Grazing - Good or Bad??

Spring is approaching quickly and with that comes the flourishes of fresh green grass and the attacks of laminitis. All ages of horses can get laminitis but veterans are more prone to it?

Why do they have sudden attacks of Laminitis?

Research is being carried out into the attacks of laminitis and recent findings have shown that fructans - a form of carbohydrate stored in grass - are likely to be the culprits. Levels of fructans vary in grass an amount depending on weather conditions and other factors, such as the type of grass grown and how it is managed so it isn't surprising that predicting an attack of laminitis can be very difficult.
Dr Annette Longland of the institute of Grassland and Environmental Research (IGER) in Aberystwyth considered this problem recently in a paper she presented to the Third International Conference of Feeding Horses. She came up with a number of points for reducing the risk factors associated with this devastating disease.

What are Fructans?

During photosynthesis, the grass 'fixes' atmospheric carbon dioxide in the presence of sunlight to produce sugar - which is then either metabolised for growth or stored. This stored sugar will be either starch or sucrose and fructans.
There isn't a fixed ratio of sucrose and fructans. When the energy demands of the plant are high, eg.; rapid growth or flower development, sucrose and fructans are used, as energy sources and fructans concentrations will decline. If growth is reduced at a time when photosynthesis continues at a rapid rate, fructans will accumulate.

Why are Fructans a problem to horses?

Unfortunately, there is little information yet on the horse's ability to digest fructans, but there is plenty of research undertaken to suggest that problems may occur.
Studies show that sucrose can be digested down to glucose and metabolised, fructans are likely to pass undigested through the stomach and small intestine to the hindgut.
It is understandable that this is a problem; experts have looked at cereal starch, which passes undigested into the hindgut. The bacteria found there, the by-products of which make the hindgut too acidic, rapidly ferment such starch. When the environment becomes more acid, the 'good' bacteria die - and in doing so they release toxins into the horse's bloodstream. It is there toxins, which are thought to induce diet-related laminitis. "If starch overload can cause laminitis in this way, it is proposed that fructans, which are also rapidly fermented, could also help initiate the onset of laminitis in a similar manner to starch," says Dr Longland

Can we limit the amount of Fructans our horses eat?

It would be very difficult to limit the amount of fructans, but it would be easier to take into account a general management plan:

† Avoid turning your horse out for long spells of grazing in the spring (prior to flower development) and autumn be 'safer' to turn your horse out for longer spells after seed setting if use of unmanaged pastures is unavoidable.

† Considerably more fructans are found in the stem of the grass than in the leaf, the stem being the main storage organ for grass. Because of this, don't graze horses on freshly cut stubble (after a hay harvest).

† Well-managed fields, which are grazed by sheep or cut, will have a high leaf to stem ratio and will contain much less fructans in mid-summer, than if they had been allowe to mature. If the grass is being severely grazed or cut very close to the ground, fructan contents will decline because they are being used to support re- growth.

† Fructan levels fluctuate wildly from hour to hour and unlikely to remain the same over the period of the day. The amount of fructans can be affected by factors such as temperature, light and how many fructans remain from the previous day.

† Try turning your horse out very late at night or early in the morning when light levels are low so very few fructans are produced. Bring them in off pasture by mid-morning.

The type of grass that is grown has a lot to do with the levels of fructans, Perennial Ryegrass often has higher fructan levels than Cocksfoot or Timothy.

It is essential that your horse eats only very small amounts of fructans. To replace part of his grass intake replace with hay, haylage, silage, alfalfa products, sugar beet or cereal straw. These all have lower fructan values.