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Effects of Iron Glycine Chelate (Fe-Gly) on Broilers

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Published: Mon, 07 May 2018

Abstract

The objective of this study was to evaluate the effects of iron glycine chelate (Fe-Gly) on growth, immune organ indexes, and liver antioxidant enzyme activities in broilers. A total of 480 1-day-old Arbor Acres commercial broilers were randomly allotted to eight dietary treatment groups with six replications of ten chicks per replicate. Broilers were fed a control diet with 120mg/kg FeSO4, while seven other treatment groups consisted of 40, 60, 80, 100, 120, 140 and 160 mg Fe/kg diets from Fe-Gly. After a 21-day feeding trial, the results showed that 100 mg Fe/kg as Fe-Gly improved the average daily gain (P<0.05) and 80 and 100 mg/kg as Fe-Gly elevated average daily feed intake (P<0.05) of broilers. There were linear responses to the addition of Fe-Gly from 40 to 160 mg/kg Fe on thymus gland index, and addition of 160mg/kg treatment groups was significant increased (P<0.05), no significant differences on spleen index and Bursa of fabricius index could be observed between the treatments (P>0.05).Addition with 120 and 140 mg Fe/kg from Fe-Gly increased liver catalase activities (P<0.05), and superoxide dismutase activities of chicks were increased by the addition of 120, and 160 mg /kg Fe as Fe-Gly to diets. There were no differences in liver xanthine oxidase activities of chicks among the treatments (P>0.05). This study indicates that addition with Fe-Gly could improve growth performance, immune function and antioxidant status of broiler chickens.

Introduction

Iron (Fe) is an essential trace element that plays a vital role in various physiologic processes. Recently, the Fe supplement that primarily has been commonly used in chicken diets is the inorganic form. It was reported that metal chelated with amino acid or protein has good bioavailability in animal. A study showed that chelated or proteinated source of Fe had 125-185% relative availability compared with ferrous sulphate (1) and addition of Fe from iron chelated with amino acids or protein to the diet has can prevent and treat Fe deficiency in animals or humans (Veum et al., 1995; Spears et al., 1999; Bovell-Benjamin et al.,2000; Kegley et al., 2002; Feng et al., 2007). Research on pigs indicated that iron methionine had a higher bioavailability than ferrous sulphate in nursing pigs (Spears et al., 1992). Mortality, birth and weanling body weight of piglets were improved significantly when sows were fed with iron proteinate (Close, 1998, 1999). Yu et al. (2000) found iron from an amino acid complex increased plasma iron and total iron binding capacity in the blood, hemosiderin and ferritin iron in the liver and spleen of weanling pigs. It was established that iron chelated with glycine could be absorbed and utilized easily in rat and human, which could produce more effective results in prevention and treatment of iron deficiency than that of ferrous sulphate (Iost et al., 1998; Bovell-Benjamin et al., 2000; Oscar and Ashmead, 2001). Iron glycine chelate (Fe-Gly) is currently used as an efficient iron fortificant in human food, especially in infant food (Fox et al., 1998). Iron fortification is crucial for broilers because of increasing demand for iron due to the rapid increases in red blood cell volume and body mass. Recently, data considering the utilization of dietary Fe-Gly in chicken production are limited. Therefore, The aim of our study was to evaluate the efficacy of different levels of dietary supplemental Fe-Gly on the biological effect about growth performance, immune function, and antioxidant property in broiler chickens.

Materials and methods

Animals and experimental design

Four hundred and eighty Arbor Acres commercial male broilers, one day old, were weighed and allocated randomly to eight treatment groups, each of which included six replicates of ten birds. During the 21-day experiment, treatments consisted of: (1) 40mg Fe from Fe-Gly/kg diet; (2) 60mg Fe from Fe-Gly/kg diet;(3) 80mg Fe from Fe-Gly/kg diet; (4) 100mg Fe from Fe-Gly/kg diet; (5) 120mg Fe from Fe-Gly/kg diet; (6) 140mg Fe from Fe-Gly/kg diet; (7) 160 Fe from Fe-Gly/kg diet; (8) the control, 120mg Fe from ferrous sulphate (FeSO4)/kg diet.

Broilers were randomly placed in floor pens and nutrient levels of the diets were based on the National Research Council (13) recommended nutrient requirements of broiler chickens (Table 1). On day 0, 21 of the experiment trial, all weight and feed consumption were measured and calculated average daily feed intake (ADFI), average daily gain (ADG), and feed/gain ratio (F/G). At 21 days of age, broilers were deprived of feed for 12 h to slaughter per pen.

