We all love the idea of our horses out grazing green pastures, especially after a hard winter where your horse may have spent a lot of time stabled. With good energy, fibre and micronutrient levels, grass offers excellent nutrition, but if your horse hasn’t had access to it for a while, going back out in the field can come as a shock to the system. Lisa Elliott - MSc – nutritionist at Castle Horse Feeds shares some tips and guidance on re-introducing your horse back to pasture safely. 

horse at pasture
Consider your horse’s digestive system 
The digestive system houses a delicate balance of beneficial hindgut microbes that break down forage through fermentation and convert it into a usable source of energy for your horse. These microbes become adapted to your horse’s current diet and are, therefore, conditioned to fermenting whatever type of hay or haylage is fed.  This creates equilibrium and stability within the microbial population, which is beneficial for your horse’s health. These adaptations take time to change, so to protect digestive health, you need to slowly transition your horse back to grazing. 
Sudden changes in forage sources, especially to grass which can have a very different water and carbohydrate profile to hay, can result in microbial imbalances or ‘dysbiosis’ which can lead to hindgut acidosis and potentially colic.  Research has indicated that changing suddenly between forages is a greater risk for colic than changing between different feeds, so it’s important to minimise this. 
Fresh grass can often contain higher levels of sugar than hay and if consumed in too great a quantity this can overwhelm the small intestine and end up in the hindgut where it is fermented rapidly.  This fermentation can result in a build-up of gas and lactic acid, which can result in digestive upset and could ultimately lead to Pasture Associated Laminitis (PAL). Gradually re introducing your horse to grass will help reduce the amount of sugar consumed and minimise the potential for digestive disturbance. 
The amount of sugar in some grasses can cause blood glucose and insulin fluctuations, leading to increased levels of circulating glucose and insulin and increasing the potential for Insulin Dysregulation (ID) – a risk factor for laminitis.  Re-introducing your horse back to grass slowly will reduce the potential for excessive consumption and allow a gradual adaptation to sugar levels to help keep these fluctuations to a minimum.
Take Time 
Slow and steady is key and transitioning your horse to being back out at grass safely takes time.  Ideally, you should begin with short periods of grazing and build it up from there, so start by grazing your horse about 15 minutes per day.  After a few days you can start increasing this by an extra 15 minutes per day until your horse has adjusted to a 4-5-hour period of grazing and then extend this to continuous access. 
Provide additional forage 
Putting the same hay or haylage you have been feeding out in the field can help initially buffer the effects of the grass and promote a more gradual transition. Offering other forages alongside pasture grazing can help increase microbial biodiversity and stability to promote good digestive health. 
Support Beneficial Microbes
A healthy population of beneficial microbes is essential to help negate the effects of a change in diet when re introducing to your horse to pasture.  Yeast based prebiotics have been shown to help nurture and stimulate the growth of beneficial bacteria, so ensuring your horse is receiving good levels of these can further help ensure a smooth transition. 
By being mindful of the potential problems associated with putting your horse back out to pasture and taking steps to manage this process correctly, you can help your horse enjoy the benefits and pleasures of eating grass, whilst preserving digestive health. 
If you have any questions about how to create the best diet for your horse, email This email address is being protected from spambots. You need JavaScript enabled to view it. or call 01497 570345. See for further information and to sign up for free nutrition news and insights.