BAOJ Aquaculture - Bioaccent

BAOJ Aquaculture Manoj Kumar B, BAOJ Aquaculture 2018, 1: 1 1: 003

Research

‘Stafac-20’ Effect on Growth and Body Composition in Catla (Catla catla) and Rohu (Labeo rohita) Fry Manoj Kumar B1 and Keshavanath P2* College of Fisheries, Kerala University of Fisheries and Ocean Studies, Panangad-682506, Kerala, India

1

College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University,

2

Mangalore-575002, Karnataka, India

Abstract The growth promoting effect of Stafac-20, a commercial growth promoting feed additive containing 2% virginiamycin, was investigated in fry of Indian major carps, catla (av. wt. 0.16+0.02 g) and rohu (av. wt. 0.14+0.01 g) separately. Stafac-20 was added at 0, 20, 40, 60, 80 and 100 ppm levels to the basal diet having 35% protein, prepared incorporating fish meal, groundnut oilcake, rice bran, tapioca flour and vitaminmineral mixture. The fry stocked @ 50 in 25 m3 outdoor cement tanks were fed daily on these test diets in triplicate, over a period of 63 days. The additive resulted in significant (P≤0.05) increase in fish weight, the best being with Stafac-20 inclusion of 60 ppm in catla and 100 ppm in rohu. The highest fish survival, feed conversion efficiency, RNA: DNA ratio, net fish production, and carcass protein and fat content were obtained in these two treatments. The results reveal the beneficial effects of adding Stafac-20 to the diet of catla and rohu fry.

Keywords: Stafac-20, Catla, Rohu, Growth, Body Composition Introduction The stagnating capture fisheries production is confronted with a growing demand for fish due to population growth and an increase in the per capita fish consumption. Therefore, the aquaculture industry carries the responsibility of increased fish supply. Artificial diets play an important role in enhancing fish production from aquaculture. It is estimated that the total feed cost in culture accounts for over 50% of the production cost [1], depending upon the type of culture and the intensity of feeding. Use of growth promoters in aquaculture diets has become popular in recent years as it reduces the culture period and thereby the total feed cost. The most utilized growth promoting agents are probiotics, prebiotics, hormones, antibiotics, ionospheres and some salts. In-feed antibiotic virginiamycin is considered a growth promoter. Studies carried out with virginiamycin have yielded a 30-50% increase in growth rate and a significant improvement in feed utilization efficiency [2-7].

BAOJ Aquaculture, an open access journal

The hypotheses put forth on the mode of action of antibiotics are: (i) they may destroy harmful bacteria in the intestine or those bacteria that compete for host nutrients or alternatively enable increased occurrence of beneficial bacteria that synthesize growth factors and (ii) they may enhance the efficiency of intestinal absorption and nutrient utilization, possibly by decreasing the thickness of the intestinal wall [8,9]. Catla (Catla catla) and rohu (Labeo rohita) are the two most popular cultured Indian major carps. These carps belong to the family Cyprinidae. Catla is a fish with large and broad head, a large protruding lower jaw, and an upturned mouth. It has large, greyish scales on its dorsal side and whitish on its belly. It is a surface feeder, young ones feeding on zooplankton and phytoplankton. Body of rohu is bilaterally symmetrical, moderately elongate, its dorsal profile more arched than the ventral profile. Body has cycloid scales, head without scale; snout fairly depressed, projecting beyond mouth; mouth small and inferior; lips thick and fringed with a distinct inner fold to each lip. Rohu is essentially an herbivorous column feeder, preferring algae and submerged vegetation. Both the species readily accept artificial diets. There is paucity of information on the effect of virginiamycin in carps and studies with catla or rohu fry are totally lacking. Hence, the present *Corresponding Author: Keshavanath P, College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Mangalore-575002, Karnataka, India, E-mail: perarkeshavanath@ yahoo.co.in Sub Date: February 1st, 2018, Pub Date: February 15th, 2018.

Acc Date: February 14th, 2018,

Citation: Manoj Kumar B and Keshavanath P (2018) ‘Stafac-20’ Effect on Growth and Body Composition in Catla (Cata catla) and Rohu (Labeo rohita) Fry. BAOJ Aquaculture 1: 003. Copyright: © 2018 Manoj Kumar B. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Volume 1; Issue 1; 003

Citation: Manoj Kumar B and Keshavanath P (2018) ‘Stafac-20’ Effect on Growth and Body Composition in Catla (Cata catla) and Rohu (Labeo rohita) Fry. BAOJ Aquaculture 1: 003.

