64 Safina Musa, Christopher Mulanda Aura and Rodrick Kundu
feeding efficiency (FE) and specific growth rate (SGR) was observed in
H35 suggesting that the main component in diet which influences growth
is protein. Feed intake was inversely related to the dietary lipid level
suggesting that high lipid levels could affect appetite of fish. There was
no significant interactive effect of protein and lipid on WG (%), SGR,
and feed intake (FI) indicative that O. niloticus can efficiently utilize
carbohydrate better than lipid. High lipid level enhanced high
viscerasomatic index (VSI) and intraperitoneal fat (IPF) indicating that
fish fed with high lipid diets were unable to utilize the entire lipid for
energy production and the excess fat was deposited in the viscera. The
current study suggests that the recommended maximum level of crude
protein, lipid and feeding level to maintain the welfare and maximum
growth of O. niloticus is between 25 and 35%, 8% lipid level and feeding
rate between 70 and 100% in a practical world.Keywords: Oreochromis niloticus, protein, lipid, feeding rate, growth
performance
INTRODUCTION
Fish feed accounts for over 50% of the total cost of fish production and is
a major constraint to fish farming in resource poor regions (Craig and
Helfrich, 2002; Ali et al., 2009). Protein usually is the most expensive nutrient
yet it is also the most important factor affecting growth performance of fish
(Lovell, 1989; Tacon, 1993; Fotedar, 2004). Majority of fish feeds contain fish
or shrimp meal as the main source of dietary animal protein. Major source of
fishmeal being the ever diminishing capture fishery, the sustainability of the
aquaculture sector is questioned (Naylor et al., 2000). The sustainability of the
aquaculture industry cannot be achieved unless progressive reduction of wild
fish inputs into fish feed is addressed (Naylor et al., 2000; Liti et al., 2005;
Munguti et al., 2009). Presently, substituting fishmeal with plant protein
sources in fish diets is becoming a common practice in order to minimize feed
costs (El-Saidy and Gaber, 2004; Hernandez et al., 2010; Olivera et al., 2011;
Richie and William, 2011). The results show great variation in the degree of
success for partial or complete substitution depending on the ingredient of the
test feeds as well as species of fish under culture. Even though fish are known
to be good convertors of dietary protein, considering the rapid growth of
aquaculture and the sky-rocketing of the feed cost, there is necessity for
improvement of dietary protein utilization.