Why Equine Nutrition Advice Takes Time to Change

If you have owned horses for any length of time, you will have seen feeding advice change.

What was once considered essential is later questioned. Practices that were widely recommended gradually fall out of favour. New approaches emerge, often based on better data and improved understanding of how the horse actually works.

This is not a sign that the industry is unreliable. It is a reflection of how science progresses.

However, what happens is that there is often a discrepancy between the results of research and the recommended practices. These differences persist over several years, and sometimes even several decades.

It is important to understand why this gap occurs so that horse owners can make better decisions.

Iron in horse feed

For many years, iron was routinely included in horse feed formulations. This was based on the long-standing assumption that supplementation was beneficial and necessary to support health.

However, as forage analysis became more widely available and larger datasets were examined, a different picture began to emerge. Grass and hay were consistently shown to contain high levels of iron, often far exceeding the horse’s actual requirements.

At the same time, further investigation highlighted additional contributors to iron intake, including soil contamination and the use of lower-cost mineral sources in some feeds and supplements. These factors could significantly increase total iron intake beyond what would naturally occur in forage alone.

As awareness of this increased, attention turned to the potential consequences of excess iron. Emerging evidence and clinical observations began to explore links between elevated iron intake and metabolic health, hoof quality, and liver function.

At Forageplus, we began raising these concerns early, based on forage analysis data and a growing body of scientific evidence. This included highlighting both the naturally high iron content of forage and the additional impact of certain mineral forms used in feed.

At the time, this position was not part of mainstream thinking. It was met with criticism in some areas, particularly on social media and from a small number of nutritionists and veterinary professionals. The prevailing view continued to support the routine inclusion of iron, and the concept of excess was not widely considered.

This is reflected in statements such as ‘supplementing a little does no harm if your forage is typical,’ illustrating the assumption that excess iron intake is unlikely to be problematic.

However, as larger forage datasets became available, it became clear that this assumption did not hold true in many cases, particularly in UK conditions where forage iron levels are consistently high.

This is a consistent pattern when established practices are challenged. Early interpretation of emerging data often sits outside accepted norms, and as a result, is frequently questioned or dismissed.

However, as more data became available and understanding improved, the position began to shift:

• Feed companies began removing added iron
• Products were reformulated
• Guidance was updated

Many UK feed companies have moved away from routinely adding iron to balancers and supplements. Evidence of this shift can be seen in how many modern balancer products are now formulated and marketed.

While iron was historically included as part of the trace mineral profile in many feeds, a number of balancers are now explicitly labelled as “no added iron” or “iron-free.”

This reflects a growing recognition that forage-based diets often already provide significant amounts of iron, and that additional supplementation in the UK should mainly be avoided.

As a result, iron inclusion is no longer consistent across balancer formulations. Instead, different products now reflect different approaches, ranging from continued inclusion to deliberate exclusion based on total dietary intake.

(Note: formulation approaches vary between products and over time.)

Hay soaking practices

Another more recent example is hay soaking. Long soaking times, six hours, twelve hours, or overnight, were commonly recommended to reduce sugar levels in hay.

This guidance was widely adopted and became standard practice, often applied as a precautionary approach in the absence of forage testing.

However, as more research became available and practical experience increased, a clearer understanding began to emerge. Both published studies and forage analysis data show that significant sugar reduction can occur within much shorter timeframes.

At the same time, it became increasingly evident that extended soaking carries unintended consequences. Prolonged soaking leads to substantial losses of water-soluble nutrients, including key minerals, and can significantly reduce the overall nutritional value of the forage.

In addition, long soak durations increase the risk of microbial growth and hygiene issues, particularly in warmer conditions, with hay effectively sitting in nutrient-rich water for extended periods.

At Forageplus, our own analysis of forage samples and soak testing supported these findings.

As a result, recommendations began to shift.

Many veterinary professionals and feed companies are now moving toward shorter soaking durations, typically in the range of one to two hours, alongside a growing emphasis on forage testing where possible.

For example, Simple System Horse Feeds (2025) has advised that soaking should be limited to around one hour, noting that extended soaking can result in significant losses of nutrients. This approach allows for more precise management, rather than relying on extended soaking as a blanket solution.

However, as with previous examples, this shift has not been immediate across the entire industry. Some guidance still reflects earlier practices, despite the growing body of evidence pointing in a different direction.

What is now emerging is a more refined and targeted strategy, one that prioritises understanding the forage being fed, using shorter soaking times where necessary, and avoiding unnecessary nutrient loss.

As with iron and fructan, the pattern is consistent. Initial recommendations are broad and cautious, but become more precise as evidence improves.

In some cases, the greatest barrier to change is not a lack of data, but the natural reluctance to move away from established beliefs. Yet in equine nutrition, the priority must always remain the same: to follow the evidence where it leads, in order to support the long-term health of the horse.

Straw Feeding

Straw is often promoted as a practical tool for weight management. It is lower in energy than hay, increases chewing time, and can help extend forage intake, making it an attractive option for reducing calorie intake while maintaining feeding volume.

However, when considered in the context of overall nutrition, a more complex picture emerges.

Straw is not simply a lower-calorie version of hay. It is a fundamentally different feed, consistently low in protein, deficient in key minerals and vitamins, and highly variable in composition. While it may reduce calorie intake, it also reduces nutrient supply.

In addition, real-world data highlights further uncertainties, including mycotoxin risk, microbial contamination, pesticide residues, and variability in sugar and starch where grain residues are present.

This shifts the question from “Does straw reduce calories?” to “What does straw fail to provide, and what risks does it introduce?”

Reducing calories without maintaining nutrient intake can lead to loss of condition, muscle and overall health, particularly in horses already under metabolic or physiological stress.

Straw may have a role in carefully controlled situations, but it is not a direct substitute for forage and should not be used without a clear understanding of its limitations.

As with iron, fructan, and hay soaking, the pattern is consistent. Early adoption of a simplified solution is followed by deeper analysis, revealing a more complex reality.

Whether current enthusiasm for straw feeding will follow the same trajectory remains to be seen, but as data continues to accumulate, recommendations are likely to become more refined and more selective.