Does redox matter for animals?

In animal nutrition, nothing is arbitrary, especially when it comes to trace minerals. Copper, for instance, is required at just 10 to 20 ppm in most swine and poultry diets, a remarkably small quantity compared to other essential nutrients. This raises a simple but important question: If nature sets the copper requirement so low, is there a reason for it, and could we increase the dosage without consequences?

Over the past decades, nutritionists have demonstrated that increasing copper to pharmacological levels (150–250 ppm), particularly in growing piglets or broilers, has consistent benefits on performance. Short-term use improves average daily gain (ADG), feed conversion ratio (FCR), and gut health. However, when used over longer periods, during grower or finisher stages, this high copper inclusion can backfire. Performance gains may plateau or reverse, and the risk of toxicity increases, with evidence of liver accumulation, and tissue stress.

This paradox leads to a broader reflection: What if the redox potential of ingredient plays a role in their toxicity implications?

What is redox potential?

Redox potential (or reduction potential) is a measure of how easily a substance can gain or lose electrons during a chemical reaction. It’s expressed in volts (V) and reflects the electron-transfer activity of an element. In biological systems, this property is crucial: many enzymes require trace minerals to accept or donate electrons as part of metabolic and detoxification processes.

Each mineral has a characteristic redox potential, especially those that cycle between ionic states. Minerals with high redox potential will strongly attract electrons. Inside the cell, if unbound, these minerals can interact directly with DNA, proteins, lipids, and cell membranes, stealing electrons and denaturing their structure. This silent oxidative attack weakens the integrity of muscle cells, denatures proteins, and initiates lipid peroxidation.

The consequences, though invisible during feeding, become apparent at slaughter. The meat may retain less water, resulting in drier texture and higher drip loss. Oxidized fats contribute to off-flavors and rancidity, while damaged pigments lead to dull, brownish tones instead of the vibrant red consumers expect. In severe cases, this process can compromise the tenderness, juiciness, and shelf life of the final product, subtle losses in quality that trace back to the cellular toll of uncontrolled copper reactivity.

The table below illustrates the difference level of oxidative potential of the major minerals used in animal nutrition.

• Minerals with high redox potential (like divalent copper coming from copper sulfate and copper chloride / TBCC) are generally more reactive and required in lower amounts.

• Minerals like zinc, manganese or calcium which do not engage in redox reactions, are used in structural or catalytic roles, and thus needed in much higher quantities.

  This relationship isn't absolute, but it’s consistent enough to suggest that redox potential influences both potency and requirement, and potentially, toxicity risk.

  While redox-active minerals drive critical biochemical reactions, their reactivity must be controlled. When present in excess or in highly soluble ionic forms, they may catalyze undesirable reactions or accumulate in tissues. Copper sulfate (CuSO₄), a commonly used copper source, provides divalent Cu²⁺ ions that are rapidly absorbed, but also have a greater tendency to trigger side effects when used at high doses over long periods. TBCC (Copper Chloride) may be a less soluble source but will result as well in the release of divalent copper (Cu²⁺).

  As a result, recent research has explored whether using alternative forms of copper with lower redox potential, for example, those providing monovalent Cu⁺ instead of Cu²⁺, could reduce the risk of toxicity while maintaining performance benefits.

  Some stabilized Cu⁺ sources (specifically dicopper oxides) may exhibit:

• Slower release in the gastrointestinal tract

• Reduced accumulation in the liver

• Lower activation of stress-related biomarkers (MDA,

• These benefits do not compromise the growth-promoting effect, which may result from mechanisms beyond redox chemistry, such as interactions with microbial populations, enzyme modulation, or nutrient absorption efficiency.

  
  

  What are the implications for nutrition?

  Understanding the redox behavior of minerals opens new perspectives for designing safer and more effective supplementation strategies:

  1.     Don’t just consider the dose, consider the form. Two sources delivering the same element can behave very differently in the body, especially when redox properties are involved.

  2.     Short-term use of high-dose copper is effective, but for long-term feeding (grower and finisher phases), forms with lower redox potential and better safety profiles may be preferable.

  3.     Redox-active minerals must be balanced with the animal’s antioxidant capacity (e.g., selenium, vitamin E) to prevent oxidative stress.

  4.     Future formulations may benefit from matching the mineral’s redox behavior to its biological context, delivering redox-active forms where electron transfer is needed, and inert forms where structure or stability is the goal.

  

  
  

  The concept of redox potential provides a powerful framework to understand why certain minerals are required in such small quantities, and how their form and reactivity influence both benefit and risk. In the case of copper, nature's requirement, just 10 to 20 ppm, is no coincidence. It reflects millions of years of biological refinement, where just enough copper is used to power essential enzymes without endangering cells through oxidative stress.

  
  

  When we choose to go beyond these natural levels, whether for performance or health purposes, we must proceed with care. Nature does not set its limits arbitrarily, and deviating from them without understanding the consequences can lead to unintended outcomes, from oxidative damage to reduced animal performance and even compromised meat quality.

  
  

  The selection of minerals should not be driven by price alone or feed cost reduction, but must also consider their biological activity, particularly their redox potential, and the impact this has on animal physiology and long-term productivity.

  By deepening our understanding of how mineral redox states interact with biological systems, we can make more informed, more precise decisions. Selecting the right form, at the right dose, and for the right duration is not only safer for the animal, it also supports better feed efficiency and farm performance.

  
  

  In a time when both productivity and sustainability matter more than ever, this kind of nutritional precision isn’t just ideal; it’s essential.

  David Serène

  Nutrispices Director