TY - JOUR

T1 - Effects of stocking density and sustained aerobic exercise on growth, energetics and welfare of rainbow trout

A1 - McKenzie,David J.

A1 - Höglund,Erik

A1 - Dupont-Prinet,A.

A1 - Larsen,Bodil Katrine

A1 - Skov,Peter Vilhelm

A1 - Pedersen,Per Bovbjerg

A1 - Jokumsen,Alfred

AU - McKenzie,David J.

AU - Höglund,Erik

AU - Dupont-Prinet,A.

AU - Larsen,Bodil Katrine

AU - Skov,Peter Vilhelm

AU - Pedersen,Per Bovbjerg

AU - Jokumsen,Alfred

PB - Elsevier BV

PY - 2012

Y1 - 2012

N2 - Two stocking densities, “low” (L, between ~19 and ~25 kgm−3) and “high” (H, between ~75 and ~100 kgm−3) were compared for effects on specific growth rate (SGR), feed conversion, energetics and welfare of rainbow trout reared at 14 °C either in static water (S) or swimming in a gentle current of ~0.9 bodylengths s−1 (C). Trout (initialmass ~110 g)were reared for 9 weeks in circular tanks (volume 0.6 m3), in triplicate of four conditions (LS, LC, HS, HC). Fish were fed ad-libitum daily; waste pellets were swirl-collected at the outflow to calculate <br/>feed intake. SGR was measured each three weeks for the last six weeks of the trial. The tanks functioned as intermittent-stopped flow respirometers, to permit metabolic rate to be measured as instantaneous oxygen uptake once per hour. Mean (±SD) SGR was significantly lower at H than L (1.51±0.03 vs 1.44±0.04% <br/>day−1, respectively, n=6) and lowest in HC. When compared over a similar interval of mass gain, H groups had approximately 25% higher metabolic rates than L, with the highest rates in the HC condition. As a result, fish in the H groups dissipated a greater amount of feed energy as metabolism and, across all groups, there was a direct negative relationship between the quantity of energy dissipated and their SGR. There was no evidence of a neuroendocrine stress response, plasma cortisol was around 1 ng ml−1 in all conditions. An acute crowding stress increased plasma cortisol to above 120 ng ml−1 in all groups, but C groups recovered to control levels within 8 h whereas S groups required 20 h. Respirometry on individuals revealed that H fish had approximately 14% higher metabolic rates than L fish, indicating that increased metabolic rate in rearing tanks was in part physiological. TheHgroups had approximately 15% lower critical swimming speeds than the L groups which, together with their raised metabolic rate, indicated a physiological impairment. Thus, high density <br/>reduced SGR by raising energy dissipation, at least partially as a physiological response by the fish, although there was no evidence of an endocrine stress response. The only beneficial effect of C was in recovery from acute stress

AB - Two stocking densities, “low” (L, between ~19 and ~25 kgm−3) and “high” (H, between ~75 and ~100 kgm−3) were compared for effects on specific growth rate (SGR), feed conversion, energetics and welfare of rainbow trout reared at 14 °C either in static water (S) or swimming in a gentle current of ~0.9 bodylengths s−1 (C). Trout (initialmass ~110 g)were reared for 9 weeks in circular tanks (volume 0.6 m3), in triplicate of four conditions (LS, LC, HS, HC). Fish were fed ad-libitum daily; waste pellets were swirl-collected at the outflow to calculate <br/>feed intake. SGR was measured each three weeks for the last six weeks of the trial. The tanks functioned as intermittent-stopped flow respirometers, to permit metabolic rate to be measured as instantaneous oxygen uptake once per hour. Mean (±SD) SGR was significantly lower at H than L (1.51±0.03 vs 1.44±0.04% <br/>day−1, respectively, n=6) and lowest in HC. When compared over a similar interval of mass gain, H groups had approximately 25% higher metabolic rates than L, with the highest rates in the HC condition. As a result, fish in the H groups dissipated a greater amount of feed energy as metabolism and, across all groups, there was a direct negative relationship between the quantity of energy dissipated and their SGR. There was no evidence of a neuroendocrine stress response, plasma cortisol was around 1 ng ml−1 in all conditions. An acute crowding stress increased plasma cortisol to above 120 ng ml−1 in all groups, but C groups recovered to control levels within 8 h whereas S groups required 20 h. Respirometry on individuals revealed that H fish had approximately 14% higher metabolic rates than L fish, indicating that increased metabolic rate in rearing tanks was in part physiological. TheHgroups had approximately 15% lower critical swimming speeds than the L groups which, together with their raised metabolic rate, indicated a physiological impairment. Thus, high density <br/>reduced SGR by raising energy dissipation, at least partially as a physiological response by the fish, although there was no evidence of an endocrine stress response. The only beneficial effect of C was in recovery from acute stress

U2 - 10.1016/j.aquaculture.2012.01.020

DO - 10.1016/j.aquaculture.2012.01.020

JO - Aquaculture

JF - Aquaculture

SN - 0044-8486

VL - 338-341

SP - 216

EP - 222

ER -