Effect of Organically Complexed Copper, Iron, Manganese, and Zinc ...

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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 ...

©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 Cooperative Research 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 resulted in a high level of mineral excretion that ends up in the environment. Organically complexed trace minerals (organic minerals) may be able to replace the inorganic trace minerals, because the former appear to have a greater bioavailability. Therefore, a 29-d cage study that included diets with supplemental trace minerals from organic and inorganic sources based on a trace mineral deficient control diet was conducted to examine the possible response of broiler chickens to organic mineral supplements. The results showed that supplementation with 4 mg of Cu and 40 mg each of Fe, Mn, and Zn from organic sources may be sufficient for normal broiler growth to 29 d of age. It is possible to use these lower levels of organic trace minerals in broiler diets to avoid high levels of trace mineral excretion. Key words: broiler, organic copper, iron, manganese, zinc, mineral excretion 2007 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 involved in many digestive, physiological, and biosynthetic processes within the body. They function primarily as catalysts in enzyme systems within cells or as parts of enzymes. They are also constituents of hundreds of proteins involved in intermediary metabolism, hormone secretion pathways, and immune defense systems [1]. Traditionally, these trace minerals are supplemented in the form of inorganic salts, such as sulfates, oxides, and carbonates, to provide levels of minerals that pre1

Corresponding author: [email protected]

vent clinical deficiencies, allow the bird to reach its genetic growth potential, or both. Despite enormous advances in poultry production and technology, research into trace mineral nutrition has lagged behind other areas of nutrition. In 2006, the BW of a meat chicken reached 2 kg in 35 d, down from 64 d in 1979. However, the trace mineral requirements for broilers have still been thought to be the same level as those recommended by the NRC in the early 1990s [2], some of which are based on data as far back as the 1950s. Although most of the increase in BW via genetic selection has been an indirect response to selection for appetite, in-

BAO ET AL.: RESPONSE OF BROILERS TO ORGANIC MINERALS creased body growth has resulted in skeletal problems, which may be related to poor mineral nutrition. It is thus reasonable to consider the current NRC recommendation as unsuitable for the needs of the modern bird. Actually, the industry is still using a large safety margin in feed formulation because of higher dietary mineral needs and cheaper cost of trace mineral sources. So, in commercial practice, these supplemental inorganic trace minerals result in a high level of mineral excretion. Obviously, this is not only wasteful but also harmful to the environment. For example, poultry manure applied on a N basis contains Zn and Cu, 660 and 560%, respectively, in excess of crop requirements [3]. Due to the concern for build-up of heavy metals when applying poultry litter to cropland, environmental protection agencies around the world have pressed for lower levels of mineral waste applied to land. Organically complexed trace minerals provide alternative pathways for absorption, thus leading to a reduction in the excretion of minerals [4, 5]. However, research into the use of organic trace mineral supplementations in broiler chicken diets is still at a nascent stage, and there are not enough data to determine optimal levels of supplementation and quantify differences in excretion rates between inorganic and organic sources. Most studies on organic minerals for broilers have used conventional diets, which makes it difficult to separate the effect of the supplemental minerals from that of native minerals in the ingredients [6, 7, 8, 9, 10, 11]. In addition, purified diets usually decrease feed intake of broilers and cannot support the bird to reach growth potential, leading to compromised growth of the chick due to deficiency of other nutrients [12]. The present study was conducted to evaluate a semiconventional control diet, based mainly on sorghum and isolated soy, to evaluate possible response of broilers 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 regarding animal care were approved by the University of New England Animal Ethics Committee (AEC 04/147).

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Animal Husbandry During the first 2 wk, 160 one-day-old Cobb broilers [13] (45.48 ± 1.61 g/bird) were randomly allocated to 40 multicompartment brooder units located in 2 temperature-controlled rooms, with 8 replicates (4 chicks in each cage) per dietary treatment. Each cage contained a water trough and a feeder. Room temperature was maintained at 34°C during the first 3 d and was gradually reduced to 28°C at the end of wk 2. Body weight and feed intake were recorded weekly. At 14 d of age, groups of 4 chicks were individually weighed and transferred to metabolism cages. After 4 d of adaptation period, all excreta were collected over 4 d and analyzed to evaluate excretion of trace minerals. At d 29, all birds were killed, and blood, liver, and right tibia were sampled to analyze for their mineral contents. Dietary Treatments The experimental design consisted of 5 treatments with 8 replicate cages per treatment. The dietary treatments were as follows: 1) control diet (Table 1) was formulated to either meet or exceed NRC [2] nutrient requirements, with the exception of Cu, Fe, Mn, and Zn, which were added to the experimental diets separately (Table 2); 2) organic 1 (LOW-ORG) was control diet supplemented 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 with 4 mg of Cu/kg of diet and 40 mg/kg of diet each of 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 (in sulfate form) per kilogram of diet. The organically complexed Cu, Fe, Mn, and Zn were provided as Bioplex-Cu, Bioplex-Fe, Bioplex-Mn, and Bioplex-Zn [14]. The vitamin-mineral premix [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 determine FCR, and both were corrected for mortality.

