Effects of temperature on the SDA of the brook trout

Specific dynamic action (SDA), the metabolic phenomenon resulting from the digestion and assimilation of a meal, is generally influenced by temperature. The effects of temperature (5.5±0.5, 8.5±0.5, 11.5±0.5, 14.5±0.5, 17.5±0.5°C) on SDA of brook trout (Salvelinus fontinalus Mitchill) was evaluated, by measuring the temporal pattern of the oxygen consumption rates, after feeding. Peak VO₂ (highest recorded oxygen consumption rate following feeding) and SDAE (energy expended on SDA) increased slowly to a maximum at 14.5±0.5°C, and then decreased at 17.5±0.5 °C. The relationships between Peak VO₂ (mg·kg^-1·h^-1), the SDA_E (kJ·kg^-1) and temperature (t, °C) were respectively described as: Peak VO₂ = -0.1332t⁴ + 5.6612t³ -86.317t² + 581.33t - 1275.3, SDA_E = -23.59t⁴ + 999.28t³ - 15303t² + 101913t - 229665 (n=650, R² = 1, 4.5<;t<;17.5). The results of Peak VO₂ and SDA_E showed that the optimum growth of brook trout occurred at 14.5±0.5□. Duration decreased from 28±0.7h to 16±0.6h as the temperature increased from 5.5±0.5 to 17.5±0.5°C. The relationship between duration (h) and temperature (t, °C) was described as: duration = -0.0051t⁴ + 0.2305t³ - 3.767t² + 25.724t -33.167, (n=650, R² = 1, 4.5<;t<;17.5).