Effects of dietary protein and lipid levels on growth, feed
conversion and body composition in rohu, Labeo rohita (Hamilton),
fingerlings
B.B.
Satpathy, D. Mukherjee, A.K. Ray-2003
Aquaculture Nutrition, 9(1): 17-24
Abstract:
Twelve
experimental diets (D-1 to D-12) in a 4
x 3 factorial
design (four protein levels: 250, 350, 400 and 450 g kg-1
and three lipid levels: 50, 100 and 150 g kg-1) were
formulated. Carbohydrate level was constant at 250 g kg-1.
Rohu fingerlings (average wt. 4.3 ± 0.02 g) were fed the
experimental diets for 60 days in three replicates at 2% BW day-1.
Weight gain (%), specific growth rate (% day-1) and feed
gain ratio (FGR) indicated that diets containing 450 g kg-1
protein and 100 or 150 g kg-1 lipid (diets D-11 and
D-12) resulted in best performance, although results were not significantly
different from those of diet D-9 (400 g kg-1 protein
and 150 g kg-1 lipid). Protein efficiency ratio was
highest with diets D-6 (350 g kg-1 protein and 150 g kg-1
lipid) and D-9 (400 g kg-1 protein and 150 g kg-1
lipid) (P > 0.05) and declined with higher and lower
protein diets at all levels of lipid tested. Elevated lipid level (50, 100
or 150 g kg-1) did not produce better FGR in diets
containing 400 and 450 g kg-1 dietary protein (P > 0.05).
The combined effects of protein and lipid were evident up to 400 g kg-1
protein. Growth and FGR showed consistent improvement with increased lipid
levels from 50 to 150 g kg-1 at each protein level
tested except with diets containing 450 g kg-1 protein.
Apparent nutrient digestibility (for protein, lipid and energy) did not show
significant variation among different dietary groups (P > 0.05).
Whole body protein and lipid contents increased significantly (P > 0.05)
with dietary protein level. The results of this study indicate that rohu
fingerlings are adapted to utilize high protein in diets with varying
efficiency. The fish could utilize lipid to spare protein but there is no
significant advantage from this beyond the dietary protein level of 350-400 g kg-1
in terms of growth and body composition.
(Central Institute of Freshwater Aquaculture,
Kausalyaganga, Bhubaneswar, Orissa, India)