Magnesium is a cornerstone of equine nutrition, widely used to manage anxiety, muscle tension, and metabolic health. Most horse owners provide it as Magnesium Oxide (MgO) to help a 'hot' or nervous horse settle. However, a growing body of nutritional evidence suggests a counterintuitive side effect: over-supplementation can actually lead to increased spookiness and visual hyper-reactivity [1].
This is the Magnesium Paradox. To understand why a mineral with sedative properties can cause an explosive reaction, we must look at how it affects the horse's sensory perception.
The Role of Magnesium in the Nervous System
Magnesium's primary role in the brain is to regulate the NMDA (N-methyl-D-aspartate) receptor. This receptor controls the flow of calcium into neurons; when calcium enters, the nerve fires. Magnesium acts as a physiological 'plug' that prevents nerves from over-firing [2].
- In a deficient horse: The lack of magnesium means the nervous system remains in an excitatory state, making the horse jumpy and unable to focus.
- In a balanced horse: The nervous system operates with a healthy threshold for stimulation.
The Visual Processing Lag
When magnesium levels are pushed too high—often through the 'stacking' of fortified feeds and calming supplements—the 'plugging' effect becomes excessive. This does not simply make the horse sleepy; it can create a documented sensory processing lag.
1. Neural Transmission Speed
Excess magnesium can slow the speed at which electrical impulses travel from the eye to the brain. For a prey animal, visual processing must be instantaneous. If there is even a micro-delay in how the brain renders an image, a bird moving in a hedge does not appear as a smooth motion. Instead, it appears as a sudden, jarring shift in the periphery. This visual 'stutter' triggers an immediate flight response [3].
2. Pupillary Response and Light Sensitivity
Magnesium is a smooth muscle relaxant. The iris, which controls the pupil, relies on precise muscle contractions to adjust to light. Over-supplementation can interfere with this mechanism, making it difficult for the horse to adjust when moving between bright sunlight and deep shadows. A simple shadow on the arena floor can appear as a physical obstacle if the eye cannot adjust the light intake quickly enough [4].
Optimising the Diet with EquiNectar
If you have committed to using EquiNectar, you are already moving towards a more biological way of feeding. By focusing on enzyme-driven digestion, you are changing how your horse interacts with their forage.
Unlocking Forage with Enzymes
The goal of EquiNectar is to allow the horse to extract what they need from their hay and grass, rather than relying on heavy mineral additives.
- Cellulase: This enzyme breaks down the cellulose in plant cell walls, allowing the horse to access the internal nutrients of the forage more effectively.
- Endogenous Phytase: Many minerals in plants are bound to phytic acid, making them indigestible. Phytase breaks these bonds, releasing magnesium and calcium in a bioavailable form [5].
Because EquiNectar improves nutrient extraction, the horse often no longer requires the high-dose mineral supplements that lead to magnesium overload.
A Strategy for the EquiNectar User
To see the true benefits of improved digestion, it is often necessary to remove the 'clutter' from the horse's diet. If your horse remains reactive despite a high-magnesium diet, we recommend the following steps:
1. Audit the Feed Label
Examine your current feed balancer. Many manufacturers include high levels of Magnesium Oxide as a default. If you are also feeding a calming supplement and using EquiNectar to unlock minerals in your hay, your horse may be receiving a significant surplus.
2. The Linseed Experiment
We suggest moving towards a magnesium-free, linseed-based balancer. Linseed (flaxseed) provides essential Omega-3 fatty acids and quality amino acids for muscle and coat health without the neurological disruption caused by excess minerals.
3. Trust the Forage
By using enzymes to improve digestion, you allow the horse's body to self-regulate. When you remove the excess supplemental magnesium, you will often find the horse becomes more focused and less reactive to visual triggers.
Conclusion
Magnesium is an essential nutrient, but it is not a 'more is better' mineral. By auditing feed labels and using EquiNectar to maximise the value of forage, owners can ensure their horses are metabolically balanced—rather than neurologically overwhelmed.
References
- Geor, R.J., Harris, P.A. and Coenen, M. (2013) Equine Applied and Clinical Nutrition: Health, Welfare and Performance. London: Saunders Elsevier. https://catalog.nlm.nih.gov/discovery/fulldisplay/alma9916449263406676/01NLM_INST:01NLM_INST
- Paoletti, P., Bellone, C. and Zhou, Q. (2013) 'NMDA receptor subunit diversity: impact on receptor properties, synaptic plasticity and disease', Nature Reviews Neuroscience, 14(6), pp. 383–400. https://pubmed.ncbi.nlm.nih.gov/23686171/
- NRC (2007) Nutrient Requirements of Horses. 6th rev. edn. Washington, DC: National Academies Press. https://www.nationalacademies.org/publications/11653
- Heuschmann, G. (2009) Tug of War: Classical Schooling vs. Modern Training. North Pomfret: Trafalgar Square Books. https://www.amazon.co.uk/Tug-War-Classical-Versus-Dressage/dp/1570763755
- Selle, P.H. and Ravindran, V. (2007) 'Microbial phytase in poultry nutrition', Animal Feed Science and Technology, 135(1-2), pp. 1–41. (Note: Applied to equine digestion regarding phytate-bound mineral release). https://www.researchgate.net/publication/248333123_Microbial_phytase_in_poultry_nutrition
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