Feeding during seasonal changes

There are some key considerations for feeding your horse during the change of seasons. Equine nutritionist LARISSA BILSTON explains.

From the warmth of spring and summer to the crispness of autumn and the chill of winter, horse owners must adapt their feeding strategies to ensure optimal health and performance. Changes in temperature, pasture quality, and metabolic considerations require thoughtful nutritional adjustments.

Climatic regions should also be considered, as the transition from the wet to dry season in the tropics requires different management strategies compared to the changes across all four seasons in temperate regions. Here’s what every horse owner should consider when managing feeding programs during these transitional periods.

Seasonal nutritional shifts

The forage available to horses varies throughout the year because pasture growth and maturity changes in response to environmental conditions. Spring and autumn are particularly challenging seasons because they bring fluctuations in temperature and grass growth, and can impact metabolic sensitivities when plants are high in carbohydrates. To navigate these changes successfully, horse owners must assess forage availability, balance nutrient and sugar intake, and monitor their horses for signs of dietary imbalances.

Temperate zones

Adjusting forage availability: During a hot, dry summer when grasses mature and dry off, most horses will have been transitioned onto a quality grass or meadow hay to supplement forage levels. As the weather begins to cool and autumn rains bring fresh grass shoots, continue to feed hay at an appropriately reduced rate as the gut adapts to the change in forage quality. This helps to maintain gut health and minimise scouring. Grass growth will slow and become less nutritious from mid-autumn and over winter, so horses will once again benefit from increased hay supplementation to ensure adequate forage intake.

Maintaining healthy body condition: As grass growth increases in early autumn, control the size of hard feeds to maintain a healthy body condition. Some horses may require only a slight reduction in hard feed, while easy keepers will need only a small quantity to carry supplements with the essential vitamins, minerals needed for optimal health.

As temperatures cool, horses require more calories to maintain body heat. For horses in light work, forage may provide enough calories, but many Thoroughbred types and hard-working or older horses may need additional energy sources with more hay and a larger hard feed over winter. It is better to make frequent small changes to the size of meals than to wait until drastic weight gain is required.

Considerations for metabolic conditions: Horses with metabolic conditions such as equine metabolic syndrome (EMS) or insulin resistance (IR), including some with Cushing’s disease, are prone to laminitis during seasonal transitions. Grass sugar levels are naturally more concentrated in young shoots and after frost, increasing the risk of laminitis.

Metabolic horses require careful management to avoid the high carbohydrate grasses that increase a blood insulin response and trigger laminitis. Recommended management strategies include reducing total intake with the use of grazing muzzles, strip grazing and removal from grass onto track systems or loafing pads. These strategies aim to replace high sugar, high starch grass with low carbohydrate teff or rhodes grass hay (which may be soaked to further reduce sugar levels).

When feeding laminitis-prone horses, in addition to managing forage consider adding DHA omega-3 and specific prebiotics designed to improve insulin sensitivity as part of your risk management plan.

Tropical and subtropical zones

Adjusting forage availability: Pasture grasses grown in regions with warm, wet summers are most active during long summer days. As days begin to shorten in late summer and temperatures drop in autumn, tropical grasses mature, go to seed and decline in nutritional value. At this time, horses need good quality forage, mainly in the form of leafy grass hay, with a small proportion of legume hay (such as lucerne), to provide enough protein and total intake for good health.

If pastures contain any temperate species such as ryegrass, horses with metabolic conditions such as EMS or IR need very careful management during autumn to reduce laminitis risk (see previously mentioned management strategies).

Maintaining healthy body condition: As grasses become lower quality and less abundant, some horses will need more calories than their grass and hay can provide. Increase the size of hard feeds in response to weight loss but always ensure free choice hay is available for underweight horses.

