Pertanika 3(2), 71-77 (1980)

Effects of Zinc. Iron and Copper Supplementation inCassava-Based Diets for Broiler Chickens

C. H. PHUAH1 and R. I. HUTAGALUNGDepartment of Animal Sciences, Faculty of Veterinary Medicine and Animal Science,

Universiti Pertanian Malaysia, Serdang, Selangor, Malaysia

Key words: Zinc, iron and copper supplementation; cassava-based diets; broiler chickens; Malaysia

RINGKASAN

Dua percubaan yang melibatkan 216 ay am daging telah dijalankan untuk mengkaji pengaruh dariberbagai paras-paras zink (0, 25, 50 ppm) digabungkan dengan ferrum (0, 25, 50 ppm) di Percubaan 1 dandengan kuprum (0, 5, 10 ppm) di Percubaan 2, dalam ransum mengandung ubi kayu (40%) dan protein(20-17%). Ransum perlakuan telah disusun mengikut 3 X 3 faktorial percubaan. Penambahan mineralpada ransum asas ubi kayu tidak mempengaruhi kadar dan kecekapan kenaikan berat tubuh. Pemasukandari zink digabungkan dengan ferrum, atau kuprum tidak mempengaruhi kandungan lemak dan protein karkas.Ayam daging yang diberikan ransum-asas ubi kayu ditambahi dengan ferrum menurunkan paras zink, tetapimeninggikan kandungan zink hati dibandingkan dengan ransum-ransum yang tidak ditambahi dengan ferrum.Penaikan kandungan zink dari ransum mengurangi retensi zink hati samada penggabungannya dengan ferrumdan kuprum.

SUMMARY

Two experiments involving 216 chicks were conducted to assess the effects of supplemental levels of zinc(0, 25, 50 ppm) in combination with iron (0, 25, 50 ppm) in Experiment 1 and with copper (0, 5, 10 ppm)in Experiment 2, in diets containing cassava (40%) and protein (20-17%).. The dietary treatments werearranged in a 3 x 3 factorial experiment. Mineral supplementation in cassava-based diets had little overalleffect on rate and efficiency of gain. Inclusion of increasing amounts of zinc in combination with iron or copperhad inconsistent effects on fat and protein content of the carcass. Chicks fed cassava-based diets supplementedwith iron showed less carcass zinc levels, but had higher liver zinc content than those fed diets unsupplementedwith iron. Raising the zinc content of the diet resulted in reducing copper retention in the liver, regardlessof its combination with iron and copper.

INTRODUCTION

Hutagalung et al. (1973) showed that pigsfed diets containing 60-75% cassava root deve-loped disorders such as diarrhoea, skin lesionsin the stomach and hind quarters, localizedswelling and hind leg weakness. The diarrhoeasymptom was also observed in poultry (Fraser,1973). Maust et al (1969, 1972) attributed thedisorders developed in animals fed cassava-baseddiet to a zinc deficiency (parakeratosis). Zinc isreported to antagonize copper absorption, reten-tion and distribution in the body (Magee andMatrone, 1960; Ritchie et al, 1963; Van Campen,1966; Van Campen and Scaife, 1967). A signi-

ficant antagonism between iron and copper isalso reported (Anthony and Nix, 1965; Sourkeset al, 1968, Standish et al, 1969). Zinc andiron supplementation tends to reduce coppertoxicity (De Goey et al, 1971), as molybde-num does (Kline et al, 1971).

In view of the close interrelationships amongcopper, iron and zinc, the following experimentswere carried out to investigate the effects of thesetrace elements supplementation above the normalrequirements on the performance, and on thecarcass characteristics of broiler chicks fed dietscontaining a high proportion of cassava.

1 Present address: Yew Lee Feed Mill Sdn. Bhd., 4, Jalan 241, Petaling Jaya, Selangor, Malaysia, formerly atAnimal Production Research Division, Malaysian Agricultural Research and Development Institute, Serdang,Selangor, Malaysia.

71

C. H. PHUAH AND R. I. HUTAGALUNG

MATERIALS AND METHODS

Two experiments were conducted usingtwo-week-old broiler chicks (Red Cornish XWhite Plymouth Rock) fed starter (20% protein)and grower (17% protein) diets containing 40%cassava root meal. These were arranged in a3 x 3 factorial experiment to study the effectsof graded levels of supplementation of: (1) zinc(0, 25, 50 ppm) and iron (0, 25, 50 ppm) inExperiment 1; and (2) zinc (0, 25, 50 ppm) andcopper (0, 5, 10 ppm) in Experiment 2. Fourchicks of uniform mean weight were randomlyallotted to each of the three replicates of the ninedietary treatments.

