Effects of amino acid supplementation on the nutritive quality of fermented linseed meal protein in the diets for rohu, Labeo rohita, fingerlings
Journal
of Applied Ichthyology, 17(5): 220-226
Abstract:
A feeding trial was conducted for 8 weeks to
examine the effects of partial substitution of fish meal (FM) protein (crude
protein content: 58.5%) with linseed meal protein with and without
supplemental amino acids in diets for rohu Labeo rohita (Hamilton),
fingerlings (mean weight: 1.50 ± 0.3 g). Prior to
incorporation into the diets, linseed meal was fermented with lactic acid
bacteria (Lactobacillus acidophilus) to reduce/eliminate the
antinutritional tannin and phytic acid factors. Twelve experimental diets
(diets D1–D12) were formulated to replace the FM protein from a reference
diet (RD) with linseed meal protein at different levels (four sets of diets,
of which each set of three diets contained 25%, 50% and 75% replacement of
FM protein by linseed meal protein, respectively). Diets D1–D3 were not
supplemented with any amino acid. Lysine was supplemented in diets D4–D6.
Diets D7–D9 were supplemented with methionine + cystine
(together), and diets D10–D12 contained lysine and methionine + cystine
(together). Lysine and methionine + cystine (together) were added
to the diets at 5.7% and 3.1% of dietary protein, respectively. The groups
of fish fed diets without amino acid supplementation had significantly lower
percentages of weight gain, specific growth rate and high feed : gain
ratio than the fish groups fed other experimental diets. The addition of
lysine and methionine + cystine to the diet in which 50% of the FM
protein was replaced by linseed meal protein (diet D11) significantly
improved fish performance. The results of the present study suggest that
rohu fingerlings can effectively utilize the supplemented amino acids and
that linseed meal protein can replace up to 50% of the FM protein in rohu
diets if the linseed meal is properly processed (fermented) and supplemented
with the lacking amino acids.
(Fisheries Laboratory, Department of Zoology, Visva-Bharati University,
Santiniketan, West Bengal, India)