Optimum dietary protein level for growth of bighead carp (Aristichthys nobilis) fry in a static water system

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Aquaculture, 93 (1991) 155-165 Elsevier Science Publishers B.V., Amsterdam

Optimum dietary protein level for growth of bighead carp (Aristichthys nobilis) fry in a static water system Corazon B. Santiago and Ofelia S. Reyes SEAFDECAquaculture Department, Binangonan Freshwater Station, Binangonan, Rizal, Philippines (Accepted 5 July 1990)

ABSTRACT Santiago, C.B. and Reyes, O.S., 199 1. Optimum dietary protein level for growth of bighead carp (Aristichthysnobilis) fry in a static water system. Aquaculture, 93: 155-165. Isocaloric diets (290 kcal digestible energy/ 100 g) with protein levels ranging from 20 to 50% in increments of 5% were fed to bighead carp fry (3.8 f 0.2 mg mean body weight and 9.8 f 0.1 mm total length) for 7 weeks. Growth in weight and length increased as the protein level of the diet increased from 20 to 30% and decreased as the protein level increased further. Although not significantly different (P>0.05) from those of fry fed the 25% or 35% protein diet, weight gain (250 mg) and increase in total length ( 15.7 mm) were highest for fry fed the 30% protein diet. Feed conversion ratio, protein efficiency ratio and survival rate did not clearly indicate the required protein level. The protein requirement was determined using a static-water culture system but assessment of the water quality failed to indicate an association between ammonia concentration and protein in the diet. Further research is necessary to determine why high levels of protein resulted in depressed growth.

INTRODUCTION

Among the Chinese carps, the bighead carp (Aristichthys nobilis) has become a favored species for culture in the Philippines (Fermin, 1988 ). A shortage of natural food, particularly Bruchionus and other small-sized zooplankton, is one constraint in the mass production of fingerlings for stocking in cages or ponds. Consequently, high-protein lishmeal-based practical diets have been developed and tested in feeding trials (Carlos, 1988; Fermin and Recometa, 1988; Santiago and Reyes, 1989 ) with the presumption that young bighead carp which feed mainly on zooplankton in natural environments require a high level of dietary protein of animal origin. Information on the protein requirements of various carp species such as common carp (Cyprinus curpio - Ogino and Saito, 1970; Sen et al., 1978; Takeuchi et al., 1979)) grass carp (Ctenopharyngodon idella - Dabrowski, 1977) and the Indian major carps ( CatZa catZaand Labeo rohita - Sir@ and 0044-8486 /9 l/$03.50

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Bhanot, 1988; Sen et al., 1978 ) is available but very little is known about the nutrient requirements of the bighead carp. The present study was conducted to determine the optimum level of dietary protein required by bighead carp fry for growth. MATERIALS AND METHODS

Experimental diets Seven isocaloric diets (290 kcal digestible energy/ 100 g ) containing varying levels of dietary protein (20, 25, 30, 35, 40, 45 and 50%) were formulated. Digestible energy values of 3.5, 8.1 and 2.5 kcal/g protein, lipid and carbohydrate, respectively, were used (NRC, 1977). Nutrient sources included fish meal, cod liver oil, corn oil, dextrin, and vitamin and mineral premixes (Table 1) . The vitamin and mineral supplements were designed to equal or exceed the amounts reported for common carp or recommended for warmwater fishes in general (NRC, 1977,1983 ). Calcium phosphate (monobasic) was added primarily to supply available phosphorus. The diets also contained Celufil, a non-nutritive filler, and carboxymethyl cellulose (CMC ), a binder. The dry ingredients were mixed thoroughly in a Hobart food mixer. The oils and finally water (400 ml/kg diet) were then added. The moist mixture was pelleted in a heavy-duty food grinder, oven-dried at 70°C until moisture content was about lo%, crumbled in a grinder and hand-sieved to obtain feed particles 5 250 pm. Diets were analysed for proximate composition (Lovell, 1975 ) and the results are presented in Table 1. Treatments,feeding and sampling There were seven dietary treatments, representing protein levels, with four replicates each in a completely randomized design. Twenty-eight glass aquaria with adequate aeration systems were used. Each aquarium (60 x 30 x 30 cm ), filled with 40 1 of aerated well water, was stocked with 200 bighead carp fry (mean initial weight = 3.8 2 0.2 mg, total length= 9.8 + 0.1 mm). The fry were fed three times daily with their respective test diets for 7 weeks at feeding rates slightly above satiation level ( 100% decreasing gradually to 20% of the fish biomass). Ten fish per aquarium were sampled at weekly intervals for growth measurements and for feed adjustment. Fish mortalities were recorded daily to estimate weekly survival rates. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were also estimated. Due to difficulties encountered in determining the unconsumed feed of the fry, the amount of feed given was presumed to be the amount consumed. Upon termination of the experiment, 60 fish per aquarium were sampled and final survival rates were determined.