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450 Table 1. Composition of the control diet Ingredients

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

Amount, g/kg

Sorghum Isolated soy Vegetable oil Calcium carbonate Calcium phosphate NaCl Lys-HCl DL-Met Vitamin-mineral premix1 Choline chloride Total

771.0 175.0 16.00 12.46 18.20 2.50 1.00 2.34 1.00 0.50 1,000

Calculated nutrient analysis ME (kcal /kg) CP, % Ca, % Available P, % Lys, % Cu, mg/kg (as fed, analyzed) Fe, mg/kg (as fed, analyzed) Mn, mg/kg (as fed, analyzed) Zn, mg/kg (as fed, analyzed)

3,125 22.5 0.84 0.42 1.12 4.20 42.19 14.82 20.38

Chemical Analysis Feed samples were prepared for inductively coupled plasma emission spectroscopy (ICP) [17] by grinding them to pass through a 0.5-mm screen in a stainless blade grinder. After grinding, 0.5 g of samples was placed in a Teflon tetrafluroethylene 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 total volume with deionized water and mixed well for ICP analysis [18]. Fecal samples were prepared according to methods described by AOAC [19] and Dozier et al. [20] for ICP analysis. Tibia samples were boiled for approximately 10 min in deionized water and cleaned of all soft tissue. Tibia and liver samples were then dried and ashed for ICP analysis [21]. For measurement of Cu, Fe, Mn, and Zn contents in the plasma, 4 mL of plasma sample was wet-ashed in a beaker by adding 10 mL of nitric acid and heated to minimal volume (the solution was never allowed to dry). When the solution was cooled, it was filtered into a 25-mL flask and diluted to 25 mL with deionized water for ICP analysis.

1

Vitamin-mineral premix supplied the following per kilogram of diet: 10,000 IU of vitamin A, 2,500 IU of vitamin D3, 50 mg of vitamin E, 2 mg of thiamine, 10 mg of riboflavin, 50 mg of niacin, 7 mg of D-calcium pantothenate, 7 mg of pyridoxine, 25 ␮g of cyanocobolamin, 250 ␮g of biotin, 0.3 mg of Se, 1 mg of I, 0.5 mg of molybdenum, and 0.25 mg of Co.

Excreta Collection At 14 d of age, all chicks were weighed and transferred to metabolism cages. From 19 to 22 d of age, total excreta from each cage were collected daily and dried at 80°C in a forced draft oven. Fresh and dry weights of feces were recorded.

Statistical Analysis Statistical analyses were performed using STATGRAPHICS software [22]. The data were analyzed using 1-way ANOVA with diet as the factor. The significance of difference between

Tissue and Blood Sample Collection At termination of the experiment, all birds were killed, and blood samples were individually Table 2. Dietary treatments fed to broilers Diet1 Control Low organic Mid organic High organic Inorganic 1

Added Cu (mg/kg)

Added Fe (mg/kg)

Added Mn (mg/kg)

Added Zn (mg/kg)

0 2 4 8 5

0 20 40 80 70

0 20 40 80 80

0 20 40 80 50

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

BAO ET AL.: RESPONSE OF BROILERS TO ORGANIC MINERALS

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Table 3. Effect of different diets on feed intake, body growth, and FCR of broilers (0 to 29 d) Diet Control Low organic Mid organic High organic Inorganic Pooled SEM P-value

Intake, 0 to 7 d (g/bird)

Weight gain (g/bird)

Intake (g/bird)

147.6 146.9 145.6 151.0 154.6 4.95 0.70

979.9c 1,380.7b 1,499.5a 1,494.5a 1,481.9a 57.95

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