Water and feeds were provided ad libitum.Individual body weight and group feed con-sumption were recorded weekly. The diets werechanged from the starter to grower dietswhen the chicks reached the age of six weeks.The experiments were carried out for a periodof 56 days. The compositions of the diets aregiven in Table 1. Supplemental zinc, iron and

TABLE 1Composition of basal diets

Ingredients, %

Cassava root mealCornSoybean mealFish mealPalm oilTricalcium phosphateSaltMineral mixture1

Vitamin premix2

DL-MethionineL-LysineKaolin

Total

Calculated constituents

Protein (N x 6.25), %Metabolizable energy, kcal/gCalcium, %Phosphorus, %Zinc, ppmIron, ppmCopper, ppm

Diets

Starter

40.0016.2520.6016.204.001.450.500.300.100.200.100.30

100.00

20.023.011.831.00

59.90144.8023.27

Grower

40.0022.2517.8012.005.001.450.500.300.100.200.100.30

100.00

16.993.051.740.90

54.18135.1821.98

iContributed the following per kg diet: Fe, 59.06 mg;Cu, 13.39 mg; Mn, 82.75 mg; Zn, 33.75 mg;Co, 2.73 mg; I, 1.41 mg and Mg, 560 mg.

Contributed the following per kg of diet: Vitamin A,50,000 IU; Vitamin D, 10,000 IU; Vitamin E,12.50 IU; riboflavin, 15 mg; thiamine, 5 mg;vitamin 65, 250 mg; pantothenic acid, 25 mg;niacin, 404 mg; vitamin B12, 20 mg; choline1008 mg.

copper were added as zinc sulphate (ZnSO4.7H2O), ferrous sulphate (FeSO4.7H2O) andcopper sulphate (CuSO4.5H2O), respectively, inplace of kaolin.

At the end of the trials, three birds fromeach treatment (one from each replicate) whichhad been deprived of rations for 12 hours, werekilled with chloroform. The whole carcasses ofthe birds were frozen, cut into sections andgrouped. Samples were taken for moisture,protein and fat analyes following proceduresdescribed in A.O.A.C. (1970). In addition, threemore birds from each treatment were slaughteredfor their livers. Samples of livers and wholecarcasses were analyzed for zinc, iron and copperby acid digestion procedure (Perkin-Elmer, 1971).

The data from all experiments were statisti-cally analyzed by the variance method as describedby Steel and torrie (1960). Significant differ-ences between means were compared using theleast significant difference (LSW) test.

RESULTSExperiment 1Performance. Incorporation of graded levels ofzinc and iron in diet did not significantly affectdaily gain, feed intake or feed conversion ratio;nor was there significant zinc X iron interactionfor these criteria (Table 2).

Body composition. Increased dietary intake ofiron significantly (P<0.01) reduced the carcassprotein content in a linear trend. The carcassprotein, however, was not affected by an increasein zinc intake. In regard to the iron X zincinteractive effect, increased dietary zinc wasfound to reduce carcass protein content whenbirds were fed low-iron (no supplementation)diets but increased when fed the high-iron(50 ppm iron supplementation) diets.

Carcass fat content in the body was signi-ficantly (P<0.01) influenced by supplementationof zinc and iron. Increasing zinc supplemen-tation to 25 ppm in diet decreased the carcassfat content; however, a further increase to 50 ppmproduced a restoring effect. The reverse wastrue with iron supplementation where anincrease in iron supplementation to 25 ppmraised body fat content; but a further 50 ppmincrease lowered the fat content. A zinc Xiron interaction effect on fat deposition was alsoobserved. An increase in iron supplement from0 to 25 ppm in diets supplemented with up to25 ppm zinc increased fat deposition but

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SUPPLEMENTATION IN CASSAVA-BASED DIETS FOR BROILERS

Effects of

Zinc addition, ppm

Iron addition, ppm

Avg diet intake1, g/day

Avg daily gain1, g

Feed/gain1

Whole carcass7:

Protein*. 5 f %

Fat3.5, %

Zinc-'*5, pprn

Iron^.S, ppm

Copper1, ppm

Liver7:

Zinc3.6t ppm

Iron3>5, ppm

Copper^*5, ppm

TABLE 2

zinc and iron supplementationbody composition of

0

56.33

17.22

3.27

58.69

33.31

163.30

239.60

13.00

169.52

518.55

34.40

0

25

52.93

16.74

3.16

54.42

36.08

168.40

255.60

9.90

166.67

542.20

32.84

50

58.33

17.53

3.33

52.28

38.94

167.60

273.10

9.20

173.30

592.20

36.64

in cassava-based diets on performance andchicks (Experiment 1)