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OPTIMUM DIETARY PROTEIN FOR GROWTH OF BIGHEAD CARP

TABLE I Composition carp fry

of diets (g/100 g diet) containing

varying levels of dietary protein fed to the bighead

Diet no. 1 Ingredient Fish meal Dextrin Cod liver oil Calcium phosphate (monobasic ) Filler (Celufil ) Others’

2

4

3

7

6

5

32.58 53.40 2.87 1.65

40.72 45.66 2.33 1.46

48.87 38.05 1.80 1.26

57.01 30.46 1.27 1.06

65.16 22.86 0.73 0.86

73.30 15.28 0.20 0.67

81.45 6.61 0 0.47

0 9.5

0.34 9.5

0.52 9.5

0.70 9.5

0.87 9.5

1.05 9.5

1.97 9.5

Estimated crude protein (%) 20 Estimated digestible energy 290 (kcal/lOOg)* Proximate analysis (% dry matter basis) Crude protein 23.1 Crude fat 6.3 Crude fiber 1.2 Ash 6.5 NFE (by difference) 62.9

25 290

28.0 8.3 1.4 7.8 54.4

30 290

33.2 8.2 1.6 8.8 48.2

35 290

38.0 9.5 1.5 9.9 41.1

40 290

43.3 8.4

45 290

47.2 8.3

50 290

54.8 6.7

1.7

2.2

2.1

11.4 35.2

13.3 29.0

12.4 23.4

‘Corn oil, 5.00%; vitamin premix, 1.50%; mineral premix, 1.21%; and binder (carboxymethyl cellulose), 1.79%. The vitamin premix was added to provide per kg diet: thiamin, 20 mg; riboflavin, 20 mg; pyridoxine, 20 mg; pantothenic acid, 50 mg; nicotinic acid, 50 mg; biotin, 0.1 mg; folic acid, 10 mg; vit. B,,, 0.2 mg; choline, 4 g; inositol, 0.5 g; vit. C, 1.O g; vit. A, 10 000 IU; vit. D, 2000 IU; vit. E, 0.3 g; vit. K, 20 mg; BHT, 2 mg; and tiller. The mineral premix was added to provide per kg diet: MgSO,*7H,O, 4.068 g; KIO,, 3.4 mg; ZnS04*7H20, 88 mg; CuS0,*5H20, 11.8 mg; MnS04.H,0, 36.9 mg; NaCl, 7.5 g; FeS04-7H20, 0.4 g. ‘Adopted from values for channel catfish: 3.5 kcal/g protein, 8.1 kcal/g fat, and 2.5 kcal/g carbohydrate (NRC, 1977).

Proximate composition of pooled fish samples for each treatment were analysed for moisture, crude protein, crude fat and ash.

Water management Aquaria were cleaned once or twice daily by siphoning feces and/or excess feeds with the use of plastic air tubing (4 mm inside diameter) and gently scrubbing the aquarium walls. One-half to two-thirds of the water was replaced after each cleaning. Water was completely changed during weekly sampling of fish. Water temperature, recorded twice daily at 07.30 and 13.30 h, ranged from 26 to 32 oC. Monitored before water was changed in the morning during weekly samplings, unionized ammonia ranged from 0.4 to 44.8 pg/l, pH from 6.9 to

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158

8.6 and dissolved oxygen, 4.2-6.9 mg/l. Water quality during each sampling did not differ significantly among treatments. Statisticalanalysis Data on body weight, total length, survival rate, FCR, PER and whole body composition were subjected to one-way analysis of variance. Differences in treatment means were compared by Duncan’s new multiple range test (cr=O.O5). Data on weight gain were also analysed using the quadratic or second-order polynomial regression analysis (Zeitoun et al., 1976 ) . RESULTS

