International Journal of Aquaculture, 2016, Vol.6, No.21, 1
-
9
2
bacteria through the production of inhibitory compounds, improvement of water quality, enhancement of immune
response of host species, enhancement of nutrition of host species through the production of supplemental
digestive enzymes and direct uptake of dissolved organic material mediated by the bacteria (Garriques and
Arevalo, 1995; Moriarty, 1997; Vine et al., 2004; Carnevali et al., 2006; Yang et al., 2009).
This investigation was undertaken to determine the effect of graded levels of dietary G-Pro on growth, body
composition and digestive enzyme activity in common carp,
Cyprinus carpio
.
2 Materials and Methods
2.1 Feed preparation
Pelleted diets were prepared using locally procured ingredients viz. fishmeal, groundnut oil cake, rice bran and
tapioca flour. All the ingredients were sieved using ISI standard mesh No.1. G-Pro, containing yeast
(
Saccharomyces cerevisiae
) and B-complex vitamins, was obtained from Vetcare Division of Tetragon Chemie
Ltd. Bangalore. Five isonitrogenous and isocaloric diets (T
0
, T
1
, T
2
, T
3
and T
4
) were formulated incorporating 0, 1,
2, 3 and 4 g G-Pro/kg diet respectively (Table 1). Each diet was prepared separately according to Jayaram and
Shetty (1981) to obtain pellets of 2 mm diameter. G-Pro was added to the cooled dough before pelletizing. The
diets were dried in a thermostatic oven at a temperature of 40 ºC and stored at room temperature in air-tight
containers until use.
Table 1
Ingredient proportion and proximate composition (Mean ±S.E.) of experimental diets
T
0
T
1
T
2
T
3
T
4
Ingredient proportion (%)
Fishmeal
26
26
26
26
26
Groundnut cake
40
40
40
40
40
Rice bran
23
23
23
23
23
Tapioca flour
10
9.9
9.8
9.7
9.6
Vitamin-mineral mixture
1
1
1
1
1
G-Pro
0
0.1
0.2
0.3
0.4
Proximate Composition (%)
Moisture
9.25 ±0.03
9.10 ±0.02
9.15 ±0.03
9.20 ±0.02
9.25 ±0.03
Crude protein
35.03±0.09
35.08±0.05
35.06±0.06
35.11±0.07
35.09±0.10
Lipid
9.21 ±0.04
9.25 ±0.03
9.24 ±0.04
9.22 ±0.05
9.22 ±0.04
Ash
12.43 ±0.12
12.47 ±0.15
12.46 ±0.08
12.52 ±0.14
12.43 ±0.12
Crude fiber
7.73 ±0.08
7.72 ±0.06
7.76 ±0.06
7.73 ±0.04
7.73 ±0.08
Nitrogen-free extract
26.35
26.38
26.33
26.22
26.28
Gross energy (kJ/g)
15.21
15.24
15.22
15.21
15.19
2.2 Experimental set up
The growth experiment of 140-day duration was carried out in triplicate in 15 outdoor cement tanks of 25 m
3
(5x5x1 m) each, without a soil base. Ground water was used to fill the tanks, maintaining a height of 90
±
5 cm
over the experimental period. Common carp fry procured from B.R. Project Government Fish Farm, Karnataka
were reared in the Fish Farm of College of Fisheries, Mangalore and acclimated to the experimental pond
conditions. Fry of av. wt. 0.8±0.03 g were stocked at a density of 50 per tank. They were fed with the formulated
diets every day at 5% of body weight in the morning and evening in 2 equal parts. Feeding was done using plastic
trays of 25x20x5 cm kept suspended in the tanks at a depth of about 50 cm. Fish were sampled every fortnight to
measure body weight and length. The quantity of feed given was re-adjusted after each sampling, based on the
weight recorded.
2.3 Water analyses
Water samples from the experimental tanks were collected fortnightly between 09.00 and 10.00 hr for measuring
temperature, dissolved oxygen, pH, free carbon dioxide and total alkalinity. Water temperature was recorded
