Dietary zinc requirement of fingerling Oreochromis niloticus

Dietary zinc requirement of fingerling Oreochromis niloticus

Aquaculture, 119 ( 1994) 259-264 Elsevier Science B.V., Amsterdam 259 AQUA 50125 Dietary zinc requirement of fingerling Oreochromis niloticus Abd...

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Aquaculture, 119 ( 1994) 259-264 Elsevier Science B.V., Amsterdam

259

AQUA 50125

Dietary zinc requirement

of fingerling

Oreochromis niloticus Abd. Elhamid Eid”,* and Samir Ibrahem Ghonimb ‘Department ofAnimal and Fish Production, Faculty OfAgriculture, Suez Canal University, Ismailia, Egypt bFish Research Center, Suez Canal University,Ismailia, Egypt (Accepted 3 September

1993)

ABSTRACT Fingerling Nile tilapia were fed puritied diets with and without supplemental zinc ranging from 0 to 100 mg Zn/kg diet for 70 days. Nile tilapia fed the basal diet containing 1 mg Zn/kg developed deficiency signs such as anorexia and poor growth. Fish fed the lowest levels of supplemental zinc (0 and 5 mg Zn/kg diet) had poor growth and high mortality, while the levels over 30 mg/kg showed reduced mortality and markedly improved growth. Dietary zinc levels were significantly correlated with whole-body zinc concentration. A strong negative correlation also observed between dietary zinc and whole-body iron. Weight gain percent, feed efficiency, serum zinc and bone zinc concentrations indicated that the minimum zinc requirement of fingerling Nile tilapia is 30 mg Zn/kg dry diet.

INTRODUCTION

Determination of the dietary mineral requirements of fish is complicated by the fact that minerals are not only available to fish from dietary sources but also from the surrounding water. The nutritional requirements of fish for dietary minerals have been reviewed by Mill&in ( 1982) and Lall ( 1989). Dietary zinc requirements have been quantitated for the rainbow trout (Ogino and Yang, 1978), common carp (Ogino and Yang, 1979), channel catfish (Gatlin and Wilson, 1983 ), blue tilapia (McClain and Gatlin, 1988 ) and Japanese eel (Won and Shimizu, 1989). Common zinc deficiency signs such as reduced growth rate and high mortality have been observed in rainbow trout (Ogino and Yang, 1978 ) , common carp (Ogino and Yang, 1979) and channel catfish (Gatlin and Wilson, 1983 ), whereas a high incidence of cataracts has been associated with zinc deficiency in rainbow trout (Ogino and Yang, 1978; Ketola, 1979 ) . Correspondence to: Dr. Abd. Elhamid Eid, Department of Animal and Fish Production, of Agriculture, Suez Canal University, Ismailia, Egypt.

SSDZ0044-8486(93)E0209-R

Faculty

260

A.E. EID AND S.I. GHONIM

The present study was conducted to investigate the dietary requirement of Nile tilapia (Oreochromis niloticus) for zinc. MATERIALS AND METHODS

Fish and rearing procedure Four hundred fingerling (0. niloticus) weighing 8.40 + 0.06 g were used. The fish were randomly divided into 10 groups of 20 fish in duplicate. The experiment was conducted in glass aquaria (80x 50x40 cm) each of 160 litres capacity. Each aquarium was filled with dechlorinated tap water and provided with supplemental aeration. Water temperature was maintained at 25 ? lo C throughout the experiment by automatic heaters. Compositionof the diets The basal diet (Table 1) was formulated from purified ingredients to contain 30% crude protein. Dietary ingredients were commercially obtained: egg white, cr-cellulose, corn starch (El Gamhoria Company), corn oil and cod liver oil (El Nile Company). Diets were prepared by adding graded levels of zinc (ZnSO,* 7H20) to the basal diet while removing corresponding amounts of cellulose. These supplemental zinc concentrations ranged from 0 to 100 mg/kg diet. The basal diet was analysed to contain 1 mg/kg, and supplemental zinc levels of other diets were contirmed by analysis using atomic absorption spectrometry (Model 2380, Perkin Elmer, USA). Prior to initiation of the experiment, the fish underwent a 2-week conditioning period during which they readily adjusted to a basal diet and standardized environmental conditions. Experimental diets were fed at a rate equaling 3% of fish wet weight per day. This amount of diet was divided into two equal feedings per day. Each group of fish was weighed every 10 days, and the amount of diet was adjusted accordingly. Fish were fed the test diets for 70 days. Methylene blue (4 mg/l) was added to the rearing water after weighing the fish to reduce bacterial infection caused by handling. The experimental diets were analysed for moisture, crude protein, ether extract, crude fiber and ash by standard AOAC methods (AOAC, 1980). The composition and proximate analysis of the basal diet are given in Table 1. Sample collectionand mineral analyses Blood samples were taken from all fish in each group 15-20 h after the final feeding. These samples were collected by severing the caudal peduncle. After exsanguination, IO carcasses from each group were frozen for subsequent bone mineral analyses. The blood samples were allowed to clot in tubes at room temperature and the serum removed. Serum samples were prepared for mineral analyses by atomic absorption spectrophotometry according to the method of Parker et al. (1967).