The body weights of the bighead carp fry started to differ significantly (PC 0.05 ) among treatments after 3 weeks of feeding. Mean body weight after 7 weeks increased slightly as the protein level in the diet increased from 20 to 25%, but it increased significantly (PC 0.05 ) when the dietary protein further increased to 30% (Table 2). While the mean body weights of fish fed the 25 and 35% protein diets were lower, they did not differ significantly from that of fry fed the 30% protein diet. The regression curve showed that maximum growth response could be attained at the dietary protein level of 30.1% (Fig. 1), which is very close to the level determined by Duncan’s multiple range test. A significant growth depression was evident in fish fed the 40, 45 and 50% protein diets. The trend in mean total lengths of the fry closely followed that of the body weights (Table 2). TABLE

2

Mean body weight, total length, protein efficiency ratio (PER), feed conversion survival rate of bighead carp fed varying levels of dietary protein for 7 weeks’

ratio (FCR) and

Dietary protein (%)

Body weight + s.e. (mg)

Total length f s.e. (mm)

PER*

FCR’

Survival rate (%)

20 25 30 35 40 45 50

181 f22r’= 226 AI17sb 254f 1 la 206 + 27’b 189+27bc 144f 19” 135f 1oc

23.6? l.Osb 24.7kO.8” 25.5?0.4a 24.1 f 0.8” 23.5f0.2sb 21.5kO.7’ 22.0 f o.4bc

1.5” 1.6” 1.58 0.9b 0.7& 0.5” 0.4”

3.4bc 2.6’ 2.8” 2.8’ 3.8& 4.3Pb 5.0”

50”.” 57 55 55 56 52 48

MSE (d.f.)

1304.929 (21)

1.648 (21)

0.0300 (21)

0.5338 (21)

‘Initial mean body weight was 3.8f0.2 mg; total length was 9.820.1 mm. Column means with a common superscript are not significantly different (Pz 0.05). Differences in mean survival rates are not significant (n.s.). ‘PER=g weight gain/g protein fed. ‘FCR=g feed given/g weight gain.

OPTIMUM DIETARY PROTEIN FOR GROWTH OF BIGHEAD CARP

159

.

Y

1

20

I

30

I

I

40

50

DIETARY PROTEIN WoJ

Fig. 1. Relation between weight gain ( Y) and protein level (X) for bighead carp fry as described by quadratic regression. Regression model is Y= -25.675+ R2=0.50.

16.418X-0.273X2

N=28.

Fish fed the 25,30 and 35% protein diets had the best FCR (Table 2). The PER tended to decrease as the dietary protein level increased. mean survival rates did not differ significantly (P> 0.05 ) among treatments and mortalities were not treatment-related (Table 2 ). The whole body moisture content of the bighead carp fry was directly related to the increasing levels of dietary protein (rz0.86). Linear regression of moisture content on dietary protein level was significant (P
160

C.B. SANTIAGO AND OS. REYES

TABLE 3 Whole body composition of dietary protein’

of bighead carp after 7 weeks of feeding with diets containing varying levels

Dietary protein (%)

Moisture (Oh)

20 25 30 35 40 45 50

As percentage of dry matter*

78.0d 78.1d 78.5’ 79.8b 78.6’ 79.6b 80.1”

Crude protein

Crude fat

Ash

53.9b 56.7” 58.9” 59. la 58.3” 58.4a 57.4a

35.2” 30.6” 28.2” 29.9” 30.0” 29.7” 30.1”

9.8b 9.8b 9.9b 10.4a 10.Ob 10.5” 9.8b

‘Column means with a common superscript are not significantly different (P> 0.05). *At the start of the experiment, body composition of bighead carp fry on a dry matter basis was: crude protein, 63.4%; crude fat, 22.1%; ash, 13.1% (B. Acosta, personal communication, 1988).

q

crude protein

@

crude fat

1

ash

35 DIETARY PROTEIN

45

50

(o/o)

Fig. 2. Dry matter composition of bighead carp fry (mg/fish) varying protein levels.

after 7 weeks of feeding diets with

DISCUSSION

The 30% dietary protein was the optimum level for maximum growth of the young bighead carp. This is a relatively low level compared with the protein requirements reported for other carp species, particularly common carp fry, 45% (Sen et al., 1978) and fingerlings, 38% (Ogino and Saito, 1970);