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investigation was undertaken to determine the effect of graded levels of Stafac-20, containing 2% virginiamycin, on growth and body composition in them.

level to the cooled dough and thoroughly mixed before pelletizing, using a 2 mm diameter die. The pellets were dried in an oven at a temperature of 40 ºC and stored at room temperature in air-tight containers until use.

Materials and Methods

Experimental Set Up

Feed Preparation

Two experiments of 63-day duration each were carried out in triplicate in different sets of 18 outdoor cement tanks of 25 m3 (5x5x1m) each, without a soil base. Ground water was used to fill the tanks, maintaining a depth of 90+5 cm through the experimental period, adding fresh water to replenish evaporation loss. Catla and rohu fry procured from B.R. Project Government Fish Farm were reared in the Fish Farm of the College of Fisheries, Mangalore and acclimated to the experimental conditions. Catla and rohu fry of average weight 0.16+0.02 and 0.14+0.01 g respectively were stocked at a density of 50 per tank. They were fed with the experimental

Pelleted diets were prepared using locally procured ingredients viz. fishmeal, groundnut oil cake, rice bran, tapioca flour and vitaminmineral mixture (Nuvamin forte). All the ingredients, except the vitamin-mineral mixture, were sieved using ISI standard mesh No.1and their proximate composition determined (Table 1). Commercially available Stafac-20, containing 2% virginiamycin, was the feed additive used. Six isonitrogenous and isocaloric diets (T0, T1, T2, T3, T4 and T5) were formulated incorporating 0, 20, 40, 60, 80 and 100 ppm Stafac-20 respectively (Table 2). Each diet was prepared separately by mixing the required quantity of ingredients with water adequate to prepare the moist dough which was heated at 105 ºC for 30 minutes and then cooled [10]. Staffac-20 powder and vitamin-mineral mixture was added at the requisite

diets every day at 10% 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 once every 3 weeks to measure body weight and length. The quantity of feed

Table 1. Proximate composition (%, Mean+ S.E.) of ingredients used in feed formulation Fish meal

Groundnut cake

Rice bran

Tapioca flour

Moisture

7.96 + 0.12

8.67 + 0.17

11.96 + 0.19

12.33 + 0.03

Protein

60.73 + 0.27

41.92 + 0.14

9.56 + 0.04

3.51 + 0.02

Lipid

9.24 + 0.06

11.09 + 0.07

9.64 + 0.06

0.92 + 0.01

Ash

18.91 + 0.17

3.58 + 0.06

25.48 + 0.18

1.67 + 0.04

Fibre

0.36 + 0.03

6.40 + 0.05

30.80 + 0.12

3.50 + 0.06

Nitrogen-free extract

2.79

29.01

26.46

79.05

Gross energy (kJ/g)

16.65

17.79

10.05

14.30

Table 2. Ingredient proportion (%) and proximate composition of (%, Mean+ S.E.) of the basal diet Ingredient proportion (%)

Proximate composition of basal diet (%)

Fish meal

26

Moisture

9.25 +0.03

Groundnut cake

40

Crude protein

35.03+ 0.09

Rice bran

23

Lipid

9.22 + 0.04

Tapioca flour

10

Ash

12.43 + 0.12

Vitamin-mineral mixture*

1

Crude fibre

7.73 + 0.08

Stafac-20 (ppm)

0

Nitrogen-free extract

26.35

Gross energy (kJ/g)

15.22

*Nuvamin forte BAOJ Aquaculture, an open access journal

Volume 1; Issue 1; 003


given was re-adjusted after each sampling, based on the weight recorded.

Water Analyses Water samples from the experimental tanks were collected on fish sampling days between 09.00 and 10.00 hr for measuring temperature, dissolved oxygen, pH, free carbon dioxide and total alkalinity. Water temperature was recorded using a digital thermometer and pH was measured with a digital pH meter (LI-120, ELICO, India). Dissolved oxygen, free carbon dioxide and total alkalinity were determined following standard procedures [11]. Plankton samples were also collected along with water samples, using a net made of No. 30 bolting silk cloth having 60 µm mesh size, by filtering 100 liters of water from different locations of each experimental tank. Dry weight of plankton was determined by drying the filtrate overnight in a hot-air oven at 80 ºC.

