Gastric evacuation evacuation rates in farmed brook trout subjected to a range of feeding conditions fed commercial pellets

A previously parameterized gastric evacuation rate (GER) model of brook trout dS(t)/dt = -rho L-L(1.31)root S-t, where S, is current stomach mass (g), L is total fish length (cm), t is time (h), and rho(L) is the rate parameter constant (g(0.5)h(-1)) was extended to describe the effects of dietary energy density E (kJ g(-1)), temperature T (degrees C), feed storage conditions (frozen and non-frozen), and the arrival of an additional meal on GER of total stomach contents. The resulting data revealed a considerable effect of E and T while feed storage conditions and the arrival of an additional meal have no effect on GER of brook trout. The GER tends to increase as the energy contents of the diet were reduced. The relationship between GER and the energy contents of diet was described by a power function of E. The GER increased exponentially as the temperature increases to a maximum value at the optimum temperature (c. 18.9 degrees C) and then declines rapidly. The optimum temperature model adequately described this temperature dependency of the GER at both low and high temperatures. The estimated parameters of E and T were then added to the GER model of brook trout as dS(t)/dt = -0.000860L(1.31)E(-0.41)e(0.08) T (1 e(1.82(T-20.6))) root S-t (g h(-1)) The model was tested to predict the stomach fullness in brook trout fed for three consecutive days. The predicted values were closely in line with the actual values of stomach fullness (r(2)= 0.987). This parameterized model can be used to predict levels of stomach fullness independent of meal size and timing, and should have useful applications in the development of feeding regimes for brook trout.