Iron is a trace element essential for pig growth. The main physiological role of iron in pigs is to participate in the process of oxygen transport, transformation and tissue respiration, and at the same time affect the synthesis and immune function of proteins in animals, which is closely related to energy metabolism. The amino acid chelated iron is composed of an amino acid and an iron element. It is an iron additive similar to the absorption form and biological function form of the animal, and has no toxic side effects and deposition phenomenon in the animal body. Numerous studies have shown that amino acid chelated iron has functions such as improving piglet growth performance, improving fur, improving immunity, preventing iron deficiency anemia, reducing the amount of trace elements in the diet, and reducing the pollution of trace elements to the environment. An ideal feed additive. Studying the application of amino acid chelated iron in weaned pig production can find a feasible iron supplement method for the sustainable development of modern pig industry, which has important practical significance.
Description of 1 amino acid iron
The American Association of Feed Management Officials (MFCO, 1996) specifically describes amino acid chelated iron: amino acid chelated iron refers to an iron ion in a soluble iron salt that is covalently bonded to a certain amino acid at a certain molar ratio. Thus, 1 mol of iron is combined with 1 to 3 mol (preferably 2 mol) of amino acid, and the average molecular weight of the hydrolyzed amino acid is required to be about 150, and the molecular weight of the resulting chelate is not more than 800.
Nutritional characteristics of 2 amino acid chelated iron
2.1 stable chemical properties
Bieh (1997) reported that dietary protein deficiency and cellulose, phytic acid, mineral elements and some anti-nutritional factors (gossypol, tannin, etc.) can inhibit the absorption of inorganic iron, among which cellulose and phytic acid are easy. Insoluble complex with inorganic iron, calcium, phosphorus and copper in the feed are too high to antagonize inorganic iron, and anti-nutritional factors combine with ferrous iron to hinder the absorption of inorganic iron. In the amino acid chelated iron, the combination of Fe and amino acid forms a relatively stable chemical structure, which protects the biological titer of iron ions from the adverse effects of other components in the diet and gastric acid in the gastrointestinal tract. It has stable chemical properties, strong solubility, dynamic distribution in the small intestine, small influence by other substances, easy to be absorbed into the blood by the small intestinal mucosa, and is needed for the whole body cells.
2.2 high biological potency
The amino acid chelated iron molecule is electrically neutral. It is not only the main form of the body's absorption of iron ions, but also an intermediate substance in the biochemical process of animals. It does not form resistance and sedimentation in the intestine. Moreover, the protein or amino acid acts as an unsaturated substance of the ligand, and the stability constant is generally between 4 and 15, which is advantageous for the combination with the trace element to form a chelate to be transported, and if necessary, can effectively be used from the chelate (carrier) It is released so that the protein or amino acid chelate may be absorbed directly through the intestinal wall. According to Graff (1970), the absorption rate of amino acid chelated iron is 4.9 times that of inorganic iron (ferrous sulfate, iron carbonate, iron oxide). Ettle et al. (2008) found that theglycine iron was more bioavailable than the ferrous sulfate in the study of weaned piglets.
2.3 Nutrition and disease resistance, anti-stress effect
Amino acid chelated iron has a dual nutritional effect. It has the functions of enhancing antibacterial ability, improving immune response, and promoting animal cell and humoral immunity. It has a therapeutic effect on certain enteritis, dermatitis, dysentery and anemia, and at the same time enhances the activity of enzymes in the body, thereby improving production performance. Yuan Shulin reported that the good anti-stress function of amino acid chelated iron can alleviate the stress caused by weaning, castration, high temperature and changing diet. Chirase and other tests have shown that the chelated form of trace elements has the effect of enhancing bactericidal ability and improving immune response.
2.4 Improve the utilization of nutrients
Yuan Shulin et al. (2003) demonstrated that amino acid chelated iron can enhance the activity of enzymes in the body and improve the utilization of protein, fat and vitamins. Cocato et al. (2008) studied 44 weaned piglets at 21 days of age and found that adding methionine iron to feed increased the feed conversion rate more than adding ferrous sulfate. Lu Yufa et al. (2002) also proved that amino acid chelated iron has the effect of significantly improving feed utilization.
