©2007 Poultry Science Association, Inc.

Effect of Organically Complexed Copper, Iron,Manganese, and Zinc on Broiler Performance,

Mineral Excretion, and Accumulation in Tissues

Y. M. Bao,* M. Choct,† P. A. Iji,*1 and K. Bruerton‡

*School of Environmental and Rural Science, and †Australian Poultry CooperativeResearch Centre, University of New England, Armidale, New South Wales 2351,

Australia; and ‡Protea Park Nutrition, Palm Beach,Sorrento, Queensland 4217, Australia

Primary Audience: Nutritionists, Nutrition Researchers, Feeding Managers

SUMMARY

Supplementation of trace minerals with a large safety margin in broiler chickens has resultedin a high level of mineral excretion that ends up in the environment. Organically complexed traceminerals (organic minerals) may be able to replace the inorganic trace minerals, because theformer appear to have a greater bioavailability. Therefore, a 29-d cage study that included dietswith supplemental trace minerals from organic and inorganic sources based on a trace mineraldeficient control diet was conducted to examine the possible response of broiler chickens to organicmineral supplements. The results showed that supplementation with 4 mg of Cu and 40 mg eachof Fe, Mn, and Zn from organic sources may be sufficient for normal broiler growth to 29 d ofage. It is possible to use these lower levels of organic trace minerals in broiler diets to avoid highlevels of trace mineral excretion.

Key words: broiler, organic copper, iron, manganese, zinc, mineral excretion2007 J. Appl. Poult. Res. 16:448–455

DESCRIPTION OF PROBLEM

Trace minerals, such as Cu, Fe, Mn, and Zn,are essential for broiler growth and are involvedin many digestive, physiological, and biosyn-thetic processes within the body. They functionprimarily as catalysts in enzyme systems withincells or as parts of enzymes. They are also constit-uents of hundreds of proteins involved in interme-diary metabolism, hormone secretion pathways,and immune defense systems [1]. Traditionally,these trace minerals are supplemented in the formof inorganic salts, such as sulfates, oxides, andcarbonates, to provide levels of minerals that pre-

1Corresponding author: piji@une.edu.au

vent clinical deficiencies, allow the bird to reachits genetic growth potential, or both.

Despite enormous advances in poultry pro-duction and technology, research into trace min-eral nutrition has lagged behind other areas ofnutrition. In 2006, the BW of a meat chickenreached 2 kg in 35 d, down from 64 d in 1979.However, the trace mineral requirements forbroilers have still been thought to be the samelevel as those recommended by the NRC in theearly 1990s [2], some of which are based on dataas far back as the 1950s. Although most of theincrease in BW via genetic selection has been anindirect response to selection for appetite, in-

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creased body growth has resulted in skeletal prob-lems, which may be related to poor mineral nutri-tion. It is thus reasonable to consider the currentNRC recommendation as unsuitable for the needsof the modern bird.

Actually, the industry is still using a largesafety margin in feed formulation because ofhigher dietary mineral needs and cheaper cost oftrace mineral sources. So, in commercial practice,these supplemental inorganic trace minerals re-sult in a high level of mineral excretion. Obvi-ously, this is not only wasteful but also harmfulto the environment. For example, poultry manureapplied on a N basis contains Zn and Cu, 660and 560%, respectively, in excess of crop require-ments [3]. Due to the concern for build-up ofheavy metals when applying poultry litter to crop-land, environmental protection agencies aroundthe world have pressed for lower levels of mineralwaste applied to land. Organically complexedtrace minerals provide alternative pathways forabsorption, thus leading to a reduction in theexcretion of minerals [4, 5]. However, researchinto the use of organic trace mineral supplementa-tions in broiler chicken diets is still at a nascentstage, and there are not enough data to determineoptimal levels of supplementation and quantifydifferences in excretion rates between inorganicand organic sources.