DIETARY ZINC REQUIREMENT

OF NILE TILAPIA

261

TABLE 1 Composition of the basal diet Ingredient

% dry weight

Egg white” Corn starch Corn oilb Cod liver oilb cr-Cellulose* Zinc-free mineral mix” Calcium carbonate Vitamin mix’ CMCd ADEK vitamin mix”

34 30 4 5 18 4 0.5 1 1 1

Proximate analysis Moisture Protein Lipid Ash Fiber NFE’ Zinc (ppm)

8.50 30.10 8.80 8.30 18.10 26.20 1.00

“From El Gamhoria Company, Egypt. bFrom El Nile Company, Egypt. ‘Same as Gatlin and Wilson ( 1983). dcarboxymethyl cellulose. “ADEK Vitamin premix (as g/kg): Retinyl acetate, 1.8; vitamin D3, 0.25; DLa-tocopheryl 2.25; Cod liver oil 990.7. PNitrogen Free Extract.

acetate,

Intact trunk and caudal vertebrae were removed from 10 pooled carcasses from each group for mineral analyses. The procedures for bone preparation and mineral analyses were as described by Gatlin et al. ( 1982).

Statistical methods Analysis of variance and Duncan’s multiple range test were carried out according to Snedecor and Cochran ( 1980). RESULTS AND DISCUSSION

The group of fish fed the basal diet began to exhibit anorexia after 40 days. Weight gain and feed efficiency data (Table 2 ) for tilapia fed the basal diet were significantly lower than those for tilapia fed diets containing supplemental zinc. There was a significant difference in weight gain and feed efficiency between fish fed the diet supplemented with 30 mg Zn/kg and all other experimental groups. Growth increased rapidly in all experimental fish, but the

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A.E. EID AND %I. GHONIM

TABLE 2 Performance of fingerling Nile tilapia fed diets with various zinc concentrations’ Supplemental zinc (mgkg)

Initial wt. (g)

Final wt. (g)

Weight* gain (86)

Feed’ efficiency

Mortality (%)

0 5 10 20 30 40 50 60 80 100

8.4 8.3 8.4 8.4 8.5 8.5 8.5 8.4 8.5 8.4

16.0’ 16.5’ 17.2” 18.0d 23.1” 19.1’ 21.1b 18.3* 18.7* 18.9*

90.47’ 98.79’ 104.76’ 1 14.28d 171.76” 124.70’ 148.23b 117.85* 120.00d 125.00cd

0.69” 0.75’ 0.83* 0.87’

10.0” 8.0b 3.0’ 2.0d 0.0’ 0.0’ 0.0’ 1.0” 2.0d 1.0’

1.20” 0.93”b 0.97b 0.90’b 0.90Cb 0.92”b

‘Means of two replicate groups. ‘Expressed as percent increase in initial body weight at the end of 70-day period. ‘Wet weight gain/ dry weight feed. 4Means in the same column not sharing a common superscript letter are significantly (P
different

zinc-deficient fish (diet 1) gained weight at less than half the rate of the fish fed the diet supplemented with 30 mg Zn/kg. During the experimental period, higher levels of dietary zinc did not appear to inhibit weight gain. Requirement studies in rainbow trout (Ogino and Yang, 1978 ), common carp (Ogino and Yang, 1979), channel catfish (Gatlin and Wilson, 1983) and blue tilapia (McClain and Gatlin, 1988 ) have yielded similar growth responses. The mortality rate (Table 2) of Nile tilapia fed the basal diet was significantly (PcO.05) higher than that of fish fed the other experimental diets. These deaths were attributed to zinc deficiency because of the absence of bacterial infections or other adverse environmental factors. Fish fed the other dietary zinc levels had either no or very low mortality, which did not appear to be related to dietary treatment. The previous studies, rainbow trout, common carp and channel catfish fingerlings fed 1 mg Zn/kg dry diet had poor growth and high mortality, whereas feeding 5 mg Zn/kg diet prevented significant mortality (Ogino and Yang, 1978, 1979; Gatlin and Wilson, 1983). In these three studies water zinc concentrations were 10, 11 and 25 ppb compared with 15 ppb in the present study with Nile tilapia. Differences in water zinc concentrations may have contributed to different mortality rates of common carp, rainbow trout and channel catfish fed the basal diets ( 1 mg Zn/ kg) in the previous studies. High mortality has usually been associated with zinc deficiency in fish (Ogino and Yang, 1978; Wekell et al., 1983). Wholebody zinc concentrations were significantly affected by dietary treatment (Table 3), in agreement with Hardy and Shearer ( 1985). Thus feeding low dietary zinc (diet 1) rendered tilapia deficient, using criteria of cessation of