Table 1

Composition of basal diet

ingredient

g/kg

Compositiona

%

Maize

547.6

ME(MJ/kg)

12.62

Soyabean meal (430 g CP/kg)

348.6

Crude protein

21.53

Fish meal

35

Lysine

1.23

Soybean oil

36

calcium

0.33

Dicalcium phosphate

12

nonphytate phosphorus

0.46

Limestone

13

methionine + cysteine

0.87

D,L-methionine(99%)

1.6

   

Salt

3

   

Choline

1

   

Mineral mixtures

2

   

Vitamin premix

0.2

   

Data and samples collection

All the broilers were bled via cervical vein for plasma sample and then slaughtered and dissected by a trained team. Ten ml blood was collected from each bird into a non-heparinized vacutainer tube for HB concentration analysis. Another blood samples were centrifuged at 3000 rpm for 15min and then serum was stored at -20℃ until analysis.

Heart, part of liver, spleen, thymus and bursa of fabricius were collected through washing in tap water and stored at -20℃ until analysis. Another part of liver, duodenum were collected and snap-frozen in liquid nitrogen and stored at -80℃ until analysis of realtime fluores-cence quantitative PCR.

Measurement of immune organ index

Immune organ index was determined using a method by Lu et al (1996).

Immune index (g/kg) =immune organ weight/empty body weight.

Determination of liver antioxidant enzyme activities

The total Iron binding capacity(TIBC), the activities of catalase (CAT) and xanthine oxidase(XOD) in plasma were assayed using colorimetric methods with a spectrophotometer (Biomate 5, Thermo Electron Corporation, Rochester, NY, USA).

Statistical analysis

All statistical analyses were were analyzed by ANOVA as a randomized complete block design using the GLM procedures of SAS. Individual chicks were the experimental unit for all indices. A software program using LSD’s multiple range test to compare treatment means was applied. A P < 0.05 was considered statistically significant. Replicate was considered as the experimental unit for growth performance. The experimental unit was a bird for the other indices. Numbers (n) used for statistics are noted in the tables. All data were expressed as means ± SE.

Results

Growth performance

Table 2 displays the effects of Fe-Gly and ferrous sulphate supplementation on broiler performances. Comparing with the control fed with dietary FeSO4, ADG of birds significantly increased by supplementation of Fe-Gly at 100 mg/kg level (P<0.05), and ADFI of 80 and 100mg/kg treatment groups were significantly higher. In addition, no significant effect was observed on F/G among all the treatments (P>0.05).

Item

Fe-Glyb

FeSO4c

40d

60d

80d

100d

120d

140d

160d

120d

Initial wt(g)

45.83±0.89

44.45±1.44

44.58±1.28

45.64±1.39

46.08±1.12

46.91±1.17

47.08±1.17

46.22±1.06

Final wt(g)

672.25±8.58

680.73±7.53

703.92±16.95

680.45±12.14

685.03±8.12

688.82±15.27

685.75±14.22

673.22±11.63

ADG(g)

29.48±0.25d

30.30±0.19cd

31.51±0.41ab

32.33±0.25a

30.47±0.19bcd

30.55±0.30bcd

30.74±0.61bc

29.85±0.35cd

ADFI(g)

46.23±0.16c

47.65±1.14bc

48.33±0.18ab

49.32±.0.57a

48.76±0.10ab

48.79±0.13ab

48.15±.0.13ab

47.50±0.15bc

F/G

1.57±0.02

1.57±0.05

1.53±0.02

1.53±0.03

1.60±0.01

1.60±0.01

1.57±0.03

1.59±0.02

Immune organ index

The effects of different levels of iron as Fe-Gly on immune organs index are shown in Table 3. Thymus gland index increased linearly with the increasing dietary Fe-Gly levels, and reached a peak in 160 mg/kg Fe as Fe-Gly group, with a more significant increased in 160mg/kg supplemental Fe-Gly group (P<0.05) at the side of the control as 120 mg/kg FeSO4, No significant differences on spleen index and Bursa of fabricius index could be observed between the treatments (P>0.05).

item

Fe-Gly

FeSO4

 

40

60

80

100

120

140

160

120

Spleen

0.82±0.05

0.83±0.05

0.71±0.03

0.73±0.08

0.69±0.05

0.68±0.06

0.73±0.07

0.74±0.04

Thymus gland

2.80±0.06bc

2.58±0.12c

2.84±0.09bc

2.84±0.08bc

2.81±0.13bc

3.02±0.11ab

3.28±0.17a

2.88±0.12bc

Bursa of fabricius

2.77±0.07

2.37±0.25

2.54±0.19

3.04±0.30

2.33±0.16

2.52±0.14

2.27±0.16

2.33±0.20

Liver antioxidant enzyme activities

Table 4 shows the effects of Fe-Gly and ferrous sulphate supplementation on liver SOD, CAT, and XOD activities in broilers. Comparing with the control fed with dietary FeSO4, CAT of birds’ liver was significantly increased by supplementation of Fe-Gly at 120 and 140 mg/kg level (P<0.05), and the addition of 120mg/kg Fe-Gly significantly improved SOD (P<0.05). In addition, no significant effect was observed on XOD among all the treatments (P>0.05).

item

Fe-Gly

           

FeSO4

 

40

60

80

100

120

140

160

120

CAT(U/L)