Estimation of Muscle DNA and RNA Muscle DNA was determined by the diphenylamine method [12], while RNA was estimated as described by Ceriotti [13]. Proximate Composition Proximate composition of the feed ingredients, diets and fish carcass was analyzed. Protein, fat, fiber and ash were determined following standard procedures [14]. NFE was obtained by the ‘Difference method’ [15]. The energy content was calculated by multiplying protein, fat and carbohydrate (NFE) content by factors of 5 [16], 9 and 4 [17] respectively and expressed in kJ/g. Performance Indices and Statistical Analysis Specific growth rate (SGR), feed conversion efficiency (FCE) and net production was calculated using the following formulae. SGR= [ln final weight - ln initial weight/Experimental duration in days] × 100. FCE= Fish weight gain (g)/Feed consumed (g) x100. Net production (g) = Gain in body weight (g) x Number of fish harvested. Comparison among treatments for various parameters was done by oneway analysis of variance (ANOVA), followed by Duncan’s multiple range test at P≤0.05 [18,19].

Results The range of water quality parameters monitored over the duration of the first experiment conducted with catla was as follows. Temperature: 28 to 29 °C, pH: 7.4 to 8.8, dissolved oxygen: 4.40 to 9.6 ppm, free carbon dioxide: nil to 1.2 ppm and total alkalinity: 38 to 68 ppm, respectively. The BAOJ Aquaculture, an open access journal

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average plankton wet and dry weight values varied from 5.33 to 20.64 mg and 1.96 to 6.98 mg per 100 L. In the second experiment carried out with rohu, the monitored water quality parameters varied as follows. Temperature: 28 to 29.5 °C, pH: 7.2 to 8.4, dissolved oxygen: 6.0 to 9.2 ppm, free carbon dioxide: nil to 1.8 ppm and total alkalinity: 40 to 95 ppm, respectively. The average plankton wet and dry weight values ranged from 5.26 to 17.36 mg and 1.75 to 5.09 mg per 100 L. On termination of the experiment, the best average growth of catla was observed in T3 treatment (10.24 g), followed by T2 (10.13 g), T5 (8.30 g), T4 (8.01 g), T1 (7.27 g) and T0 (7.20 g) (Table 3). The difference in weight of fish from T2 and T3 treatments was not significant, but they were significantly (P≤0.05) higher from the rest of the treatments and the control. Final body weight of fish from T4 and T5 treatments was significantly higher than those of T1 treatment and control. The average SGR ranged from 6.04% (T0) to 6.60% (T3). Survival of fish was the highest (70.66%) in T3 treatment. Also, the highest net fish production was obtained in this treatment (Table 3). FCE was the best under T3 treatment (45.71%). Carcass fat content was the highest in fish from T3 treatment (2.03%) as against the lowest of the control (1.49%). While protein values showed marginal increase in treated fish, ash content was found to be lower in them. Rohu fry receiving Stafac-20 incorporated diet showed dose dependent growth response. The best average growth of rohu was recorded in T5 treatment (11.36 g), followed by T4 (10.99 g), T3 (10.67 g), T2 (9.95 g), T1 (9.78 g) and T0 (9.37 g) (Table 4). Fish under T3 T4 and T5 treatments differed significantly (P≤0.05) from the control in terms of final weight, the percentage increase in growth being 13.87, 17.29 and 21.24 respectively over the control. The final weight of fish in these treatments also differed significantly from those of T1 and T2 treatments. The average SGR varied from 6.63% (T0) to 7.22% (T5). The highest survival of fish (60%) was noticed in T4 and T5 treatments; it was the least in the control (40%). The highest net fish production was obtained in T5 treatment (Table 4). FCE was the best in T5 treatment (34.67%) and the least in the control (23.58%). Protein and fat contents were the highest in fish under T5 treatment (18.37%, 2.92%) and the lowest in control fish (17.41%, 1.72%).

