Trace elements – Selecting the right form as the key to success?

Nowadays, it is well accepted in nutrition & animal sciences that trace minerals (zinc, copper and manganese, iron, iodine, selenium) are crucial for the maintenance of health, antioxidant protection, improvement of performance and reproduction in livestock and companion animals. Generally speaking, these are the five main functions of trace minerals in order to ensure normal functions of the animals’ bodies:

• Avoiding specific deficiencies
• Achieving normal blood constituent values
• Ensuring physiological enzyme activities
• Elevating the mineral level in ‘target tissues’ as storage
• Further under debate: elevating trace element contents in food to generate so-called ‘functional foods’ (e.g. with Selenium or Iodine)

Well-known examples include, for example, the need for iron for hemoglobin in young mammals, the use of selenium for its antioxidative capacity in all life stages or the usage of zinc to maintain skin health by supporting epithelia regeneration. For these functions to be optimal, it is important to consider trace element sources of high bioavailability.

Bioavailability of trace elements in general – what does it mean?

Trace elements are essential components in the nutrition of every higher organism, although they only make up a very small proportion in the total daily ration. For this very reason, feed manufacturer and farmer themselves are constantly confronted with the importance of the different trace element compounds and their bioavailability.

In pharmacology, the term bioavailability is used to describe how quickly and comprehensively a drug substance that is administered perorally – by mouth – is absorbed through the digestive tract and is then available to the organism. The more of the active ingredient is absorbed by the body and the less of it is excreted, the higher its bioavailability.

Hereby it should be noted that before bioavailability studies could be carried out, animals were artificially brought into a severe deficiency of the investigated trace element in order to obtain maximum bioavailability values or its respective basic needs. For this reason, these values are of limited value in practice.

Difference between “organic” and “inorganic” bound – which is better?

In animal nutrition, the bioavailability of organically or inorganically bound trace elements is often compared. In this context, the descriptions ‘organic’ and ‘inorganic’ refer to the binding partners of the trace elements.

Inorganic trace elements are bound to inorganic compounds, such as sulfate, oxide, chloride or carbonate. Inorganic compounds may form complexes with other feed components, which are then no longer usable for the animal.

On the other hand, if the name contains the term ‘chelate’, the compound is organic. In addition to chelates, which are compounds of trace elements with amino acids (example: glycinates, lysinates; methionine), or peptides, one can also find, for example, acetates, fumarates, and gluconates, as well as selenium in various forms of supply, e. g. as Se methionine, as a synthesized pure substance or in the form of selenium yeasts with different organic and inorganic forms included. Although organic bound trace elements are better overall, they often need further metabolic steps to become active in the organism. Nevertheless, inorganic forms are used for decades in animal nutrition, they are cheaper than organic forms and less bioavailability was often compensated with higher dosages in the feed. But in higher dosages some elements (e.g. Cu, Zn) compete for uptake via the same transport proteins in the small intestine.

The question of “better or worse” therefore cannot be answered in a general way. It is necessary to consider the individual trace element, the circumstances (e.g. stability in feed or premixes; interaction with other substances such as binding to choline chloride or vitamins), and the animal’s needs. In certain cases, it is recommended to combine individual trace elements in inorganic and organic form in the product. In this way, the positive effects of the different binding forms can be optimally utilized.

Regarding feed law:

More detailed information on the used trace element compounds can also be obtained from your feed manufacturers. The added trace element compounds must be indicated on the label of every feed marketed in the EU. Via this way, you can always find out what kind of compound you are dealing with. Since both organic and inorganic trace element compounds occur in nature, our animals can use both forms.

Not only within the EU, but also in non-EU countries, maximum limits for e.g. zinc and copper content as well as concentrations of selenium in feed are nowadays increasingly being applied in order to minimize the effect of high dosages in regards of preventing higher concentrations of these given elements in the soil, the following interaction with the microorganisms living in it or prevent a huge enrichment in the animal-derived food-products for human consumption. So, it seems this challenge – to reduce the amount of minerals in the feed, but nevertheless to maintain health and productivity in farm animals – brings also new chances to the feed manufacturers and livestock industry to overthink old concepts of supplying minerals to farm animals.

