Fructans and pasture management
Fructan has been a frequently heard term in the horse world in recent years. Too much fructan in the ration causes hoof confinement. The moment of grazing, the fertilization of the grassland and insight into the composition of the grass or hay are important in preventing too much fructan in the ration.
Until recently, it was thought that hoof confinement was caused by proteins in the grass. However, recent research has shown that too high a level of fructan is the main cause of this ailment. In 2016, Professor Christopher Politt of the University of Queensland investigated the relationship between fructan and hoof bondage. In an experiment he fed 7.5 grams of fructan per kilo of body weight to horses. All horses were hoofed within 48 hours. This established conclusively that fructan is one of the culprits. But what exactly is fructan? How is it made in grasses and how should you handle it in terms of nutrition?
Grasses produce different carbohydrates during photosynthesis (see box). Fructan is one of these carbohydrates and acts as an energy source for grass. It ensures the growth of the plant. Fructan is produced during the day and used at night. The amount of fructan in grasses can vary greatly: per type of grass, per season and per day. The fructan content is highest at the end of the afternoon / early evening. However, this rule of thumb cannot always be used because the content also depends on:
- Nutrients in the soil
- Crop stage
For all these processes, there is no mechanism that stops the production of fructan. Grass produces fructan as long as it can. The moment that all preconditions are correct, fructan is converted into other building materials.
Sunlight, or actually its intensity, is important for the photosynthetic process. The more intense the sunlight, the better the photosynthesis. This means that more fructan can be created.
The temperature is important for the fructan content due to two processes. Firstly, grass does not grow at low soil temperatures, but it does make it fructan. The fructan that is produced during the day is then used at night. Secondly, at very low temperatures, fructan acts as "antifreeze" and as a result the content increases even further.
Nutrients in the soil
With a shortage of nutrients in the soil, grass cannot grow to its maximum, but the production of fructan continues. In addition, it is important to realize that each nutrient has its specific function.
Insufficient rainfall deceases plant growth. Under dry conditions, grass prepares itself to form seeds and fructan is produced. Fructan accumulates because the grass no longer grows. The grass will also age quickly and the dry matter content (the part that contains all the nutrients) will increase.
The crop stage causes differences. Young grass has more room for fructan and old grass that goes to seed, grows less. In both cases, the fructan content in the grass increases. The stage in between grass grows well and consumes its fructan.
There are types of grasses on the market that contain much less fructan, the so-called 'horse mixes'. These consist of a mix of, for example, timothy, field meadow grass and red fescue.
In general, grass contains more fructan in spring and autumn. Spring because the nights are still cold, and autumn because the grass is outdated, many nutrients in the soil are released together and because of the colder temperatures at night.
Download the whitepaper 'Fructans and pasture management' to read the full article and find out what you can do to manage fructane rich pastures. You can download this article at the top of this page.