Most studies on organic minerals for broilershave used conventional diets, which makes itdifficult to separate the effect of the supplementalminerals from that of native minerals in the ingre-dients [6, 7, 8, 9, 10, 11]. In addition, purifieddiets usually decrease feed intake of broilers andcannot support the bird to reach growth potential,leading to compromised growth of the chick dueto deficiency of other nutrients [12]. The presentstudy was conducted to evaluate a semiconven-tional control diet, based mainly on sorghum andisolated soy, to evaluate possible response ofbroilers to organically complexed Cu, Fe, Mn,and Zn in performance, trace mineral excretion,and tissue accumulation.

MATERIALS AND METHODS

All methods used in this experiment regard-ing animal care were approved by the Universityof New England Animal Ethics Committee (AEC04/147).

Animal Husbandry

During the first 2 wk, 160 one-day-old Cobbbroilers [13] (45.48 ± 1.61 g/bird) were randomlyallocated to 40 multicompartment brooder unitslocated in 2 temperature-controlled rooms, with8 replicates (4 chicks in each cage) per dietarytreatment. Each cage contained a water troughand a feeder. Room temperature was maintainedat 34°C during the first 3 d and was graduallyreduced to 28°C at the end of wk 2. Body weightand feed intake were recorded weekly. At 14d of age, groups of 4 chicks were individuallyweighed and transferred to metabolism cages.After 4 d of adaptation period, all excreta werecollected over 4 d and analyzed to evaluate excre-tion of trace minerals. At d 29, all birds werekilled, and blood, liver, and right tibia were sam-pled to analyze for their mineral contents.

Dietary Treatments

The experimental design consisted of 5 treat-ments with 8 replicate cages per treatment. Thedietary treatments were as follows: 1) control diet(Table 1) was formulated to either meet or exceedNRC [2] nutrient requirements, with the excep-tion of Cu, Fe, Mn, and Zn, which were addedto the experimental diets separately (Table 2); 2)organic 1 (LOW-ORG) was control diet supple-mented with 2 mg of Cu/kg of diet and 20 mg/kg of diet each of Fe, Mn, and Zn; 3) organic 2(MID-ORG) was control diet supplemented with4 mg of Cu/kg of diet and 40 mg/kg of diet eachof Fe, Mn, and Zn; 4) organic 3 (HIGH-ORG)was control diet supplemented with 8 mg of Cu/kg of diet and 80 mg/kg of diet each of Fe,Mn, and Zn; and 5) inorganic positive control(INORG) was supplemented with 5 mg of Cu,70 mg of Fe, 80 mg of Mn, and 50 mg of Zn (insulfate form) per kilogram of diet. The organi-cally complexed Cu, Fe, Mn, and Zn were pro-vided as Bioplex-Cu, Bioplex-Fe, Bioplex-Mn,and Bioplex-Zn [14]. The vitamin-mineral pre-mix [15] was free of Cu, Fe, Mn, and Zn.

Measurements

Birds were weighed individually at the start,then weekly and at the end of the experiment.Feed intake in each cage was recorded to deter-mine FCR, and both were corrected for mortality.

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Table 1. Composition of the control diet

Ingredients Amount, g/kg

Sorghum 771.0Isolated soy 175.0Vegetable oil 16.00Calcium carbonate 12.46Calcium phosphate 18.20NaCl 2.50Lys-HCl 1.00DL-Met 2.34Vitamin-mineral premix1 1.00Choline chloride 0.50Total 1,000

Calculated nutrient analysisME (kcal /kg) 3,125CP, % 22.5Ca, % 0.84Available P, % 0.42Lys, % 1.12Cu, mg/kg (as fed, analyzed) 4.20Fe, mg/kg (as fed, analyzed) 42.19Mn, mg/kg (as fed, analyzed) 14.82Zn, mg/kg (as fed, analyzed) 20.38

1Vitamin-mineral premix supplied the following perkilogram of diet: 10,000 IU of vitamin A, 2,500 IU ofvitamin D3, 50 mg of vitamin E, 2 mg of thiamine, 10 mgof riboflavin, 50 mg of niacin, 7 mg of D-calciumpantothenate, 7 mg of pyridoxine, 25 �g of cyanocobolamin,250 �g of biotin, 0.3 mg of Se, 1 mg of I, 0.5 mg ofmolybdenum, and 0.25 mg of Co.

