Evaluating Feed Intake of Fishes in Aquaculture Nutrition Experiments with Due Consideration of Mortality and Fish Survival

摘要

Mortality is normal and natural in aquaculture experiments. However, it becomes a problem when measuring feed intake as a component of nutrient utilization parameters such as: feed conversion ratio, feed conversion efficiency, apparent net protein utilization, protein efficiency ratio and protein productive value. In order to accurately evaluate feed intake with due consideration of mortality encountered, a formulae was developed using empirical data obtained from an experiement that had mortality. The formulae was: total feed consumed by numbers of survived fishes=DL∑ni=1(Fi/Ni). Where, D=Numbers of days fishes were fed within each period before it was adjusted (e.g fortnight), it was constant throught period of experiment; F=Uantity of feed fed per day for a fortnight before the quantity was adjusted, it changed every fortnight; L=Numbers of living fishes at the end of experimental period;N=Numbers of fishes at each weighing period, it might change every fortnight or might be constant if no mortality occurred;while n=Numbers of times fishes were weighed and quantity of feed was adjusted but this did not include the final weighing at the termination of experiment. However, if the fishes were weighed weekly, then D=6.