Discussion The water temperature recorded was within the range of 28-32 ºC, suggested as ideal for tropical major carps [20]. pH varied from 7.2 to 8.8. In general, an aquaculture pond should have a pH range between 6.5 and 9.0 [21]. Dissolved oxygen level was above 5 ppm, except on one occasion when it was 4.4 ppm; the highest value recorded was 9.6 ppm. DO level of >5ppm is essential to support good fish production [22]. Free carbon dioxide was not detected in most of the experimental tanks on different sampling days and when detected was found at low levels, the highest



level recorded being 1.8 ppm. For supporting good fish production, free carbon dioxide in water should be less than 5 mg/L [23]. Alkalinity between 75 to 200 mg/L, but not less than 20 mg/L is ideal in aquaculture [21]; desirable range of 50-150 mg/L (CaCO3) has also been suggested [24]. Alkalinity values of 38 to 95 ppm were recorded in the present study. Variation in plankton weight was not significantly different and hence their contribution to fish growth can be considered as equal among the treatments. Stafac-20 fed catla showed higher growth than that of the control; the best growth as well as the highest average SGR was recorded in T3 treatment. However, the difference in final body weight and SGR of fish from T2 and T3 treatments was not significant (P≥0.05). They showed a percentage growth increment of 40.69 and 42.22, respectively over that of the control. In rohu fry, the best results in terms of growth, SGR, survival, net fish production, RNA: DNA ratio, feed conversion efficiency, and protein and fat content of carcass were recorded in fish fed 60 to 100 ppm Stafac-20. It is interesting that treatments resulting in better growth also recorded better survival and combined together augmented net fish production (Table 4). Earlier studies with virginiamycin in Pangasius sutchi [25], common carp [2-4], rainbow trout [5] and Nile tilapia [6,7] have yielded positive results, with wide variation in the dosage. However, a study conducted with channel catfish [26] showed no effect of virginiamycin on growth performance, feed utilization efficiency and body composition at the concentrations used (0, 3, 6, 12 and 24 mg/kg). In common carp and catfish, 40 ppm virginiamycin induced optimum growth enhancement [27,25]. In fingerlings of common carp and rohu, dosages of 20 ppm and 80 ppm Stafac-20 respectively produced the best growth [4]. Significantly higher growth performance, survival rate and feed utilization efficiency was recorded in tilapia fry fed 0.1% virginiamycin supplemented diet [6]. The growth promoting effect of antibiotics is known to vary with species, age, nutritional status and environment. It is not clear how virginiamycin brings about superior growth. Possibly, it acts by destroying harmful bacteria that are potential pathogens or those which compete with the host species for food. An increase in Aeromonas hydrophila population in the intestine of common carp fed virginiamycin incorporated diet has been reported [2]. A shift in the bacterial population could affect food utilization. Enhanced lipid digestibility with antibiotic incorporated diets, irrespective of lipid and carbohydrate levels, was observed in rainbow trout [28]. Antibiotics increase the efficiency of intestinal absorption and nutrient utilization due to decreased thickness of the intestinal wall [9]. Growth enhancement in the treated fish may be due to the increased availability of nutrients due to change in the intestinal absorptive capacity. The digestion of food and absorption of


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nutrients depends on the availability and efficiency of digestive enzymes [29]. Increased activity of various digestive enzymes has been observed in Stafac-20 treated mahseer fingerlings [30]. The changes in the gut microflora/morphology stimulated by virginiamycin must have led to better feed utilization. The best feed conversion efficiency in common carp and rohu was recorded with fed 20 ppm and 80 ppm Stafac-20 respectively [4]. Increase in RNA: DNA ratios recorded in Stafac-20 treated fish can be correlated with protein synthesis. RNA: DNA ratio is a sensitive index of nutrition in fry, with minimum values in starved fish [31]. RNA: DNA ratios have been related to the tissue growth rate [32]. The proximate composition of carcass showed an increase in the protein and fat levels in rohu fry and fat in catla fry, corresponding with higher growth (Tables 3 and 4). Dietary content is the main factor affecting body composition of fish [33]. Stafac-20 being the only variable in the test diets, the differences noticed in carcass composition can be attributed to it. High deposition of fat was noticed in antibiotic-treated common carp; excess protein may have been stored as fat which can be considered as an indication of growth [2]. In the present study, significantly higher fat was found in the carcass of both the species, following Stafac-20 treatment. Studies carried out at Aston University, U.K. and by Cravedi et al. [34] have shown that virginiamycin has no residual effect in fish tissue. Based on the present findings on ‘Stafac-20’ effect on growth and body composition in catla (Catla catla) and rohu (Labeo rohita) fry, it can be concluded that in both the species the feed additive had positive influence when administered through diet. A dose of 60 ppm can be recommended for the rearing of catla fry. However, since the best growth of rohu fry was obtained with 100 ppm, the highest dose tested; there is a need to test still higher doses, before deciding on the optimum dose for this species. Acknowledgement We thank the Dean, College of Fisheries, Mangalore for providing research facilities.