A supply of feed containing organically bound trace elements is especially recommended for animals with high performance requirements and in stress situations (around birth process/hatching, lactation, weaning, fast growth, heat stress, vaccination, change in diet, and so on).

Organically bound trace elements have a higher bioavailability and are therefore absorbed faster and in larger quantities by the organism of the animals. This means also less shedding via feces and less impact on the environment. As an overview, we have tried to create a short summary of relevant studies in different livestock species for you regarding the most relevant trace minerals and their main biological function in the body:

Trace Elements	Target species	Main benefit / Main biological function of the trace element
Copper	Monogastric animals	Functional part of many enzymatic reactions Supports bone, connective tissue & collagen formation, functioning immune system Enhances iron absorption (gut) – Prevention of anemia Modulates microbiota Enhances growth performance Improved FCR Organic Cu: Stronger antibacterial effect than Cu sulphate
Zinc	Monogastric animals Lactating animals   Dairy cows   Broiler breeder	Modulates gut microbiota Improving intestinal health & reducing digestive disorders Enhances weight gain & general performance (especially important for young animal nutrition) Replacing antibiotics as in-feed growth promoter / can reduce need for antibiotic administration Reduced shedding of organic Zn via feces compared to ZnO Important role in immune response/ disease resistance/skin and general health Essential for keratinization/ keratin synthesis Healing & hardening of epithelial tissue Reducing chance for mastitis Less somatic cell counts in milk (especially organic forms, e.g. Zn-chelates) Egg shell improvement leading to extra chicks hatched over lifetime Zn amino chelates superior over Zn sulphate
Manganese	All Animals	Essential for proper enzyme production (involved in energy production, bone development, reproduction) Mn-chelates superior to inorganic Mn in improving FCR Enhanced carcass quality with less fat deposition
Iron	Monogastric animals	Prevention of anemia in newborn animals Essential for healthy blood (main part of hemoglobin) + oxygen storage in muscle tissue (part of myoglobin) Can increase concentration in meat and milk
Selenium	Mammals and birds    Dairy cows	Antioxidant protection Positive effects on fertility Transfer of organic Se via placenta/milk and yolk sac & enrichment of food with Se (egg, milk) for human consumption Prevention of mastitis
Iodine	All animals Mammals and birds	Maintaining thyroid hormone metabolism and proper function of thyroid hormones for normal performance Prevention of endemic goiter Iodine-enrichment of food for human consumption (egg, milk)

So, this was a list of effects of single trace elements and their biological function. Nevertheless, combined effects could not be addressed in this table, so we will mention a few examples of useful mixtures here as follows:

• The involvement of Zn, Mn and Cu in the formation of bone matrix and eggshell formation. As many studies suggest, fulfilling the needs for trace minerals, specifically sourcing from organic bound forms, can tremendously help on supporting joint and hoof health.
• Supplementation of Zn and Mn chelates to broiler breeders lead to reduction of early mortality in chicks
• An observed reduction in mortality & leg abnormalities in turkeys via supplementation of methionine chelates of Zn and Mn
• Improved fertility rates in mammals when combining above mentioned trace elements
• Organic sources of Zn, Mn and Cu showed advantages in terms of immunoglobulin production in the blood of dairy cows compared to the supplementation with their sulfate counterparts (Roshanzamir et al., 2020).
• And this list could be continued endlessly.

Solutions from XVET

XVET has a vast range of products containing a favorable mixture of inorganic and organic trace elements supporting all different kind of animal species, in all different stages of their life cycle and who are facing a broad spectrum of challenges. If you have questions regarding these products, such as Ferti R, Zincotin, Sel X, Vitaquamix, Pro Sow Oestrus and Fertitab-S , please, do not hesitate to contact the XVET team for further support under info@xvetgermany.com.