OPTIMUM DIETARY PROTEIN FOR GROWTH OF BIGHEAD CARP

161

grass carp fry, 4 l-43% (Dabrowski, 1977 ); rohu fry, 45% (Sen et al., 1978 ); and catla fry, 47% (Singh and Bhanot, 1988). However, it is practically the same as that reported for the fry of walking catfish, C/arias batruchus (Chuapoehuk, 1987) and is near the values reported for common carp fingerlings, 31-32% (Takeuchi et al., 1979) and the fingerlings of carp tawes, Puntius gonionotus, 35% (Wee and Ngamsnae, 1987). Aside from species differences, the lower dietary protein requirement of the bighead carp could also be partly due to the high feeding rates and the protein source used in the present study. The young of several other warmwater fish species such as Tilupia zillii (Mazid et al., 1979); Nile tilapia, Oreochromisniloticus (Santiago et al., 1982; De Silva and Perera, 1985; Wang et al., 1985; Siddiqui et al., 1988); milkfish, Chaws chaws (Lim et al., 1979); and grey mullet Mugil cupito (Papaparaskeva-Papoutsoglou and Alexis, 1986) manifested growth depression in response to excessive levels of dietary protein when approximately isocaloric diets were tested. A similar growth response was reported for the fry of two species of cattish, Clarias batrachus and Pangasius sutchi, fed practical diets (Chuapoehuk and Pothisoong, 1985; Chuapoehuk, 1987). These fish species were reared in static systems with water changed regularly (Lim et al., 1979; Santiago et al., 1982; Chuapoehuk and Pothisoong, 1985; Chuapoehuk, 1987)) in water recycled through activated charcoal or a gravel-charcoal filter (Mazid et al., 1979; De Silva and Perera, 1985; Papaparaskeva-Papoutsoglou and Alexis, 1986) or in a flow-through system (Siddiqui et al., 1988). The growth of juvenile Sarotherodon mossambicus ( = 0. mussambicus) reared in a warmwater recycling system using diets with both increasing protein and energy levels decreased significantly at protein levels exceeding the requirement (Jauncey, 1982). Weight gain of hybrid tilapia (0. niloticus~ 0. aureus) reared in a recirculating water system increased with increasing protein level up to 48% and then decreased, but weight gains did not differ significantly at 24-56% dietary protein (Shiau and Huang, 1989). At each energy level tested, weight gain of red drum (Sciaenops ocellatus) reared in a recirculating system increased as the dietary protein level increased from 35 to 45% and then decreased when the protein level was further increased to 5 5% (Daniels and Robinson, 1986 ) . Protein levels greater than the requirement lowered the weight gains of the young of three species of carp (Sen et al., 1978; Wee and Ngamsnae, 1987; Singh and Bhanot, 1988 ) which were reared in a static-water (Sen et al., 1978) or in a recirculating system (Wee and Ngamsnae, 1987). On the other hand, percentage weight gain of grass carp reared in a running-water system increased with the dietary protein up to a level for maximum growth and then decreased as the protein level further increased (Dabrowski, 1977)) but for common carp in running water, growth increased with the increasing dietary protein (Ogino and Saito, 1970).

