For most UK horses, winter is the biggest dietary change of the year. Grass growth slows, turnout is reduced and the diet switches from grazing to hay or haylage, often over just a few weeks. Each of those changes affects the microbes in the hindgut that ferment fibre and keep digestion moving. This article explains why winter is hard on the gut and sets out practical steps to keep things steady until spring. It is general guidance from Horse Probiotics, and any concern about a particular horse should go to your vet.
Why winter is hard on the gut
A change of forage
Moving from grass to conserved forage changes what the hindgut microbes are fermenting. A University of Nottingham systematic review in PLOS ONE found that changes in feed, including changes of hay, had the largest body of evidence among management-related risk factors for colic. Batches of hay and haylage also vary through the winter, so the change rarely happens just once.
More time in the stable
The same review found that recent changes in housing were the second best-evidenced management risk factor, with the effect seen within two weeks or less of the change. Stabled horses also move less, and Redwings lists prolonged confinement among the possible stress triggers for colic and laminitis.
Less water
Hay and haylage contain far less water than fresh grass, so a horse on conserved forage needs to drink more to make up the difference. At the same time, water can freeze, buckets get knocked over and some horses seem reluctant to drink very cold water.
Long nights
Horses evolved to eat for much of the day and night. In a long winter night in the stable, a single haynet can run out hours before morning, leaving the gut with a long gap.
Practical steps for winter
1. Make the switch gradually
Start offering hay or haylage while your horse is still grazing, so the hindgut meets the new forage a little at a time. When you move between batches of forage, blend old and new over around two weeks where you can. Our page on diet changes and turnout covers forage changes in more detail.
2. Keep forage available
World Horse Welfare advises providing ad-lib access to good-quality forage at all times, and especially during cold weather. It explains that below about 5°C horses warm themselves partly by eating more forage. For good-doers, it suggests slowing intake with slow feeders or small-holed haynets rather than leaving long gaps. Our article on how much forage a horse needs helps with quantities.
Overnight is where gaps most often appear. Two smaller nets hung in different places, or a net with smaller holes, can make forage last until morning. Weighing nets when you fill them shows exactly how much your horse is getting, which is far more reliable than counting slices or wedges. If your horse finishes everything long before morning, that is a sign to adjust the method or the amount rather than to accept a long empty spell.
3. Encourage drinking
World Horse Welfare advises that fresh water is always available and that troughs and buckets are checked two or three times a day in freezing conditions, with ice broken and removed. Some owners find their horses drink more if the chill is taken off the water. Soaked fibre feeds and dampened feeds add extra fluid, which is useful for horses that drink little.
4. Keep them moving
Turnout, even for a few hours or in a small area, and regular exercise both help. If fields are closed, hand walking or time in a school can break up long periods in the stable.
5. Watch condition under rugs
Rugs hide weight loss and weight gain. World Horse Welfare recommends checking body weight regularly with a weigh tape and fat scoring, removing and readjusting rugs daily to check the horse, and not rugging based on how cold you feel. It advises that horses with a fat score below 2 on its 0 to 5 scale are checked by a vet. Older horses can lose condition quickly in winter, and our page on senior horses covers their particular needs.
6. Keep up with teeth and worm control
Hay needs more chewing than grass. Redwings advises dental checks at least once a year, and an autumn check helps make sure your horse can make the most of its winter forage. Ask your vet or SQP which worm tests and treatments are appropriate at this time of year.
7. Plan for bad weather
Snow, flooding and frozen yards can disrupt routines at short notice. Keep enough forage in stock to avoid a sudden switch to whatever is available locally, and if you do have to change supplier mid-winter, blend the new forage in as gradually as supplies allow. Swapping between hay and haylage counts as a change too, since the two differ in moisture and texture. When fields are closed for a few days, keep feed times and forage as consistent as possible so that the loss of turnout is the only thing that changes.
Where supplements fit
Some owners start a gut balancer before the switch to winter forage and continue through the colder months. That is a reasonable use of a supplement, as long as expectations are realistic: reviews of live yeast and probiotics in horses describe the evidence as mixed, and no product replaces gradual change, forage and water. Our gut balancers guide explains the ingredients, the comparison of powder, pellets and paste covers formats for winter feeds, and the reviews hub assesses individual products from their published information.
Signs to watch this winter
- Fewer droppings, or droppings that are drier and firmer than usual
- Water left untouched in the bucket or trough
- Haynets finished long before morning
- Loss of condition found when rugs are removed
- Dullness or reduced interest in feed
Our article on colic warning signs covers what to look for and what to do while you wait for the vet.