Chelates in animal nutrition

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Zinc sample

Chelates in animal feed are organic forms of essential trace minerals such as copper, iron, manganese and zinc.

Animals absorb, digest and use mineral chelates better than inorganic minerals.[1] This means that lower concentrations can be used in animal feeds. In addition, animals fed chelated sources of essential trace minerals excrete lower amounts in their faeces, and so there is less environmental contamination. Mineral chelates also offer health and welfare benefits in animal nutrition.

Brief history of chelates[edit]

Since the 1950s, animal feeds have been supplemented with essential trace minerals such as copper (Cu), iron (Fe), iodine (I), manganese (Mn), molybdenum (Mo), selenium (Se) and zinc (Zn). Initially, such supplementation was by means of inorganic salts of essential trace elements. Chelated minerals were first developed in the early 1970s, but saw more growth in the1980s and 1990s. Trace mineral chelates have proven to be better than inorganic minerals in meeting the nutritional needs of modern farm animals.[2]

Role and source of minerals[edit]

The objective of supplementation with trace minerals is to avoid a variety of deficiency diseases. Trace minerals carry out key functions in relation to many metabolic processes, most notably as catalysts for enzymes and hormones, and are essential for optimum health, growth and productivity. For example, supplementary minerals help ensure good growth, bone development, feathering in birds, hoof, skin and hair quality in mammals, enzyme structure and functions, and appetite. Deficiency of trace minerals affect many metabolic processes and so may be manifested by different symptoms, such as poor growth and appetite, reproductive failures, impaired immune responses, and general ill-thrift. From the 1950s to the 1990s most trace mineral supplementation of animal diets was in the form of inorganic minerals, and these largely eradicated associated deficiency diseases in farm animals.

The role in fertility and reproductive diseases of dairy cattle highlights that organic forms of Zn are retained better than inorganic sources and so may provide greater benefit in disease prevention, notably mastitis and lameness.

Poultry and nutrition

Sources of essential minerals[edit]

In recent decades, global food animal production has intensified and genetic potential for growth and yields has improved. As a result, commercial tendencies have been to increase trace mineral supplementation in order to allow for the greater mineral requirements of superior stock reared under industrial conditions. Increasing the concentration of inorganic minerals in animal diets has led to several problems.

The use of high Cu in swine and poultry rations has caused accidental Cu poisoning in more sensitive animals, such as sheep grazing pastures fertilised with pig or poultry manure. Secondly, inorganic minerals may form insoluble complexes with other dietary agents, resulting in low absorption. In addition, it is thought that the positive charge of many inorganic minerals reduces access to the enterocytes due to repulsion by the negatively charged mucin layer and competition for binding sites.

Finally, the poor retention and high excretion rates of inorganic minerals led to environmental concerns during the 1980s and 1990s, especially in Europe. The European Union is concerned about possible detrimental effects of excess supplementation with trace minerals on the environment or human and animal health, and in 2003 legislated a reduction in permitted feed concentrations of several trace metals (Co, Cu, Fe, Mn and Zn).[3]

Research in trace element nutrition has led to the development of more bioavailable organic minerals, including trace minerals derived from chelates. Chelates allow a lower supplementation rate of trace minerals with an equivalent or improved effect on animal health, growth and productivity.

Particular types of chelates[edit]

  • Chelates are organic molecules, normally consisting of 2 organic parts with an essential trace mineral occupying a central position and held in place by covalent bonding.
  • Proteinate is a particular type of chelate, in which the mineral is chelated with short-chain peptides and amino acids derived from hydrolysed soy proteins and contain roughly 10-20% of the trace mineral.[4] In proteinates, minerals are bound to various amino acids with different levels of stability.
  • Amino-acid complex, such as glycinates or methionates, are other particular types of chelate, in which the mineral is chelated with an amino acid. Based on one single type of amino-acid, the product is pure (there is only one type of bond or chelation between minerals and the ligand) and it is therefore easier to work on stability and ensure a full chelation. Moreover, depending on the size of amino acid, it is also possible to increase the metal content.