Reduce environmental pollution; amino acid chelated iron has good palatability and reduces waste; amino acid chelated iron provides iron for the body and can also supplement essential amino acids.
Application Status of 3 Amino Acid Chelated Iron in Weaned Piglets
3.1 Influence on production performance, skin color and hair condition
3.1.1 Impact on production performance 1 Domestic and foreign studies have shown that the application of amino acid chelated iron in weaned piglets can significantly increase its daily gain.
Kuznetsov et al. (1987) reported that the addition of methionine iron to the weaned large white pig diet at 26 days of age increased the daily weight gain of pigs by 16.6% compared with the addition of ferrous sulfate. This is in contrast to the results of Cromwe 11 (1986) and Han Youwen (2001). Consistent. Xu Jianxiong (1994) added 30 mg/kg, 60 mg/kg, and 90 mg/kg of methionine iron to the piglet diet, which was significantly higher than the control group by 8.05%, 9.99%, and 6.59%, respectively. It is 60 mg/kg.
2 Because the amino acid chelated iron has stable chemical properties and is easy to be absorbed by animals, its application in weaned piglets has the effect of improving feed utilization and reducing the ratio of meat to meat. A large number of experiments have shown that amino acid chelated iron has a significant effect on reducing the rate of diarrhea in weaned piglets.
Lu Yufa et al. (2002) tested 28 days of 28-day-old weaned piglets with a 30-day amino acid chelated iron additive and an inorganic salt additive diet. The results showed that the average daily gain was increased by 8.3% and the feed efficiency was increased by 8.1%. Guo Haitao (2005) showed that 100mg/kg complex amino acid chelated iron can significantly increase daily gain, lower feed-to-meat ratio and diarrhea rate (P<0.05). Wang Mingzhen (2007) showed that the improvement of growthperformance of weaned piglets was best when the level of amino acid chelated iron in the diet was 120 mg/kg on the basis of 100 mg/kg inorganic iron. It can significantly increase the daily weight gain of piglets, and can significantly reduce the feed-to-weight ratio (P<0.01) and significantly reduce the diarrhea rate of weaned piglets (P<0.05).
Liu Weidong et al. (2008) showed that after adding 0.05% glycine chelated iron to the basal diet of 28-day-old weaned pigs, the average daily weight gain of the test group with glycine-chelating iron was lower than that of the control group fed only with the basal diet. Increased by 9.1%, the ratio of meat to meat decreased by 6.2%, and the rate of diarrhea decreased by 56.3%. Ye Ting (2011) test proved that the addition of threonine iron in the diet can effectively promote the growth of weaned piglets, improve their production performance (P<0.05), and significantly reduce the ratio of meat to meat (P<O.Ol).
3.1.2 Effects on skin color and gross condition The fur index is an important indicator for pig production. In the case of ensuring the performance of pigs, people often choose pigs with bright red hair during the process of buying and selling pigs.
Guo Haitao (2005) showed that the composite amino acid chelated iron compared with inorganic iron significantly increased the pig fur score (P<0.01). Within 30 to 120 mg/kg, the sensory effect was more pronounced with increasing dose. Wang Mingzhen (2007) test results show that the addition of 120mg/kg amino acid chelated iron is a suitable dose for improving piglet skin.
3.2 Effects on Iron Storage and Apparent Absorption Rate of Trace Elements in Tissues and Organs of Piglets
Yu et al (2000) reported that the addition of complex amino acid chelated iron significantly increased liver and spleen hemosiderin and transferrin content compared with the addition of the same dose of FeSO4. Wang Mingzhen (2007) showed that adding 120mg/kg amino acid chelated iron to the diet significantly improved the apparent digestibility of iron in piglets and the iron storage level in piglets compared with the control group (P). <0.01). Fang et al (2009) added glycine chelated ironand ferrous sulfate to 24 weaned pig diets, and found that at the level of 120 mg/kg, the addition of glycine iron group compared with the addition of ferrous sulfate group, glycine chelated iron group The expression of small peptide transporter 1 (PEPT1) mRNA in duodenum and jejunum of piglets was significantly increased (P<0.05), and the expression level of membrane transporter (Ferroportin 1) mRNA was significantly decreased (P<0.05).