When needed, increase the level of energy (calories) in the diet with choices such as a cereal grain (oats or barley), a legume grain (lupins), a superfibre (beet pulp, soy hulls or lupin hulls), or oil – or any combination of the above. When choosing the most appropriate grain or energy source, consider the horse’s teeth, their digestive efficiency and how much time and energy you can dedicate to meal preparation. Whole oats can be fed raw, but other cereal grains such as barley and oats must be fed in a cooked form – boiled, pelletised, steam-flaked or micronised. Some superfibres require soaking and whole lupins are also best soaked to soften the seed coat.

The amounts of hard feed required depends on horse size, level of activity or breeding status, amount of energy provided by roughage, and the individual horse’s metabolism.

Considerations for hay-reliant horses: Fresh grass is rich in many vitamins, which do not store well once grass is cut and cured for hay. Vitamins, especially A, B and E should be supplemented when hay is the major roughage source. Similarly, omega-3 fatty acids in fresh grass do not store in hay. These natural fats are responsible for providing anti-inflammatory balance in the immune system, countering the pro-inflammatory omega-6 oils in hay and hard feeds. To tip the omega 3:6 ratio back into balance, there are various ways of supplementing omega-3 fatty acids including fish oil, certain types of algal powder, chia seeds and linseed (flaxseed) seeds and oils.

When horses eat a lot of hay rather than grass, they will drink more because hay contains much less water than fresh grass, so be sure to keep water troughs full of clean, cool water. It is also important to ensure enough salt is fed to keep water intake up and avoid impaction colic. Salt can be sprinkled through a large bale of free-choice hay, as well as added to each individual meal.

Low quality hay with a high proportion of stem and little leaf can cause horses to scour. If this occurs, replace up to 30% of the daily intake with lucerne hay, or increase grass hay quality by sourcing leafy hay. Increase electrolytes and add a probiotic containing S. boulardii live yeast to improve the gut health of horses with diarrhoea.

General best practices

Regardless of the season, these best practices help ensure a smooth dietary transition and optimal horse health:

• Make changes gradually: Any dietary adjustment should be made slowly over 7 to 14 days to prevent digestive upset. If possible, introduce horses to green grass paddocks gradually, beginning with less than an hour once or twice a day and slowly increase. Sudden changes in feed or forage can disrupt the gut microbiome and lead to colic or diarrhea. Horses with gut sensitivities who scour or develop fecal water syndrome with significant changes in pasture, can benefit from supplementation with probiotic live yeast (especially Saccharomyces boulardii and cerevisiae) or hindgut buffers to help maintain a more stable hind gut pH.
• Monitor body condition regularly: Seasonal changes in pasture quality and availability can cause fluctuations in body fat. Use a body condition scoring system to track weight and adjust feed as necessary. Small, frequent changes are better than fewer, large dietary adjustments.
• Balance nutrients properly: Ensure that horses receive a well-balanced diet with appropriate levels of fibre from forage, the primary energy source; proteins for muscle maintenance and repair from leafy forage, legume grains or forage; fats for omega-3 balance and to add energy without excess carbohydrates; vitamins and minerals essential for immune function, hoof health, and overall well-being; and electrolytes, because even in cold weather horses still need at least 7g of salt per 100kg bodyweight, which encourages them to keep drinking.
• Consult an expert: An equine nutritionist or a veterinarian with a special interest in nutrition can help fine-tune feeding plans based on individual horse needs, workload, and metabolic conditions. This can ultimately save on costs through a reduction in unnecessary supplements, improved ‘fuel efficiency’ and better immune function.

Feeding horses during the transitional seasons of autumn and spring requires careful planning and proactive management. By understanding the unique challenges of each season, whether it’s maintaining body weight or preventing laminitis, owners can ensure their horses remain healthy, happy, and well-nourished. Through gradual dietary adjustments, close monitoring, and a well-balanced feeding regimen, horses can thrive through seasonal changes.

Larissa Bilston, BAgrSc (Hons) is the Equine Nutritionist for Farmalogic.