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 SDAE (kJ·kg⁻¹) and temperature (t, °C) were respectively described as: Peak VO2 = −0.1332t⁴ + 5.6612t³ −86.317t² + 581.33t − 1275.3, SDAE = −23.59t⁴ + 999.28t³ − 15303t² + 101913t − 229665 (n=650, R² = 1, 4.5<t<17.5). The results of Peak VO2 and SDAE 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).