3.3 Effects on blood physiological and biochemical indexes of piglets
Serum iron content is highly correlated with iron storage in the body and is a direct response to pig iron status. Serum urea nitrogen can reflect the situation between protein metabolism and amino acid balance in animals. Relevant research at home and abroad has demonstrated the ability of amino acid chelated iron to improve the iron nutrition status of piglets through serum iron, hemoglobin levels, serum transferrin and other related indicators. At the same time, through the serum urea nitrogen and IgG and other related indicators, the amino acid chelated iron has a positive effect on improving blood biochemical indicators in piglets.
Yu et al (2000) reported that the addition of complex amino acid chelated iron significantly increased hematocrit, hemoglobin levels and plasma iron levels compared with the addition of the same dose of FeS04. Wang Mingzhen (2007) showed that the addition of amino acid chelated iron 120mg/kg and 160mg/ Kg can significantly increase serum iron (P<0.05), and the addition of amino acid chelated iron 120mg/kg can significantly increase serum transferrin (sTf) content and hemoglobin index, decrease TIBC and serum urea nitrogen level (P<0.05). The addition of amino acid chelated iron 160mg/kg significantly increased the serum transferrin (sTf) content (P<0.01), and significantly decreased serum urea nitrogen levels (P<0.05).
However, Jin Hong et al (2002) concluded that iron methioninate had no significant effect on hemoglobin and hematocrit in pigs. Guo Haitao (2005) believes that adding high doses of chelated iron on the basis of inorganic iron does not significantly increase serum iron. An important reason for these gaps is that the iron content of the diet, the iron content of the weaned piglets and the pH of the intestines can affect the iron absorption of weaned piglets. The specific mechanism is unknown.
Chen Fengqin (2008) showed that the serum IgG content of the ferrous ferrous group was significantly higher than that of the inorganic ferrous sulfate group and the ferrous fumarate group (P<0.01). Ma Wenqiang et al (2008) pointed out that the addition of glycine iron to the diet of weaned piglets can reduce the levels of blood urea nitrogen, calcium and phosphorus in serum. Ye Ting (2011) suggested that the addition of threonine iron in the diet can increase serum iron content, serum transferrin saturation and IgG content, enhance the immune function of piglets, and have a positive effect on improving blood biochemical indicators of piglets. The effects were 100 mg/kg and 125 mg/kg, and were more obvious (P<0.01).
The application prospect of 4 amino acid chelated iron
Although a large number of experimental studies have proved that the application of amino acid chelated iron in the pig industry has a positive effect, there are still some problems to be solved in the promotion and application of amino acid chelated iron in actual production.
First of all, the production cost is high, the process is complicated, the production conditions are strict, and it is difficult to apply it in actual production. In the future, we should focus on research and improvement of product formulation and process design, select appropriate production process routes, and reduce production costs. Secondly, the qualitative and quantitative analysis of current organic trace element products is not perfect. The spectrophotometric method and potential method are usually not suitable for qualitative and quantitative analysis of products. It is difficult to accurately detect the chelation rate and stability of amino acid chelated iron. It is difficult to regulate the production, sale and application of organic trace elements. Therefore, the establishment of qualitative and quantitative detection of new technologies to improve the quality of amino acid chelated iron is the focus of future research work. Of course, continue to study the absorption and metabolism mechanism of organic iron in animals, the hematopoietic function of the body and the best chelation form suitable for animal body utilization. The optimal addition time and dosage are also of great significance for the promotion and application of amino acid chelated iron.
Amino acid chelated iron has significant nutritional effects and broad application prospects for weaned piglets. It is necessary to strengthen research and development work, select appropriate production routes, improve product quality, further understand the mechanism of amino acid chelate iron absorption, strengthen promotion and application, and promote nutrition. The sustainable development of the pig industry.