Effect of dietary protein level, feeding frequency and amount of food offered on growth and gastric evacuation of Oreochromis mossambicus fry
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Date
2012
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Publisher
University of Zululand
Abstract
Excess protein in fish diet may be wasteful and unnecessarily expensive.
Furthermore, when fish are fed insufficiently or excessively, their growth or feed
efficiency may decrease, resulting in increasing production costs and water
quality deterioration. Therefore this study was conducted to determine the
optimum dietary protein level, feeding frequency and feeding rate on growth,
gastric and intestinal evacuation of O. mossambicus fry under hatchery
conditions, in order to reduce the production costs while optimizing growth rate.
Diets contained 20%, 30%, 35%, 40% and 45% protein levels, feeding frequency
of once, twice, thrice, four times and five times per day and feeding rates of 10%,
15%, 20%, 25% and 30% body weight per day were tested in separated
experiments conducted in a temperature and light cycle controlled environmental
room. The results indicated that both dietary protein level and feeding frequency
had a significant effect on weight gain, specific growth rate and gross food
conversion ratio (ANOVA, P<0.05) but not survival rate (ANOVA, P>0.05).
Feeding rate had a significant effect on weight gain and gross food conversion
ratio (ANOVA, P<0.05) but not on specific growth rate and survival rate (ANOVA,
P>0.05). A diet containing 30% protein level, feeding frequency of four times per
day and 15% of the fry body weight per day were the optimal levels obtained
from the growth experiments. Dietary protein level had a significant effect on
gastric and intestinal evacuation (ANOVA, P<0.05); feeding frequency had a
significant effect on intestinal evacuation rate and time (ANOVA, p<0.05) only but
not on gastric evacuation rate and time (ANOVA, P>0.05), while feeding rate had
no significant effect on both gastric and intestinal evacuation rate and time
(ANOVA, P>0.05). The optimum levels obtained in gastric and intestinal
evacuation are 40% dietary protein level, feeding frequency of twice per day and
a feeding rate of 15% body weight per day.
Description
Submitted to the Faculty of Science and Agriculture in partial fulfillment of the requirements for the Degree of Master of Science in the Department of Zoology at the
University of Zululand, South Africa, 2012.
Keywords
Protein levels, Oreochromis mossambicus fry