Zinc sample
Copper sample
  • The utilisation of organic Cu from a copper chelate or copper lysine is higher than that of inorganic Cu sulfate when fed to rats in the presence and absence of elemental Zn or Fe. The data suggest that, unlike inorganic Cu, organic Cu chelates exhibit absorption and excretion mechanisms that do not interfere with Fe. Copper chelate also achieved higher liver Zn, suggesting less interference at gut absorption sites in comparison with the other forms of Cu.[5][6]
  • The effects of organic zinc sources on performance, zinc status, carcass, meat, and claw quality in fattening bulls has been studied. Livestock Prod.[7] compared a Zn chelate, a Zn polysaccharide complex and ZnO (inorganic zinc oxide) in bull beef cattle, and concluded that the organic forms resulted in some improvement in hoof claw quality.
  • The bioavailability of Cu and Zn chelates in sheep have been compared to the inorganic sulfate forms, at "low" and "high" supplementation rates. Copper and Zn chelates at the lower rates caused significantly greater increases in blood plasma concentrations than the corresponding treatments with Zn sulfate (p<0.05) and Cu sulfate (p<0.01). In addition, zinc chelate supplementation resulted in significantly greater hoof and horn Zn content than did Zn sulfate (p<0.05). At the "low" supplementation rate, zinc chelate achieved better hoof quality than Zn sulfate (p<0.05). The data suggest that Cu and Zn chelates are more readily absorbed and more easily deposited in key tissues such as hooves, in comparison with inorganic Zn forms.[8]
  • In weaned piglets, various supplementation rates of organic Zn in the form of a chelate or as a polysaccharide complex have been evaluated and compared with ZnO, zinc oxide, at 2,000 ppm. Feeding lower concentrations of organic Zn greatly decreased the amount of Zn excreted in comparison with inorganic Zn, without loss of growth performance.[9]
  • Copper chelate in weaned pigs have been compared with inorganic Cu and sulfate. Piglet performance was consistently better with organic Cu at 50 to 100 ppm, in comparison with inorganic Cu at 250 ppm. In addition, organic Cu increased Cu absorption and retention, and decreased Cu excretion 77% and 61% respectively, compared with 250 ppm inorganic Cu.[10]
    Magnesium sample
  • The effects of an Mg chelate in broiler chickens have been compared with magnesium oxide and an unsupplemented control group. Diets for fattening chicken are not normally supplemented with Mg, but this study indicated positive effects on performance and meat quality. During the first 3 weeks of life, the Mg chelate improved feed efficiency significantly in comparison with both the inorganic MgO and the negative control group (p<0.05). Thigh meat pH and oxidative deterioration during storage were also studied. The Mg chelate increased thigh meat pH in comparison with the negative control (p<0.05). Mg supplementation significantly reduced chemical indicators (TBARS) of oxidative deterioration in liver and thigh muscle (p<0.01), with Mg chelate significantly more efficient than MgO (p<0.01). The data suggest that organic Mg in the form of a chelate is capable of reducing oxidation, and so improve chicken meat quality.[11]
  • A Zn chelate supplement was compared with Zn sulfate in broiler chickens. Weight gain and feed intake increased quadratically (p<0.05) with increasing Zn concentrations from the chelate and linearly with Zn sulfate. The relative bioavailability of the Zn chelate was 183% and 157% of Zn sulfate for weight gain and tibia Zn, respectively. The authors concluded that the supplemental concentration of Zn required in corn-soy diets for broilers from 1–21 days of age would be 9.8 mg/kg diet as Zn chelate and 20.1 mg/kg diet as Zn sulfate, respectively.[12]
  • The effects of replacing inorganic minerals with organic minerals in broiler chickens have been studied. One group of chickens received inorganic sulfates of Cu (12 ppm), Fe (45 ppm), Mn (70 ppm) and Zn (37 ppm) and their performance was compared to a similar group supplemented with chelates of Cu (2.5 ppm), Fe, Mn, and Zn (all at 10 ppm). There were no differences in performance between the birds fed the high inorganic minerals and the birds fed the low organic chelates. Faecal concentrations of Cu, Fe, Mn and Zn were 55%, 73%, 46% and 63%, respectively, of control birds fed inorganic minerals.[13]
  • A study compared inorganic and organic mineral supplementation in broiler chickens. Control birds were fed Cu, Fe, Mn, Se and Zn in inorganic forms (15 ppm Cu from sulfate; 60 ppm Fe from sulfate etc.), and compared with three treatment groups supplemented with organic forms. Apart from improved feathering, most likely associated with the presence of organic Se, there were no significant performance differences between birds fed inorganic and organic minerals. The authors concluded that the use of organic trace minerals permits a reduction of at least 33% in supplement rates in comparison with inorganic minerals, without compromising performance.[14]


