Forage and horses: managing the transition from heatwaves to rainfall
Sciantec
Agriculture
After an unusually hot, dry summer, the return of rainfall may seem like welcome news for horse owners. However, looking at the link between forage and horses and the transition from drought-stressed grass to actively growing pasture requires careful management.
During prolonged dry conditions, grass growth slows as soil moisture becomes limiting. Once rainfall returns, soil microbial activity, root growth and nutrient uptake can increase rapidly, triggering a flush of new pasture growth. This regrowth often differs from drought-affected summer grazing, with changes in moisture content, digestibility, protein levels and overall nutrient composition.
Following rainfall, grasses use stored carbohydrates to support rapid leaf and root regrowth. As autumn progresses, cool temperatures can slow growth rates while sunny conditions continue to drive photosynthesis. When sugar production exceeds the plant’s growth requirements, carbohydrates can accumulate within the grass, potentially increasing the concentration of non-structural carbohydrates in the forage. As a result, the forage available to horses in the autumn may differ substantially from the pasture they grazed during the summer.
Understanding how pasture quality changes during this seasonal transition can help horse owners make informed decisions about grazing management, forage provision and supplementary feeding.
Forage and horses: a summer of extremes
The UK experienced exceptionally dry conditions during July 2026. England and Wales recorded just 4% of their average July rainfall, while Southeast and central Southern England received only 0.7 mm, equivalent to 1% of the regional average. The Met Office described July as the driest on record for both England and Wales.
August brought some rainfall, but totals remained below average across most of the country.
More unsettled weather is now forecast, with areas of low pressure bringing rain and showers across many parts of the UK. However, we must keep an eye on these forecasts, as it’s now predicted that exceptionally stormy and wet weather is on its way.
Following a prolonged period of dry weather, this change may cause grass growth to accelerate, particularly if temperatures remain mild and soil moisture levels recover. The resulting pasture will be more digestible than the drought-stressed grass it replaces, meaning horses may be exposed to a different nutritional profile as autumn progresses.
What happens to grass during a drought?
Grass does not stop functioning during a drought, but it alters how it uses its resources to improve its chances of survival. As soil moisture becomes increasingly limited, the plant prioritises maintenance of essential tissues over the production of new leaves. Growth slows, leaf area reduces, and pasture cover can decline significantly.
These changes affect not only the quantity of forage available but also its composition. As grass remains ungrazed or grows more slowly, plants mature, leading to increased structural fibre and reduced digestibility. This can impact the nutritional value of the pasture, even where some green leaves remain.
Drought can also disrupt the normal balance between photosynthesis and growth. When environmental conditions are sunny, but water availability restricts leaf expansion and biomass production, some of the carbohydrates produced by photosynthesis may accumulate within the plant rather than being converted into new growth. The extent of this response varies with grass species, temperature, sunlight intensity and drought severity.
For horse owners, this means that pasture quality cannot be judged by appearance alone. A field that looks sparse, brown, or heavily grazed may still provide energy through non-structural carbohydrates. However, the digestibility, protein content, mineral availability and moisture content of the forage may differ substantially from those typically expected during periods of active growth.
Why does this matter for horses?
These changes are particularly relevant for horses and ponies that are prone to laminitis, insulin dysregulation, obesity, Equine Metabolic Syndrome (EMS), or other conditions affected by the intake of non-structural carbohydrates (NSC), including sugars and fructans. In susceptible animals, excessive consumption of these carbohydrates can contribute to metabolic disturbances and increase the risk of laminitis
Managing pasture effectively can be challenging because its nutritional composition can change more rapidly than its appearance. Grass that appears sparse may still contain accumulated concentrations of non-structural carbohydrates. Rainfall can encourage a flush of fresh autumn growth resulting in a change in digestibility, moisture content and nutrient composition from the pasture available only a few weeks earlier.
As a result, relying solely on the colour, height or density of the sward can make it difficult to assess the nutritional value of the forage horses are consuming.
What happens when rainfall returns?
When rain follows a prolonged dry period, grass can begin growing again quickly. However, the response will depend on factors such as soil condition, temperature, sunlight, grass species, grazing pressure, and the amount and timing of rainfall.
Fresh regrowth is often younger and contains a higher proportion of water than the more mature pasture available during dry conditions. Because horses consume nutrients on a dry matter basis, changes in pasture moisture can influence the quantity of grazing required to meet nutritional needs.
Current guidance suggests that horses should typically consume at least 1.5% of their bodyweight as forage dry matter each day, meaning that pasture availability is more accurately assessed through dry matter supply than by visual appearance alone.
Forage and horses: why does the transition matter for horse diets?
Forage is the foundation of most horse diets. Its quality influences energy intake, protein supply, fibre levels, digestive health, body condition, and performance.
A flush of new grass growth may be particularly appealing to horses, encouraging them to eat more than usual. If they move suddenly from dry, mature pasture to lush regrowth, their total intake can increase quickly.
