Feed Materials In Focus – Forage Management to Reduce the Risk of Health Problems



For most of us there are clear signs that spring/summer is on the way. This is good news as many owners will start to think about increasing turnout time for stabled horses. However, spring and increased grass growth bring a few potential problems for domesticated horses. 


This is one of the basic rules of feeding horses to avoid GI problems! In the same way that you should not switch from one hay straight on to another (but gradually mix the old and increasing amounts of the new for 10-14 days) avoid making sudden changes from hay/haylage to pasture as this can be a risk for COLIC and/or LAMINITIS due to disturbance in hindgut bacteria in particular. So as an example, if your horse is currently stabled with 8 hours turnout on poor pasture, as the grass starts to flourish it may be sensible to significantly reduce time at pasture or consider other ways of reducing intake (e.g. grazing muzzles, strip grazing, etc) for several weeks and allow the pasture intake to increase gradually. The highest risk is likely to be for horses that are prone to colic or have previously had laminitis, but turning any horse straight out onto fresh pasture for long periods straight from being stabled and/or on winter pasture is a big risk. Feeding a high dose of a protected live yeast probiotic has been shown to help reduce GI disturbances due to forage change. 


As with kids and sugar rush, the high sugar content and increased energy intake from fresh pasture compared with hay can lead to unwanted changes in behaviour. Look at any horse Facebook group and you will see the posts start to appear on this topic as the grass comes through. Another good reason to think about managing the transition from primarily hay to pasture or poor pasture to new growth in spring. 


Great Britain has the highest incidence of grass sickness in the world and the disease occurs in most areas of England, Wales and Scotland; eastern counties being particularly at risk. Most cases are seen in April-July with a peak in May – when new grass growth occurs. Support of the hindgut microbiome may help reduce risk and the use of probiotics has been suggested by the Equine Grass Sickness Fund. Further information on EGS is available here: http://www.grasssickness.org.uk/advice/grass-sickness-in-horses/ 


Horses prone to tying-up or PSSM are best managed on low carbohydrate (starch, sugar) diets. New growth grass is much higher in carbohydrates, especially sugars. The sugar content of the grass will normally be higher on very sunny warm days. In addition, sugar content tends to rise during the day (in relation to sunlight), peaking in the afternoon/early evening. 


Assess the risk to your horse. If your horse is a good doer, overweight, EMS/PPID/Cushings, has a history of colic, tying-up, PSSM, grass-sickness and or laminitis, then new spring grass represents a significant risk. If the risk is high, you can do nothing and accept the risk or if your horse is at livery you can speak to the owner/manager – if they refuse to do anything you can accept the risk or move your horse somewhere else. 


Be alert to sudden or rapid new grass growth as this can be a risk for colic, laminitis, tying-Up (RER), PSSM and grass sickness.  

Manage the transition from primarily stabling and/or turnout on poor grass to increased turnout on new growth carefully. 

Turnout overnight (8pm to 8am) when the grass sugar content is lower instead of during the day. Horses are also less active overnight and forage intake will usually be less than during the day. 

Reduce turnout time. 

Use a grazing muzzle – http://www.bhs.org.uk/…/newc-grazing-muzzle–download-final… 

Consider a high dose protected live yeast probiotic. 

Restrict grazing area e.g. using electric fencing. 

Cut the area the horse is going to graze and remove the cut forage. 


About Author

Dr David Marlin is a physiologist and biochemist who has worked in academia, research and professional sport. He has worked in the equestrian and veterinary world and in human sport, healthcare, medicine and exercise science. In 1989 David obtained his PhD from the UK’s leading sports university, Loughborough University following a four-year study on the responses of Thoroughbred racehorses to exercise and training, undertaken at the renowned Animal Health Trust in Newmarket. You can read David's full biography in the Our Website section.