Dietary variables

0

51.04

15.71

3.25

56.30

33.10

193.20

252.60

9.20

184.23

520.01

24.27

25

25

49.64

15.67

3.17

52.05

35.87

167.60

276.10

11.60

189.47

558.44

28.12

50

56.42

18.37

3.07

54.55

31.05

186.10

313.40

8.40

188.57

610.36

26.00

0

51.24

18.37

3.08

53.46

37.21

238.10

233.20

9.20

192.54

618.46

19.27

50

25

48.85

16.18

3.02

57.56

37.77

173.00

273.80

8.50

194.34

662.75

17.44

50

47.76

14.83

3.22

55.07

33.51

172.80

314.00

9.80

200.44

727.60

17.04

!Not significant at (P<0.05)Significant at (P<0.01) for iron in a linear trend but not for zinc^Significant at (P<0.01) for both iron and zinc in quadratic trends^Significant at (P<0.01) for zinc in a linear trend but not for iron5Significant at (P<0.01) for iron x zinc interactionSignificant at (P<005) for iron X zinc interaction7Protein, fat, zinc, iron and copper values were based on the dry matter of samples

lowered fat deposition in diets supplementedwith 50 ppm zinc.

Tissue mineral composition. The zinc depositedin tissues reflected the level of dietary zinc(Table 2). There was a significant zinc X ironinteraction effect on the carcass zinc content(P<0.01). The increased zinc content in dietimproved the zinc status in the liver of birds feddiets containing supplemented iron (25 and50 ppm); the increase was more pronounced inbirds fed diets containing a lower level of ironsupplementation (0 and 25 ppm). Overall, thediets supplemented with 25 and 50 ppm ironappeared to reduce the zinc content of carcassbut slightly improved zinc retention in liver.

The iron deposited in tissues also reflectedthe level of dietary iron. Carcass and liver zinccontent was significantly (P<0.01) influencedby zinc X iron interaction. Increased dietary

zinc intake raised carcass iron content only upto 25 ppm zinc supplementation; above thisvalue, the carcass iron concentration was reduced.The increase in liver iron content continuedeven at 50 ppm zinc supplementation. Iron incarcass was raised by increased dietary ironintake. High zinc and high iron diets enhancediron retention in liver.

Copper content in carcass was not signi-ficantly affected by both zinc and iron supple-mentation. Liver copper was linearly (P<0.01)lowered by the increased dietary zinc intake,but not by iron intake. There was a markedzinc x iron interaction (P<0.01) effect on livercopper retention. Increased zinc supplemen-tation, regardless of dietary iron, reduced livercopper content; the reduction however, was moresubstantial in the high-iron (50 ppm supple-mentation) diets.

73

C. H. PHUAH AND R. I. HUTAGALUNG

Experiment 2Performance. Average daily gain, feed intake orfeed conversion ratios were not significantlyaffected by feeding graded levels of zinc andcopper; nor were there significant zinc X ironinteraction for these criteria (Table 3).

Body composition. The protein and fat contentof carcass were significantly (P<0.01) influencedby feeding varied levels of zinc and copper;however, the response to zinc showed a quadratictrend, whereas, for copper, it was linear (Table 3).Increased zinc supplementation to 25 ppmincreased the average carcass protein contentfrom 56.23 to 61.15%, but a further additionof zinc up to 50 ppm did not increase the carcassprotein. Dietary copper depressed the carcassprotein content only up to 5 ppm supplemen-tation; at 10 ppm copper supplementation therewas no further depression. There was also a

zinc X copper interaction (P<0.01) effect onthe protein values. Copper supplementation upto 5 ppm in diet significantly (P<0.01) increasedthe carcass protein content at low-zinc (0 to25 ppm supplementation) diet; however, whencopper was increased to 10 ppm, a reductionin the protein content was observed. Theaddition of 5 ppm copper to the diet con-taining 50 ppm zinc reduced the carcass proteincontent but this was restored by increasing thecopper additive to 10 ppm.