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Weight gain of the puffer fish (Fugu rubripes) reared in tanks with running water increased with dietary protein (casein) up to 50%, leveled off at 5559% protein and decreased at 75-809/o protein (Kanazawa et al., 1980). Average weight of Tilupia aurea fed diets with different protein levels (32-56%) and protein to energy (P/E) ratios increased with the increase of P/E ratio up to 108 mg/kcal (protein levels, 32-42%) and then decreased at the higher P/E ratios (protein levels, 43-56%) after 11 weeks of feeding in tanks with constant water flow (Winfree and Stickney, 198 1). Specific growth rates of the smallmouth bass (Micropterus ddomieui) and largemouth bass (M. Salmodes), in tanks with running water, increased with the dietary protein up to the minimum requirements and then leveled off (Anderson et al., 198 I). However, weight gains of fingerling walleyes (Stizostedion vitreum ), also reared in a running-water system, invariably increased with increasing dietary protein (37-5 1%) and then decreased at the higher protein level at three energy levels tested (Barrows et al., 1988). Hence, results of the studies on various fish species grown in different rearing systems show that extremely high dietary protein levels may depress growth. Excessive dietary protein (40-50%) caused a significant decrease in growth of bighead carp fry. This growth response could be attributed to insufficient non-protein energy in the high-protein diets which caused part of the dietary protein to be metabolized and used for energy (NRC, 1977 ) . The estimated digestible energy (DE) to protein ratio of the 30% protein diet which produced the highest weight gain for bighead carp fry was 9.7 kcal DE/g protein. This is very near the optimum DE/protein ratio of 10 kcal DE/g protein reported for common carp fingerlings (Murai et al., 1985 ). The DE/protein ratios for the 35,40, 45 and 50% protein diets were 7.2, 6.4 and 5.8, respectively. These values are low compared not only to the optimum DE/protein ratio reported for common carp but also for channel cattish which ranged from 8.7 to 9.7 kcal/g protein (Page and Andrews, 1973; Prather and Lovell, 1973; Garling and Wilson, 1977). When a diet is deficient in energy in relation to protein, dietary protein will be used for energy because energy needs for maintenance and voluntary activity must be satisfied first before energy becomes available for growth (Lovell, 1989). The use of protein as an energy source may cause high concentrations of nitrogenous wastes such as ammonia in the culture system. Higher production of ammonia might be considered more serious in experiments using staticwater systems. However, in the present study, unionized ammonia (NH3) levels fluctuated and there was no consistent trend of higher NH3 concentration in aquaria assigned higher dietary protein levels probably due to daily water changes. The linear regression of NH3 levels on dietary protein levels was not significant (P>O.O5, r*=0.058). Although percentage moisture content of the fish carcass increased with the dietary protein level, changes in fat and ash contents as % of dry matter were

OPTIMUM DIETARY PROTEIN FOR GROWTH OF BIGHEAD CARP

163

not clearly related to the dietary treatments. However, the amount of carcass fat (mg/fish) tended to decrease with increasing protein level in the diets. Moreover, the pattern of changes of carcass protein (mg/fish ) as influenced by the dietary protein level paralleled that of weight gain which indicates that growth was due mainly to an increase in body protein. In Yamato carp lingerlings fed diets with three protein levels and three levels of lipid at each protein level, there were no significant changes in carcass protein content but carcass lipid level increased with the increase of dietary lipid and decrease of dietary protein (Murai et al., 1985 ). The fat content of grass carp fry increased while protein and ash did not follow a definite trend when the dietary protein increased (Dabrowski, 1977 ). Gain in body protein of common carp increased with the dietary protein up to the optimum level of 38% and then leveled off (Ogino and Saito, 1970). In hybrid tilapia and 0. mossumbicus, gross body composition was not greatly affected by increasing protein levels but the fish tended to have lower body protein and higher body lipid content when fed low-protein diets (Jauncey, 1982; Shiau and Huang, 1989). For T. zillii lingerlings fed isocaloric diets, the lipid content tended to decrease while the ash content tended to increase as the protein level of the diet increased (Mazid et al., 1979). Because the amount of feed given was presumed to be the amount consumed by the fish, the FCRs were generally poor (overestimated). In effect, the PER for each treatment was actually slightly underestimated since the amount of protein fed was based on the assumed feed consumption. Nevertheless, the FCRs and the PERs in the present study were much better than those reported for catla fry (Singh and Bhanot, 1988) and, except for the fish fed high-protein diets, were near the values reported for carp tawes (Wee and Ngamsnae, 1987). However, the PER values obtained for common carp (Ogino and Saito, 1970; Takeuchi et al., 1979) were much higher than those obtained for the bighead carp. Survival rates were generally low but comparable to those reported earlier for young bighead carp under laboratory conditions (Carlos, 1988; Fermin and Recometa, 1988; Santiago and Reyes, 1989). Mean survival rates of 63, 59 and 29% have also been reported for bighead carp post-larvae (6-7 mm in length) at stocking densities of 476, 57 1 and 667 fish/m2, respectively, after 2 1 days of rearing in cement cisterns (2 1 m2) with fertilization and supplemental feeding ( Ariyarathana, 1986). The survival rates, FCR and PER were not indicative of the optimum protein level for bighead carp fry. However, data on growth in weight and in length invariably showed that the 30% dietary protein was required for maximum growth under the present experimental conditions. In the light of the present findings, the fishmeal-based practical diets currently used for bighead carp fry stand modification.

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ACKNOWLEDGMENT

We thank Mr. Renato Arcilla for the figures.

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