Excreta Collection

At 14 d of age, all chicks were weighed andtransferred to metabolism cages. From 19 to 22d of age, total excreta from each cage were col-lected daily and dried at 80°C in a forced draftoven. Fresh and dry weights of feces were re-corded.

Tissue and Blood Sample Collection

At termination of the experiment, all birdswere killed, and blood samples were individually

Table 2. Dietary treatments fed to broilers

Added Cu Added Fe Added Mn Added ZnDiet1 (mg/kg) (mg/kg) (mg/kg) (mg/kg)

Control 0 0 0 0Low organic 2 20 20 20Mid organic 4 40 40 40High organic 8 80 80 80Inorganic 5 70 80 50

1Low-, mid-, and high-organic diets and inorganic diets were based on the control diet.

collected into heparinized tubes. The tubes werethen centrifuged at 1,000 × g for 15 min [16],and the supernatant was transferred to 5-mL tubesand frozen at −20°C. The right tibia from eachbird was pooled per cage and then frozen foranalysis. The liver from 1 bird in each cage wasweighed and frozen for analysis.

Chemical Analysis

Feed samples were prepared for inductivelycoupled plasma emission spectroscopy (ICP)[17] by grinding them to pass through a 0.5-mmscreen in a stainless blade grinder. After grinding,0.5 g of samples was placed in a Teflon tetraflur-oethylene vessel. Eight mL of nitric acid (70%)was added along with 2 mL of hydrogen peroxide(30%). The solution was made to 50 mL of totalvolume with deionized water and mixed well forICP analysis [18]. Fecal samples were preparedaccording to methods described by AOAC [19]and Dozier et al. [20] for ICP analysis.

Tibia samples were boiled for approximately10 min in deionized water and cleaned of all softtissue. Tibia and liver samples were then driedand ashed for ICP analysis [21].

For measurement of Cu, Fe, Mn, and Zn con-tents in the plasma, 4 mL of plasma sample waswet-ashed in a beaker by adding 10 mL of nitricacid and heated to minimal volume (the solutionwas never allowed to dry). When the solutionwas cooled, it was filtered into a 25-mL flaskand diluted to 25 mL with deionized water forICP analysis.

Statistical Analysis

Statistical analyses were performed usingSTATGRAPHICS software [22]. The data wereanalyzed using 1-way ANOVA with diet as thefactor. The significance of difference between

BAO ET AL.: RESPONSE OF BROILERS TO ORGANIC MINERALS 451

Table 3. Effect of different diets on feed intake, body growth, and FCR of broilers (0 to 29 d)

Intake, 0 to 7 d Weight gain Intake FCRDiet (g/bird) (g/bird) (g/bird) (intake/gain)

Control 147.6 979.9c 1,567.5b 1.590 ± 0.093a

Low organic 146.9 1,380.7b 2,077.1a 1.510 ± 0.094b

Mid organic 145.6 1,499.5a 2,100.3a 1.403 ± 0.067c

High organic 151.0 1,494.5a 2,137.4a 1.432 ± 0.052bc

Inorganic 154.6 1,481.9a 2,210.0a 1.493 ± 0.069b

Pooled SEM 4.95 57.95 37.37 0.027P-value 0.70 <0.001 <0.001 <0.001

a–cMeans within a column with unlike superscripts differ significantly (P < 0.05).

means was determined by Duncan’s multiple-range test. Regression analysis was carried outonly with control diet and different levels of or-ganic treatments.

RESULTS AND DISCUSSION

Broiler Performance

During wk 1, there was no significant differ-ence in feed intake between the control and exper-imental groups (Table 3). After 1 wk, the birdson the control diet started to show symptomsof mineral deficiencies, including reduced feedintake and consequently reduced body growth.Supplemental Cu, Fe, Mn, and Zn, regardless oftheir source, improved (P < 0.01) broiler perfor-mance. The organic supplements had positive ef-fects on live weight gain and FCR, but there wasno significant difference (P > 0.05) in BW gainbetween organic trace minerals and the positive(inorganic) control. The MID-ORG diet achieveda superior (P < 0.01) FCR than the inorganicpositive control due to relatively less feed intakeby the MID-ORG treatment. However, there wasno additional response in growth and FCR forthe HIGH-ORG diet.