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Table 3. Growth parameters (Mean +S.E.) and carcass composition of catla fed experimental diets Diets Parameter T0

T1

T2

T3

T4

T5

Final weight (g) Increment over control (%)

7.20+0.03a --

7.27+0.06a 0.97

10.13+0.12c 40.69

10.24+0.02c 42.22

8.21+0.15b 14.03

8.30+0.02b 15.28

Final length (cm)

6.61+0.01a

6.95+0.04a

7.58+0.2b

8.34+0.03c

6.97+0.06a

7.52+0.02b

Specific growth rate (%)

6.04+0.09a

6.06+0.03a

6.58+0.05b

6.60+0.02b

6.21+0.04ab

6.27+0.01ab

29.50+ 0.26a

24.70+0.84a

44.34+1.52c

45.71+0.63c

36.37+0.76b

32.66+0.42b

RNA:DNA Ratio

14.78

14.50

15.06

15.14

14.89

14.53

Survival (%)

57.30

61.66

64.00

70.66

63.33

66.00

211.76+8.15a

316.48+12.36c

354.89+7.31c

245.46+3.98ab

263.59+4.26b

Food conversion efficiency (%)

Net production (g/25m3/63 days)

198.51+6.14a

Carcass proximate composition (%) Dry matter

22.10+0.03a

22.28+0.01a

22.41+0.16a

23.77+0.01b

22.82+0.01a

23.09+0.03a

Protein

17.28+0.01a

17.29+0.02a

17.44+0.03a

17.62+0.01a

17.49+0.03a

17.57+0.03a

Fat

1.49+0.02a

1.80+0.01b

1.72+0.01b

2.03+0.01c

1.82+0.03b

1.88+0.02b

Ash

0.76+0.2b

0.66+0.02a

0.65+0.02a

0.61+0.02a

0.64+0.03a

0.63+0.04a

3.97

4.10

4.10

4.43

4.18

4.26

Calorific value (kJ/g)

Values with different superscripts in the same row indicate significant (P≤0.05) difference




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Table 4. Growth parameters (Mean + S.E.) and carcass composition of rohu fed experimental diets Diets Parameter T0

T1

T2

T3

T4

T5

Final weight (g) Increment over control

9.37+0.26a --

9.78+0.18a 4.38

9.95+0.14a 6.19

10.67+0.09b 13.87

10.99+0.11b 17.29

11.36+0.12b 21.24

Final length (cm)

7.90+0.42a

8.00+0.34a

8..75+0.92a

9.15+0.46a

9.99+0.86a

10.18+0.63a

Specific growth rate (%)

6.63+0.09a

6.70+0.03a

6.83+0.05a

6.88+0.02ab

6.93+0.04b

7.22+0.01b

23.58+ 0.32a

24.86+0.74a

24.93+0.12a

27.57+0.49b

28.24+0.86b

34.67+0.22c

RNA:DNA Ratio

3.40

4.15

5.03

5.64

5.77

6.26

Survival (%)

40.00

50.00

54.67

55.33

60.00

60.00

180.92+8.24a

238.18+11.12b

265.08+7.36bc

287.97+8.31c

322.36+2.04d

333.63+4.26d

Dry matter

21.90+0.09a

22.74+0.04b

23.19+0.03b

23.39+0.02b

23.30+0.03b

23.36+0.03b

Protein

17.41+0.04a

17.82+0.02a

18.11+0.03a

18.28+0.01b

18.33+0.02b

18.37+0.01b

Fat

1.72+0.03a

2.37+0.04b

2.62+0.03c

2.78+0.01c

2.71+0.02c

2.92+0.03c

Ash

1.24+0.3b

1.35+0.04b

1.33+0.03b

1.24+0.03b

0.86+0.02a

1.23+0.03b

3.92

4.18

4.32

4.40

4.44

4.48

Food conversion efficiency (%)

Net production (g/25m3/63 days) Carcass proximate composition (%)

Calorific value (kJ/g)

Values with different superscripts in the same row indicate significant (P≤0.05) difference




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