Effects of organic iron with different ligands on production performance of weaned piglets

A feeding trial using weaned piglets of lacking iron was conducted to determine the effects of different ligand organic iron on the growth performance. Compared with the control (FeSO4), ferrous glycine, ferrous fumarate can improve the ADG and the appearance, reduce the FCR, among which ferrous glycine is better; but the lysine iron, ferrous methionine have the opposite effect; organic iron tend to reduce the diarrhea rates.

Iron is considered to be one of the most important trace elements for animal growth (Brock, 1994). In order to prevent and treat iron deficiency, inorganic iron is usually added exogenously in feed production. Animals also have very different absorption rates for iron from different sources. The addition of high concentrations of iron in feed production and its low utilization rate have caused concerns about environmental pollution (Rincker et al, 2005). In the past decade, many studies have reported that metal chelates of amino acids or proteins have good utilization in animals (Creech et al, 2004; Kegley et al, 2002; Veum et al, 1995). There are also studies showing that methionine iron is more utilized than ferrous sulfate in nursery pigs (Spears et al, 1999). Yu et al, (2000) found that complex amino acid chelated iron can increase the iron content in plasma, the binding capacity of total iron in blood, and the hemosiderin and ferritin in liver and spleen of weaned piglets. However, Lewis et al, (1999, 1995) reported that the utilization of methionine iron was not as good as that of ferrous sulfate, but the utilization of protein iron and ferrous sulfate was similar.

Iron supplementation is critical for weaned piglets because they need to meet the iron requirements for increased hematocrit and rapid growth of the body. However, there are few data on the utilization of organic iron with different ligands. Therefore, the purpose of this paper is to compare the effects of several organic irons with different ligands on the growth performance of weaned piglets.

1. Experimental materials and methods

1.1 Experimental materials

Glycine iron 1, glycine iron 2, lysine iron, methionine iron, and fumarate iron were provided by Zwell Feed Co., Ltd., Nanning, Guangxi; the ferrous sulfate used in the control group was provided by Sichuan Shuxing Company.

1.2 Experimental design and animal grouping

This experiment was designed in two stages. Phase I: depletion of body iron stores. The experiment selected 54 castrated boars (about 7 kg) weaned at 24 days of age, of which 48 were fed a semi-pure diet without iron (purpose: to make all piglets have the same body iron stores, and adding iron to the diet after the body iron is depleted can produce a better effect), and 6 were fed a depleted diet + 100ppm ferrous sulfate, and were raised in a single pen as a control group. If the hemoglobin concentration of the depleted group is below 100g/l and lower than that of the control group, it means that the depletion is successful and enters the second phase of the experiment.

The 48 weaned piglets that were successfully depleted were randomly divided into 6 treatments, each with 8 replicates and 1 pig in each replicate (Table 1), and then entered the experimental period, feeding iron-supplemented diets from different sources for 28 days.

 

 

1.3 Experimental time and location

The experiment was conducted at the Animal Experiment Base of the Animal Nutrition Research Institute of Sichuan Agricultural University from November 2011 to January 2012.

1.4 Diet composition

The nutritional level of the iron-depleted diet in the first phase of the experiment was based on the nutritional requirements of 5-10kg piglets in NRC (1998). It was a semi-pure diet prepared based on corn, soybean protein concentrate, glucose, sucrose, etc., and the mineral elements were prepared and added according to NRC requirements except iron. The control group diet was prepared by adding 100ppm ferrous sulfate to the depleted diet in the first phase. The nutritional level of the basic diet formula in the second phase of the experiment was prepared based on the nutritional requirements of 10-20kg in NRC (1998), and the raw materials were basically consistent with the raw materials of the formula in the first phase of the experiment. The diet formulas for the two phases of the experiment are shown in Table 2.

 

 

1.5 Feeding and management

The immunization program and other management of the experimental pigs were carried out in accordance with the conventional pig farm management.

2 Results and analysis

2.1 Effects of different organic iron sources added to the diet on the production performance of weaned piglets

As shown in Table 2.1, the average daily weight gain effect is: glycine iron 1>glycine iron 2>ferrous fumarate>ferrous sulfate>lysine iron>methionine iron; the feed-to-weight ratio effect is: ferrous fumarate>glycine iron 1>glycine iron 2>ferrous sulfate>lysine iron>methionine iron. In this study, compared with ferrous sulfate, glycine iron 1 and glycine iron 2 can increase the daily weight gain of piglets by 10.17% and 6.27% respectively (which is consistent with the research results of Yu et al, (2000) and Feng et al, (2007) and other studies). Among the organic irons with different ligands, they have the best effect; but lysine iron and methionine iron are not as effective as ferrous sulfate in promoting piglet growth. The reason needs further study.

 

2.2 Effects of different organic iron sources added to diet on diarrhea rate and diarrhea index in piglets

 

As can be seen from Table 2.2, compared with ferrous sulfate, the effects of different organic irons on diarrhea rate and diarrhea index were not significantly different (p>0.05), but glycine iron 1, lysine iron, and methionine iron showed a decreasing trend, which may be due to the stable chemical properties of organic iron, less sulfate and crystal water, which can reduce the loss of nutrients (Allen, 2002); the methionine iron group had the lowest diarrhea rate, which may be due to the small amount of methionine contained in its corresponding diet, which can promote the intestinal development of piglets and the distribution of beneficial bacteria in the intestine (Zhang Jinxiu et al., 2009; Shoveller et al, 2005), thereby reducing the diarrhea rate of piglets in this group.

2.3 Effects of different organic iron sources added to the diet on the hair index of piglets

 

In the data of table a, n=8 for each treatment, and different lowercase letters in the same column indicate significant differences (p<0.05). The fur index of all piglets in the first week of the second phase of the experiment was 5.77±0.67, and there was no difference between the groups (p>0.05).

As can be seen from Table 2.3, the fur index of glycine iron 1 improved best with the addition time (p<0.05), which may be because glycine is one of the raw materials for synthesizing heme or the absorption and utilization rate of glycine ferrous iron is higher.

5 Conclusion

Compared with ferrous sulfate, the addition of organic iron with different ligands to the diet of weaned piglets tends to reduce the diarrhea rate; glycine iron and fumarate iron can increase the average daily weight gain of piglets, reduce feed-to-weight ratio and improve the appearance of fur, but glycine iron has a better effect; lysine iron and methionine iron have the opposite effect.

 

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