Horses were born to eat grass. For horse owners, pasture is the most natural and economical way to feed horses, reducing the need for hay and commercial feeds. With the right advice on grass species, planting, fertilisation, and grazing management, you can maintain productive pasture all year round.

Know your grass species

A recent survey of over 4,000 Australian horse owners found that 34% don’t know the predominant grass type in their paddocks (see Figure 1).

Grass species are broadly categorised as:

Cool-season grasses (grow best in cooler months)
Warm-season grasses (thrive in hot, humid climates; peak growth in summer at 20–32°C)

Common warm-season grasses:
Warm-season pastures include grasses such as buffalo, kikuyu, couch, Rhodes, setaria, paspalum, and panic, as well as many native species and are widespread throughout Queensland, Northern New South Wales, and parts of Western Australia.

**Figure 1: Predominant pasture species in Australia (Courtesy Claudia Macleay and Petra Buckley, School of Animal and Veterinary Science, Charles Sturt University).**

Oxalates and Mineral Deficiencies

Grasses are typically low in calcium and high in phosphorus. This means that even grasses and hays without high oxalate levels can still lead to calcium deficiency in horses. In addition, pastures often lack other essential minerals such as zinc, copper, selenium, iodine, and salt, making supplementation important for horses grazing year-round.

Understanding Oxalates in Plants

While most plants contain some oxalates, certain subtropical grasses have especially high levels. Oxalates can affect horses in two main ways:

Calcium oxalate: This form is insoluble and passes through the digestive system without being absorbed. Over time, it can contribute to calcium loss and potentially lead to osteoporosis.
Soluble oxalates (such as magnesium and sodium oxalates): These can bind to dietary calcium, reducing its absorption. In older horses, long-term grazing on high-oxalate pastures can increase the risk of kidney failure.

Supplementation

To support horses grazing on pasture, provide a supplement with both organic and inorganic calcium and minerals often lacking in pasture.

Protein and amino acid supplementation are also important, especially for aged, pregnant, and growing horses. As summer progresses and grass matures, protein levels decline. A pasture balancer, like Jenquine all-4-feet®, supplies essential amino acids and minerals that can help meet these increased nutritional needs and maintain your horse’s health year-round.

Grazing systems and management

Rotational grazing is the most effective way to use available forage and reduce spot grazing:

Start grazing when pasture is 15–20cm long.
Move horses when grazed down to 7–10cm.
With three areas, horses graze one for 14 days, then rest pasture for 28 days.

Making the Most of Rapid Forage Growth

When pasture is growing rapidly, one challenge is ensuring all the available forage is used efficiently. While adding more horses might seem like a solution, it can quickly lead to overstocking and management issues. A more sustainable approach is to divide your paddock into a greater number of smaller areas, allowing horses to graze each section for just 3-5 days. As summer transitions to autumn and grass growth slows, you can increase the size of each grazing area and reduce the number of sections accordingly.

Managing Grazing Time to Prevent Laminitis

Horses naturally graze for 12-16 hours a day, but unrestricted access to lush pasture, especially in spring and summer, can increase the risk of laminitis. To help manage intake:

Confine horses from mid-morning (when grass sugar levels rise sharply) until several hours after sunset (when sugar levels drop).
If confinement isn’t practical, consider fitting horses with a grazing muzzle for part or all of the day to limit grass intake and help control weight gain.

These strategies help balance pasture utilisation with your horse’s health and wellbeing.

Small acreages: special challenges

Managing horses on small or agistment properties, especially those located near urban areas, presents unique challenges. Often, the available land is insufficient to provide adequate pasture, even with optimal management. This can lead to persistent issues such as:

Weed invasion
Soil erosion
Dust problems
Soil compaction
Salinity
Nutrient imbalances

Overgrazing poses a significant risk, leading to further erosion, compaction, and weed infestations. While larger farms can more easily implement sustainable grazing systems, these solutions are more challenging for smaller properties.

Long-Term Solutions

Despite these obstacles, excellent resources are available to help small property owners achieve long-term benefits from sustainable land use. With the right guidance, it’s possible to improve both the economic viability of horse ownership and the overall appearance and health of your property.

Weeds and Poisons

Maintaining healthy grass growth requires ongoing effort, and unfortunately, weeds and toxic plants can quickly invade paddocks, reducing grass coverage and posing risks to horse health. This challenge is especially pronounced during unusually dry summers, when paddocks are more vulnerable to invasion by weeds and noxious plants, some of which are high in sugar and/or toxins.

Horses are notorious for nibbling, grazing, and scuffing up the paddock, which leaves bare patches of soil that are easily colonised by weeds. In addition to well-known dangers like ryegrass staggers, there are other threats from fungi and plant toxins.

Common Pasture Hazards:

Buttercups: Contain toxins that can cause gastric inflammation and colic. Horses usually avoid them due to their bitter taste, but if the paddock is overrun, they may have no choice but to graze on them.
False dandelion (flatweed): Can cause stringhalt symptoms.
Pennyroyal: Carries liver and neural toxins.
Lupins: Various types exist; sweet, white lupins have lower tannin levels than purple varieties but can still cause liver damage.
Ragwort: Flowers from late January; seeds remain viable for up to 16 years and spread easily via wind, water, animals, equipment, and contaminated hay. Ragwort is bitter and usually avoided by horses, but unlike buttercup, its toxins persist in hay and silage, and palatability increases when dry, making it a hidden threat.

Essential Pasture Maintenance

To keep your paddocks healthy and safe for horses, regular maintenance is key. Every paddock should undergo:

Soil testing to monitor nutrient levels and identify deficiencies.
Appropriate fertilising to support robust grass growth.
Harrowing to return nutrients to the soil and break up manure.
Targeted spraying for weeds and toxic plants to prevent harmful invasions.

Many symptoms caused by weed toxins can mimic those of ryegrass staggers or excess sugar intake. That’s why it’s essential to thoroughly inspect your paddocks; don’t assume the problem is immediately apparent. Walk your paddocks regularly and learn to identify both weed and grass species. This proactive approach helps you catch issues early and maintain a safe, productive pasture for your horses.

Summer’s Impact on Worm Control

The good news for horse owners is that summer’s hot, dry conditions are tough on worm larvae. After worm eggs hatch, most larvae migrate to within a 15cm radius of the manure pile. In the summer, these larvae survive for only a matter of hours, whereas in cooler, wetter seasons like winter and spring, they can persist for weeks.

To make the most of these seasonal advantages, speak with your veterinarian about adapting your worming programme for summer pasture conditions. Tailoring your approach can help keep your horses healthier and reduce parasite risks.

Conclusion

Pasture is the most economical way to feed horses, costing up to four times less than hay and 8–15 times less than commercial feeds. By understanding grass species and practising effective pasture management throughout the changing seasons, climate, and weather, you can prevent paddocks from becoming horse-sick or degraded, and ensure your horses enjoy healthy, nutritious grazing year-round.

Useful Resources

A wealth of information is available to help you tailor pasture management to your local conditions. By staying informed and proactive, you can maintain a safe and productive environment for your horses throughout the year.

AgriFutures Australia: Plants Poisonous to Horses An Australian Field Guide

References

Macleay, C and Buckley P (2019) Poor pasture management results in Australian horse owners using expensive daily supplementary feeding. © Proceedings of the 2019 Agronomy Australia Conference, 25 – 29 August 2019, Wagga Wagga, Australia © 2019 www.agronomyaustralia.org/conference-proceedings

Dr Jennifer Stewart
BVSc BSc PhD Equine Veterinarian and Consultant Nutritionist

Summer Pasture