The control diet had Cu, Fn, Mn, and Znbelow NRC requirements for broilers. Therefore,the birds on the control diet grew poorly butsurvived for the entire experimental period. Thedeficiency of Cu, Fe, Mn, and Zn in the controldiet strongly affected feed intake, which led todepressed growth of broilers. This is similar tothe symptom of Zn deficiency described by Kinget al. [23] that a marked reduction in dietary Znis invariably followed quickly by a reduction infood intake and growth failure. The mechanismsinvolved in the effects of deficiency of Zn ongrowth are unknown, but a reduction in food

intake may be a protective response to ensuresurvival and maintain relatively normal, albeitdownregulated, metabolic levels of these miner-als [24]. The birds on the MID-ORG diet reachedoptimal BW gain and were 53% heavier than thebirds fed the control diet. However, HIGH-ORGtreatment with the highest supplemental levels ofthe 4 minerals, which was close to the commercialrecommendation of the minerals, did not showany further response in weight gain and FCR.So, it may not be necessary to supplement theseorganically complexed minerals at levels as highas those currently used by industry.

Mineral Excretion

The excretion of Cu, Mn, and Zn increased(P < 0.001) linearly with increasing intakes ofthese trace minerals (Table 4). Thus, the birds onthe MID-ORG diet, which supported the bestFCR, had a lower (P < 0.001) trace mineral excre-tion than those on the HIGH-ORG treatments.This clearly suggests that the highest levels oforganically complexed Cu, Mn, and Zn tested inthe current study do not contribute to bird growthbut are excreted. Indeed, it is well known thatchanges in trace mineral absorption and excretionin the gastrointestinal tract are primary mecha-nisms for maintaining trace mineral homeostasis[23]. Due to this pattern of excretion, the apparentabsorption of Cu, Fe, Mn, and Zn is not suitableto assess the bioavailability of trace minerals [25].A pronounced reduction in Zn and Cu excretioncould only be achieved by dietary manipulation[20, 26]. The current experiment demonstratedthat the highest organic trace mineral supplemen-tation had no additional effects on broiler perfor-mance, and it is possible to use lower levels oforganic trace mineral supplements without com-

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Table 4. Trace mineral excretion in birds fed different diets (mg/bird per d; 18 to 21 d)

Diet Cu Fe Mn Zn

Control 0.28d 17.66b 1.34d 2.30d

Low organic 0.56c 17.05b 3.85c 4.44c

Mid organic 0.83b 24.74b 6.22b 6.47b

High organic 1.22a 30.27ab 10.12a 10.91a

Inorganic 0.86b 46.66a 8.92a 11.05a

Pooled SEM 0.047 7.143 0.425 0.547P-value <0.001 0.039 <0.001 <0.001Regression to intake (R2) 90.61 7.22 90.28 88.38P-value <0.001 <0.140 <0.001 <0.001

a–dMeans within a column with unlike superscripts differ significantly (P < 0.05).

promising bird growth or increasing the rate ofexcretion.

Mineral Concentrations in Tibia

Table 5 shows that only the concentrationsof Zn in tibia increased (P < 0.001) linearly withZn intake. The Cu and Mn concentrations werealso increased (P < 0.001) with supplementaldietary Cu and Mn, but there was no significantdifference (P > 0.05) among supplemental or-ganic levels. There was no significant difference(P > 0.05) in tibia Fe concentration betweentreatments.

It has been observed that when the dietaryZn content was greater than the requirement forgrowth, there was an increase in the plasma andtibia concentration until a dietary concentrationof 48 mg of Zn/kg of diet was reached [26, 27].In the current experiment, tibia Zn concentrationswere also strongly related to the dietary organicZn intake (R2 = 70.28%), but the tibia Zn concen-tration reached a plateau as birds attained optimalBW on the diet in which the dietary Zn concentra-tion was 60 mg/kg of diet. The bone is a complex

Table 5. Trace mineral concentration of tibia bone of broiler chickens at 29 d of age (�g/g of dry bone)

