated for differences in feed energy densities to maintain energy and nutrient intakes, and that lipostatic factors may be operating to regulate feed intake and growth.