The effect of dietary zinc on fat depositionwas inconsistent. Supplementation of 25 ppmzinc in the diet reduced fat content, but a furtheraddition had a restoring effect. Increased dietaryintake of copper raised the carcass fat value(P<0.01). Theie was also a significant (P<0.01)zinc x copper interaction effect on the carcassfat content. The greater intake of copper

Effects zinc

Zinc addition, ppm

Copper addition, ppm

Avg diet intake1, g/day

Avg daily gain1, g

Feed/gain1

Whole carcass10:

Protein*,8, %

Fat2,8, %

Zinc3, ppm

Iron**,8, ppm

Copper5,9, ppm

Liver?:

Zinc6,8, ppm

Iron7,8, ppm

Copper2,8, ppm

TABLE 3and copper supplementation in cassava-based diets on performance

body composition of chicks (Experiment 2)

0

56.12

17.32

3.25

55.93

29.20

194.80

309.70

11.80

166.83

585.90

30.59

0

5

48.35

16.35

2.96

58.09

21.58

211.90

287.80

14.80

159.27

547.48

73.66

10

57.14

18.69

3.08

54.68

27.73

225.10

246.60

17.70

155.09

582.35

126.28

Dietary variables

0

49.26

17-70

2.78

62.30

21.64

228.60

258.40

10.40

171.26

516.73

23.43

25

5

52.07

18.16

2.88

61.25

27.79

228.60

318.00

13.60

168.58

585.09

55.53

10

51.01

17.66

2.90

59.89

22.94

187.60

306.00

17.90

173.65

557.65

73.43

0

56.80

19.94

2.84

60.53

23.55

231.80

323.60

13.10

185.15

559.43

21.00

and

50

5

49.30

17.63

2.80

56.87

27.50

212.40

313.20

15.90

203.58

600.79

51.64

10

55.96

19.87

2.82

59.86

28.64

164.80

294.60

10.70

204.57

551.14

68.52

iNot significant at (P<0.05)2Significant at (P<0.01) for zinc in a quadratic trend but for copper in a linear trend^Significant at (P<0.05) for copper in a quadratic trend but not for zinc^Significant at (P<0.05) for zinc in a linear trend but not for copper^Significant at (P<0.05) for zinc in a quadratic trend but for copper in a linear trendSignificant at (P<0.05) for zinc in a quadratic trend but not for copperSignificant at (P<0.01) for both zinc and copper in quadratic trend8Significant at (P<0.01) for copper-zinc interaction9Not significant at (P<0.05) for copper-zinc interaction

10Protein, fat, zinc, iron and copper values were based on the dry matter of samples

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SUPPLEMENTATION IN CASSAVA-BASED DIETS FOR BROILERS

appeared to reduce fat deposition in birds whichhad been fed on 0 and 25 ppm zinc-supplementeddiets, but fat content was markedly increasedby additional copper intake when the diet wassupplemented with 50 ppm zinc.

Tissue mineral composition. Supplementation ofcopper at 5 ppm did not significantly affect thecarcass zinc content. On increasing the dietarycopper supplementation, however, to 10 ppm,the carcass zinc content was significantly (P<0.01)reduced (Table 3). Iron content in carcass wasnot affected by copper supplementation butcopper content in the carcass increased linearly(P<0.01) as the dietary copper was raised.A zinc X copper interactive effect on carcasszinc and iron was observed although the trendof the response was not consistent. Coppercontent in the carcass was not influenced by thezinc X copper interaction.

A zinc X copper interaction effect on liverzinc content was observed. Increased dietarycopper when added to diets with no zinc supple-mentation reduced liver zinc but its depressingeffect was reduced as a higher level of zinc wasincorporated into the diets. Considering overalleffects, liver zinc content was significantly(P<0.01) increased by zinc supplementation.

Liver iron content was markedly (P<0.01)affected by both dietary zinc and copper intake,although the effect was not linear. Dietarysupplementation of 25 ppm zinc resulted in areduction in liver iron, but when supplemen-tation was doubled the liver iron content wasrestored to that found in the unfortified diet.Copper addition at 5 ppm increased iron retentionin the liver (554 to 578 ppm) but the addition ofa further 10 ppm copper restored the ironretention in the liver to the level obtaining incases when copper was supplemented at 10 ppm.A significant interaction between zinc and copperon the liver iron content was also noted. In-creasing copper supplementation, in the low-zinc diet increased liver iron content, but anadverse response was observed when copper wasadded to high-zinc diet.

Liver copper content was significantly(P<0.01) reduced by supplementation of 25and 50 ppm zinc in diets. On the other hand,copper supplementation increased the liver con-tent linearly (P<0.01). A zinc X copper inter-action (P<0.01) effect on liver copper was alsoobserved.