263

DIETARY ZINC REQUIREMENT OF NILE TILAPIA

TABLE 3 Response of fingerling Nile tilapia fed diets with various zinc concentrations’ Supplemental zinc (mg/kg) 0

5 10 20 30 40 50 60 80 100

Serum zinc’ @g/d1 )

Bone zinc (Pg/g)2

Whole-body iron’ (M/g)

Whole-body zinc’ @g/g)

82P 146od 1780” 1890b 2700” 2740” 2800” 2880” 2820” 2790”

42.10” 75.20* 120.10= 18O.5Ob 235.10” 230.30” 240.40” 240.40” 238.10’ 242.2P

8O.lP 78.30b 75.40” 74.80* 74.20’ 73.60’ 72.90s 65.8Oh 60.70’ 60.10

40.10’ 45.20’ 52.20h 63.800 66.40’ 70.20” 73.20* 78.60” 80.20b 82.10“

‘Means of two replicate groups on dry basis. ‘Means in the same column not sharing a common (P
superscript

letter are significantly

different

growth, significant mortality and decreased serum and whole-body zinc. These responses are in agreement with Gatlin and Wilson ( 1983) and Spry et al. (1988). Dietary zinc levels were significantly (r=0.92; PcO.05) correlated with whole body zinc concentration, in agreement with Hardy and Shearer ( 1985 ) and Wekell and Shearer ( 1986). Analysis of serum zinc and bone zinc (Table 3) showed that these concentrations did not increase significantly after a supplemental zinc level of 30 mg/kg diet. These responses are in agreement with Gatlin and Wilson ( 1983 ) . Comparison of mean whole-body zinc concentrations from the 10 treatments and whole-body iron concentrations indicated a significant negative correlation (r=0.87; P
of Official Analytical

Chemists,

Offtcial Methods

of Analysis,

1 lth

264

A.E. EID AND S.I. GHONIM

Davis, G.K., 1980. Microelement interaction of zinc, copper and iron in mammalian species. In O.A. Lavander and L. Cheng (Editors), Microelement Interactions: Vitamins, Minerals and Hazardous Elements. New York Academy of Science, New York, pp. 130-l 37. Gatlin, D.M., III and Wilson, R.P., 1983. Dietary zinc requirement of fingerling channel catfish. J. Nutr., 113: 630-635. Gatlin, D.M., III, Robinson, E.H., Poe, W.E. and Wilson, R.P., 1982. Magnesium requirement of fingerling channel cattish and signs of magnesium deficiency. J. Nutr., 112: 1182- 1187. Hardy, R.W. and Shearer, K.D., 1985. Effect of dietary calcium phosphate and zinc supplementation of rainbow trout (Salmo gairdneri). Can. J. Fish. Aquat. Sci., 42: 18 1- 184. Ketola, H.G., 1979. Influence of dietary zinc on catracts in rainbow trout (Salmogairdneri). J. Nutr., 109: 965-969. Lall, S.P., 1989. The minerals. In: J.E. Halver (Editor), Fish Nutrition. Academic Press, Inc., New York, pp. 2 19-257. McClain, W.R. and Gatlin, D.M., III, 1988. Dietary zinc requirement of Oreochromis aureus and effect of dietary calcium and phytate on zinc bioavailability. J. World Aquacult. Sot., 19: 103-108. Millikin, K.R., 1982. Qualitative and quantitative nutrient requirements of fishes: a review. Fish. Bull., 80(4): 655-686. Ogino, C. and Yang, G.Y., 1978. Requirement of rainbow trout for dietary zinc. Bull. Jpn. Sot. Sci. Fish., 44: 1015-1018. Ogino, C. and Yang, G.Y., 1979. Requirement of carp for dietary zinc. Bull. Jpn. Sot. Sci. Fish., 45: 967-969. Parker, M.M., Humoller, F.L. and Mahler, D.J., 1967. Determination of copper and zinc in biological material. Clin. Chem., 13: 40-48. Settlemire, C.T. and Malrone, G., 1967. In vivo effect of zinc on iron turnover in rats and life span of the erythrocyte. J. Nutr., 92: 159- 164. Snedecor, G.W. and Cochran, W.G., 1980. Statistical Methods. Iowa State University Press, Ames, IO, pp. 143. Spry, D.J., Hodson, P.V. and Wood, C.M., 1988. Relative contribution of dietary and waterborne zinc in rainbow trout (Salmogairdneri). Can. J. Fish. Aquat. Sci., 45: 32-41. Wekell, J.C. and Shearer, J.D., 1986. Zinc supplementation of trout diets. Tissue indicators of body zinc status. Prog. Fish-Cult., 48: 205-2 12. Wekell, J.C., Shearer, K.D. and Houle, C.R., 1983. High zinc supplementation of rainbow trout diets. Prog. Fish-Cult., 45: 144-147. Won, P.C. and Shimizu, C., 1989. Suitable level of zinc supplementation to the formulated diets in young eel. Bull. Jpn. Sot. Sci. Fish., 55: 2137-2 141.