Diet Cu Fe Mn Zn

Control 2.96b 54.65 2.64c 61.91d

Low organic 4.81a 69.38 3.61b 97.72c

Mid organic 5.90a 67.46 3.56b 139.73b

High organic 5.94a 65.68 4.16ab 148.91ab

Inorganic 6.37a 66.62 4.47a 160.16a

Pooled SEM 0.57 4.55 0.22 5.56P-value <0.001 0.183 <0.001 <0.001Regression to intake (R2) 17.30 5.21 39.02 70.28Regression to weight gain (R2) 60.35 5.60 24.22 62.08

a–dMeans within a column with unlike superscripts differ significantly (P < 0.001).

heterogeneous tissue that supports the muscula-ture, and, thus, its growth and development areintimately connected with overall body growth[28], making tibia Zn concentration a good pre-dictor of whole-body growth.

Mineral Concentrations in Liver and Plasma

At 29 d of age, the BW of birds fed the controldiet was only 70% that of birds on supplementaltreatments, but there was no significant difference(P > 0.05) in plasma trace mineral concentrations(Figure 1). Trace mineral concentrations in theliver of birds on the control diet were higher (P< 0.05) than those on the supplemental treat-ments, but there was no significant difference (P> 0.05) among different supplemental treatments(Figure 2).

That chickens give priorities to their mineralrequirements for vital functions in compromiseof body growth is indicated by the normal con-centrations of the minerals in the plasma of thecontrol birds. The concentrations of the trace min-erals were higher in the liver of birds on thecontrol diet than in those on the supplemented

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Figure 1. Concentrations of Cu, Fe, Mn, and Zn in the plasma of chickens on different diets (means ± SD).

diets. Similar findings have been attributed to adiluting effect as a result of rapid growth rate onthe adequate diets and poor growth rate on thecontrol diet [29]. With Zn, the results are consis-tent with the model for laboratory animals [30],which shows that if dietary deficiency of Zn ismild, the animal usually reduces the rate of

Figure 2. Concentrations (�g/g of dry tissue) of Cu, Fe, Mn, and Zn in the liver of chickens on different diets(means ± SD).

growth and excretion to maintain normal tissueconcentrations. This response is because an ani-mal at a stage of development at which sensitivityto Zn deficiency is high stops growing immedi-ately when given a low-Zn diet, but it maintainsa normal concentration of Zn in its tissues [31].It indicates that the assessment of trace mineral

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status is difficult and remains an important, trickychallenge. This result is also in agreement withhuman Zn research in which there appears to bean adaptation to low-Zn intake associated with a

CONCLUSIONS AND APPLICATIONS

1. The control diet based on natural ingredients produced marked trace mineral deficiencies. Whenthe broiler diet is deficient in trace minerals, birds will decrease their feed intake, resulting inpoor growth. It is necessary to supplement trace minerals in broiler diets to allow the modernbroiler to reach its genetic potential.

2. At lower supplemental levels, the organically complexed trace minerals were adequate to supportoptimum broiler chicken performance at reasonable rates of excretion.

REFERENCES AND NOTES

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4. Leeson, S. 2003. A new look at trace mineral nutrition ofpoultry: Can we reduce the environmental burden of poultry manure?Pages 125–129 in Nutritional Biotechnology in the Feed and FoodIndustries. Proc. Alltech’s 19th Annu. Symp. T. P. Lyons and K. A.Jacques, ed. Nottingham Univ. Press, Nottingham, UK.

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18. The vessel was closed and introduced to the rotor segmentand then tightened using a torque wrench. The segment was insertedinto the microwave cavity, and the temperature sensor was connected.The microwave program was run for 45 min. The rotor was cooledby air until the solution reached room temperature. The vessel wasopened, and the solution was quantitatively transferred into a 50-mLvolumetric flask.

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21. The samples were then dried for 12 h at 105°C. Liver sampleswere thawed and rinsed with deionized water and dried for 12 h at105°C. The liver and bone samples were then ashed (550°C for 4 h).Approximately 1 g of ash samples was then dissolved in 10 mL of3M hydrochloric acid and boiled for 10 min. The samples were allowedto cool and filtered into a 100-mL flask. It was diluted to 100 mLwith deionized water and analysed for Cu, Fe, Mn, and Zn.

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