For horses at risk of laminitis, obesity, insulin dysregulation or Equine Metabolic Syndrome (EMS), this can be a significant concern. For these animals, maintaining an appropriate balance of energy and non-structural carbohydrates is often a key part of dietary management. Sudden changes in forage, grazing time, or sugar intake can make this more difficult. Even horses that have coped well throughout the summer may need closer monitoring as conditions change.
The transition can also affect broader feeding decisions. When pasture changes rapidly, the forage being consumed may no longer match the diet that was planned earlier in the season. For example, a horse may need less supplementary feed if grass growth increases, while another horse may require additional fibre if drought has left pasture sparse and poor in dry matter availability.
The same applies to hay and haylage. These may be used more frequently during a dry summer, or mixed with fresh grass as turnout conditions change. However, forage quality can vary between fields, cuts, bales, and storage conditions. A previous analysis may not accurately represent a new batch or a different area of pasture.
For horses with specific nutritional requirements, informed decisions are particularly important. Reviewing forage provision, grazing management and body condition during this period can help ensure the overall diet remains aligned with the horse’s needs.
What can we do to manage forage this autumn?
There are several practical steps horse owners can take to manage the transition from drought to rainfall.
- Monitor grazing conditions, not just grass cover
Pasture quality can change rapidly following rainfall, even when the field appears largely unchanged. Fresh regrowth differs from drought-affected pasture in its moisture content, digestibility and nutrient composition. Assess grazing conditions regularly and be aware that the nutritional value of the forage may not be reflected by grass height or colour alone.
- Introduce grazing changes gradually
Where possible, avoid sudden changes in grazing management as pasture begins to recover. Gradual adjustments to turnout time and continued access to suitable forage can help maintain a more consistent fibre intake while allowing horses to adapt to changing grazing conditions.
- Monitor horses closely
Keep an eye on body condition, weight, behaviour, manure consistency and any signs of foot soreness or sensitivity. Particular care may be required for horses and ponies with a history of laminitis, obesity, Equine Metabolic Syndrome (EMS) or insulin dysregulation, as pasture composition can change during periods of active autumn growth. If you have concerns, seek advice from your vet or a qualified equine nutritionist.
- Review the overall diet
As pasture quantity and quality change, supplementary forage and concentrate feeding requirements may need to be adjusted. Rather than basing decisions solely on the amount of visible grass available, consider the horse’s body condition, workload, age, health status and individual nutritional requirements.
- Analyse forage with an accredited laboratory
Forage analysis can provide valuable information about the nutritional characteristics of grass, hay or haylage. Depending on the test selected, analysis may include dry matter, crude protein, fibre, energy, mineral content and water-soluble carbohydrates.
Used alongside professional nutritional advice, these results can help support more informed feeding decisions and identify differences between forage sources throughout the season.
How Sciantec can help
Laboratory analysis gives you a clearer picture of what your forage is delivering. By measuring key parameters such as dry matter, energy, protein, fibre, and sugars, analysis can help you make informed decisions about grazing, rationing, and supplementation, while maximising the value of your homegrown forage.
Our forage services include:
- FN02 – NIR Fresh Grass
- FN04 – NIR Hay/Haylage
- FM10 – Forage Dietary Minerals
And more, depending on your requirements.
References
https://www.metoffice.gov.uk/blog/2026/july-2026-weather-stats-a-regional-breakdown
https://www.metoffice.gov.uk/blog/2026/august-2026-weather-stats-a-regional-breakdown
https://www.metoffice.gov.uk/blog/2026/week-ahead-rain-ahead-before-a-potentially-drier-weekend
Geor, R.J. (2010), ‘Current concepts on the pathophysiology of pasture-associated laminitis’, Veterinary Clinics of North America: Equine Practice, 26(2), pp. 265-276. Av: https://www.vetequine.theclinics.com/article/S0749-0739(10)00046-5/fulltext
Longland, A.C. and Byrd, B.M. (2006), ‘Pasture nonstructural carbohydrates and equine laminitis’, The Journal of Nutrition, 136(7 Suppl), pp. 2099S-2102S. https://jn.nutrition.org/article/S0022-3166(22)08398-5/fulltext
MSD Veterinary Manual (2024), Laminitis in Horses. https://www.msdvetmanual.com/musculoskeletal-system/disorders-of-the-foot-in-horses/laminitis-in-horses
Merck Veterinary Manual (2025), Equine Metabolic Syndrome. Available at: https://www.merckvetmanual.com/metabolic-disorders/equine-metabolic-syndrome/equine-metabolic-syndrome
Rutgers New Jersey Agricultural Experiment Station (2022), Non-structural Carbohydrates and Equine Warm-season Grass Pastures (FS1340). https://njaes.rutgers.edu/fs1340/
CAFRE (2021), Managing forage intake in stabled horses. College of Agriculture, Food and Rural Enterprise. https://www.cafre.ac.uk/2021/01/29/managing-forage-intake-in-stabled-horses/
Wilson, L. (2022), Feeding a horse forage: why this alone often will not provide all the vitamins and minerals a horse needs in their diet. Your Horse. https://www.yourhorse.co.uk/horse-care/top-forage-feeding-tips/
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