Fructan in pasture grass – Grazing correctly

Many horse owners are already aware that, in horses with a sensitive metabolism, consuming too much sugary pasture grass can trigger an episode of laminitis, which can lead to a life-threatening condition. Fructan is one of the substances suspected of causing this.

What are fructans?

Fructans are chains of fructose molecules. These long-chain carbohydrates are a short-term form of sugar storage, primarily in the plant’s stem. Long-term energy storage, on the other hand, is found in the plant’s leaves, where it is stored in the form of starch. The sugar serves as a source of energy and enables the plants to grow. Intensive sunlight leads to increased photosynthesis, resulting in greater sugar production. Depending on the weather, the sugar is either used up or stored in the form of fructan. If, under certain weather conditions (cold, drought), the plant is unable to grow, it stores the sugar in the form of fructan. The fructan content in the plant depends on a variety of factors.

Factors that have an influence:

• Plant species or the grass composition of the pasture
• Time of day
• Season
• Growing season
• Climate (temperature)

Sunny days following nights of frost, as we have seen in recent days, are particularly dangerous! If the temperature rises during the day, growth occurs and fructan levels fall. However, if it remains cold, higher fructan levels can be expected throughout the day. In the literature, 6 to 10 degrees Celsius is regarded as the critical temperature threshold. However, this depends on whether the temperature was actually measured at ground level.

As a general rule:

• In particular, do not let horses with pre-existing metabolic conditions (e.g. laminitis, EMS, ECS/PPID) out into the paddock on frosty nights and sunny mornings.
• Ensure that grazing is introduced gradually.
• Support the gut flora with supplementary feed: e.g. Irish Mash, Glyx Mash, yeast culture, Brandon plus medigest.
• Tall meadows may be safer than mown or grazed meadows where fructan-rich blades of grass are growing back fresh. Furthermore, stressed grass produces more fructan.
• It is not only the fructan content that matters, but also the amount consumed. For at-risk horses and those that eat very readily, feeding restraints or muzzles can limit their total intake.
• Similar weather conditions prevail not only in spring but also in autumn, which can result in higher fructan levels in the grass. In addition, towards the end of the grazing season, pastures are usually well grazed, meaning that higher fructan levels are to be expected in any case.

Allow plenty of time for the grazing period. This usually takes around four weeks, during which time the amount of pasture grass consumed is gradually increased.

• 1–4 days                 5–10 minutes in the afternoon
• Day 5–9                 10–25 minutes in the afternoon
• 10–14 days             25–45 minutes in the afternoon
• Day 15–19             20 minutes in the morning & 45 minutes in the afternoon
• Day 20–24             30 minutes in the morning & 1 hour in the afternoon
• 25–30 days            1.5–2.5 hours spread across the morning and afternoon
• From the 5th week onwards      2–4 hours spread across the morning and afternoon
• If the duration is 6 hours or more, the horses can usually be left outside all day