  1. ^ Richards, James D.; Fisher, Paula M.; Evans, Joseph L.; Wedekind, Karen J. (2015-06-25). "Greater bioavailability of chelated compared with inorganic zinc in broiler chicks in the presence or absence of elevated calcium and phosphorus". Open Access Animal Physiology. Retrieved 2019-12-20.
  2. ^ (McCartney, 2008)
  3. ^ Commission Regulation (EC) No 1334/2003 of 25 July 2003 amending the conditions for authorisation of a number of additives in feedingstuffs belonging to the group of trace elements. 26.7.2003 EN Official Journal of the E.U.
  4. ^ "Chelated Ingredients". Watson Inc. Retrieved 2019-12-20.
  5. ^ quote by Du et al.,1996
  6. ^ Z. Du, R.W. Hemken, J.A. Jackson and D.S. Trammell (1996) Utilization of copper in copper proteinate, copper lysine and cupric sulfate using the rat as an experimental model.Journal of animal science
  7. ^ Sci. 81:161-171.
  8. ^ J. P. Ryan, P. Kearns and T. Quinn (2002) Bioavailability of dietary copper and zinc in adult Texel sheep: A comparative study of the effects of sulfate and Bioplex supplementation. Irish Veterinary Journal
  9. ^ M.S. Carlson, C.A. Boren, C.Wu, C.E. Huntington, D.W. Bollinger and T.L. Veum (2004) Evaluation of various inclusion rates of organic zinc either as polysaccharide or proteinate complex on the growth performance, plasma and excretion of nursery pigs. J. Anim. Science
  10. ^ T.L. Veum, M.S. Carlson, C.W. Wu, D.W. Bollinger and M.R. Ellersieck (2004) Copper proteinate in weanling pig diets for enhancing growth performance and reducing fecal copper excretion compared with copper sulfate. J. Anim. Sci
  11. ^ Y. Guo,Zhang,Yuan and W. al.,2003,Effects of source and level of magnesium and Vitamin E on prevention of hepatic peroxidation and oxidative deterioration of broiler meat., Sci.Tech.
  12. ^ T. Ao, J.L. Pierce, R. Power, K.A. Dawson, A.J. Pescatore, A.H. Cantor and M.J. Ford (2006) Investigation of relative bioavailability value and requirement of organic zinc for chicks. J. Poultry. Sci
  13. ^ quote by Nollet et al.2007
  14. ^ by Peric et al.2007
Topics of the works
  • SCAN (2003a) Opinion of the Scientific Committee for Animal Nutrition on the use of copper in feedingstuffs.
  • SCAN (2003b),Opinion of the Scientific Committee for Animal Nutrition on the use of zinc in feedingstuffs.
  • Commission Regulation (EC) No 1334/2003 of 25 July 2003 amending the conditions for authorisation of a number of additives in feedingstuffs belonging to the group of trace elements. 26.7.2003 EN Official Journal of the European Union .
  • E. McCartney (2008) Trace minerals in poultry nutrition–sourcing safe minerals, organically? World Poultry
  • D. Wilde (2006). Influence of macro and micro minerals in the peri-parturient period on fertility in dairy cattle. Animal Reproduction.