DISCUSSION

Supplementation of zinc, iron and copperin cassava-based diets did not show significanteffects on the daily gain, food intake and feedconversion efficiency of the broiler chicken. Acomparison of the requirement of zinc, iron andcopper (N.R.C. 1971) with their content in thediets reveals that these elements were adequateeven in the unsupplemented diets (Table 1).Since there were no cases of toxicity observed,dietary zinc, iron and copper leveled up to104 ppm (basal + 50 ppm zinc), 185 ppm(basal + 50 ppm iron) and 32 ppm (basal +10 ppm copper), respectively, could be safetygiven to the broilers.

Earlier studies on the addition of zinc todiets found that zinc additives tend to reducefeed intake and gain in poultry (Underwood,1971) and on lambs (Ott et al, 1966). Theseworkers ascribed the depressing effects to theunpalatability of the high-zinc diet. Such obser-vations, however, were not apparent in thepresent study. The reason could be that theamount of ZnSO4 . 7H2O used in the presentstudy was not large enough to affect the tasteof the rations.

With cassava-based diets, supplementationof zinc had been reported to improve growth(Hutagalung et aL, 1973; Maust et al, 1969,1972). Maust et al. (1972) postulated that factorspresent in the cassava-based diet decreased thebiological availability of the dietary zinc. Supple-mentation with inorganic zinc helps to replenishthe zinc that was reduced in the cassava-baseddiets. The extent to which the zinc is madeunavailable by the cassava factors is not known,Judging from the results obtained in this study,the additional amount of zinc required to upsetthis factor is not great; it is estimated to be inthe region of a 10 ppm zinc addition to the normalrequirement.

The factors that reduced the zinc availabilityfrom a cassava-based diet could probably berelated to other ingredients used in the diet.Since cassava root meal is very low in protein(about 1.5%), the amount of soybean meal andfish meal had to be proportionally raised tobalance the dietary protein as a larger quantityof cassava is used in the diet. This could leadto reduced absorbability of zinc from the intestinedue to the presence of phytic acid from soybeanas reported by Savage et al. (1964). Additionalfish meal introduced into the diets would raise

75

C. H. PHUAH AND R. I. HUTAGALUNG

the dietary calcium level since fish meal is veryrich in calcium (about 7.0%). Calcium aggra-vates zinc depletion in the intestine by raisingthe intestinal pH (O'Dell, 1969). Combinationof these two factors would reduce the zinc avail-ability. Hence, the addition of zinc into diet ininorganic form provides a substitute wherebyzinc is made use of for normal body function.

The results obtained are in agreement withthe finding that poultry response to coppersupplementation in diet shows no improvementin growth (Coates and Harrison, 1959; Slingeret aL, 1962) or that the response is too smallto be statistically significant (Smith, 1969). Therelationship between copper supplementationand the nature of basal diet was studied byJenkins et aL (1970). Copper supplementationat 250 ppm improved growth in diets containingwheat and tallow but depressed growth in maizediets. It appears that a similar interactionbetween copper supplementation and cassavadiet might affect the performance of chicks.However, on the basis of this study, there is noevidence which could substantially support thisspeculation.

The effect of the supplementation of zinc,iron and copper on carcass fat and protein con-tent was inconsistent. The relationship betweenmineral and protein or fat deposition in the bodyis not clear. In the present study, carcass proteincontent maintained an inverse relation with thecarcass fat suggesting that probably zinc, ironand copper supplementation had no direct effecton the degree of protein and fat accumulationin the body.

Tissue studies show that the quantity ofmineral deposited was correspondingly pro-portionate to that supplemented in the diet.Liver was found to be very susceptible to coppersupplementation in that high dietary coppersubstantially increased liver copper accumu-lation.

The degree to which reduction of copperoccurs in the liver of chicks when the diet wassupplemented with dietary zinc is in agreementwith earlier reports (Magee and Matrone, 1960;Ritchie et aL, 1963; Van Campen, 1966; VanCampen and Scaife, 1967) indicating that zincantagonizes copper absorption and retention inthe body. Starcher (1969) suggested that thedepressing effect of zinc on copper absorptionin chicks arises from the fact that this elementbinds to and displaces copper from a duodenalmucosa protein resulting in reduced absorbabilityof copper into the system.

From a commercial standpoint growthperformance is the main criterion that deter-mines profitability. In the present study, weightgain was not improved by mineral supplemen-tation. It can then be concluded that withcassava root constituting meal up to 40% of thediet, the fortification of specific mineral elementsis not necessary. However, this may not betrue when cassava root meal constitutes a greaterproportion of the broiler feed or when it is usedto completely replace maize as an energy source.

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(Received 30 July 1979)

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