9.33±0.33d

9.17±0.46ed

10.02±0.24cd

10.00±0.43cd

11.67±0.59ab

12.92±0.63a

11.00±0.52bc

10.03±0.87cd

XOD(U/L)

1.81±0.27

1.57±0.19

2.03±0.18

2.40±0.22

2.03±0.23

2.58±0.36

2.19±0.28

2.16±0.13

SOD(U/L)

1.81±0.27

1.57±0.19

2.03±0.18

2.40±0.22

2.03±0.23

2.58±0.36

2.19±0.28

2.16±0.13

Discussion

Chickens are sensitive to dietary Fe concentrations, and Fe deficiency is known to affect the development of the chick (Tako et al., 2010). Thus, supplementation of Fe with a large safety margin to meet the dietary needs of broilers is used. In the present study, broilers fed on Fe-Gly supplemented diets had better ADG and ADFI than birds fed on positive control (with ferrous sulphate) diet. Agreeing with our findings, Langini et al. [23] reported that the absorption of Fe was 30.9 % in weanling rats given infant formula labeled with [59Fe]glycine compared with 15.8 % with [59Fe]sulfate. Additionally, they found that the percentage of the label in the blood after 14 days was 21.8% for the glycine compound and 7.5% for the sulphate compound. Layrisse et al. (2000) reported that iron from the Fe-Gly was absorbed twice as much as that from FeSO4 in a breakfast meal based on maize flour. They were all established that Fe-Gly had higher bioavailability in animals than inorganic ferrous. In all the amino acids, glycine has the lowest molecular weight, which favors the stability of the chelate, protecting the ferrous ion from undesirable chemical reactions in the stomach and intestines which limit the absorption of Fe (Ashmead, 2001). In addition, Fe from Fe-Gly has lower prooxidant properties because diets supplemented with additional Fe had positive effects on feed conversion ratio (FCR) in broilers. Galdi et al. (1989) showed that there were lower losses of 20–30% of vitamins C and E and no losses of retinol in the iron glycine fortified formula, compared with losses (40–60%) of vitamins A, C and E in formulas fortified with ferrous sulphate. Therefore, higher absorption and lower prooxidant properties may be both contributed to the positive effects of Fe-Gly on performance in present study.

Studies suggested that Iron plays a very important role in maintaining human and animal’s immune functions (Brock, 1994; Oppenheimer, 2001). The development of immune organ reflects the immune ability of animals. The gain of immune organs’ weights mean that the immune system matures better, which suggests that the immune function of body is stronger. In present study, the thymus gland index has a linear increasing response to dietary Fe-Gly, and comparing with 120 mg/kg Fe from ferrous sulphate, a lower level of dietary Fe-Gly can reach the same effect, but the both had no impacts on spleen and bursa of fabricius index. Immune organs such as the spleen, thymus gland, and bursa of fabricius are important ones to maintain normal immune functions of the animal bodies. Iron could accelerate the development of immune organs and iron deficiency tends to cause thymic atrophy (Oppenheimer, 2001). The thymus gland index may more sensitive for the change of iron supplement presented here, which needs further study.

Iron is an essential micronutrient, but the continuous presence of an excessive intake of Fe could produce reactive oxygen species (ROS) [31, 32] which is thought to cause diseases. SOD, CAT and XOD are antioxidant enzymes considered as the indicators because they are involved in obliterating ROS directly. SOD converts the active oxygen groups to H2O2, and CAT is responsible for destructing the excess H2O2. XOD is a antioxidant enzyme accelerating the production of ROS. It has been shown that adding exogenous XOD to generate free radicals can damage muscle function in animal. In present study, it indicated that with the addition of Fe, the activity of CAT has a linear increase. This agrees with other studies performed in rats. Hallquist (1993) reported that CAT activity decreased significantly in rats liver when fed with iron deficiency, this suggested that Iron status influence the CAT activity significantly in vivo, and it was activated to restrain the activity of CAT when the iron deficiency. Brandsch et al. (2002) found that catalase activity in rat liver increased by feeding high iron diets, and they speculated it was because of increased iron concentrations in the liver rather than induction by oxidative stress. Increased SOD activity was observed when birds fed with 120,140 and 160mg/kg Fe as Fe-Gly in present study, Davis and Feng [35] found that dietary Fe (140 mg Fe/kg diet) caused a significantly increased SOD activity in rats. So we supposed that Fe-Gly had a better biological efficiency at the side of FeSO4, comparing with the control, more ROS was produced and the activity of SOD increased. XOD activity was not affected by Fe-Gly or FeSO4 addition in diet of broliers in present study. Feeding rats a wide range of dietary Fe up to 10 times the estimated requirement, did not induce overt oxidative stress (Roughead et al., 1999). This indicates that the moderately high intake of Fe in the present study may not pose a major risk in increasing oxidative stress in chicks, although this point needs further research. In summary, Fe-Gly is more effective in improving the antioxidant status than FeSO4 in broilers. These findings indicated that Fe-Gly improved antioxidative status of male broilers by elevating the activity of antioxidant enzymes and reducing the production of peroxidation.


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