Vitamin E in Winter – A Quick Reminder for Horses on Conserved Forage

Written by Briony Witherow MSc RNutr. FHEA

When grass growth tails off and turnout is limited, many horses move onto conserved forage only (hay or haylage). That’s when vitamin E deserves a second look. Vitamin E is a key antioxidant for muscle and immune function, helping to protect cells from everyday oxidative stress that can rise with training, illness/injury, or higher-oil rations. Fresh grass is normally the biggest contributor of vitamin E in the diet; dried forages contain much less, so winter can quietly create a gap. 

Why it matters

Antioxidants “mop up” free radicals produced during normal metabolism and periods of stress or exercise. They tend to work best in combination (vitamin E alongside vitamin C, selenium and other antioxidant compounds), supporting recovery and overall resilience.

Who’s most at risk in winter?

• Horses with little/no access to fresh grass (stabled or on bare paddocks).
• Horses in moderate–hard work, where oxidative demand is higher.
• Diets with added oil (e.g., vegetable/linseed oil) without matching antioxidant support.

How much vitamin E?

Use bodyweight and workload to check your ration:

• At rest/light work: aim for 1–2 IU/kg BW/day (e.g., 600–1200 IU for a 600 kg horse).
• Moderate–hard work: typically 2000–4000 IU/day.
• If adding straight oil: add 100–150 IU vitamin E for every extra 100 ml oil fed.

Use these figures to help you review whether your current ration is likely to be meeting requirements and whether you need a top-up through winter.

Practical winter checks

• Audit the ration: total up the IU of vitamin E from all feeds/supplements. Compare to the targets above.
• Match to workload and management: conserved forage-only diets commonly run short; training, travel and cold weather can add to oxidative load.
• Think “antioxidant team”, not solo: combining vitamin E with other antioxidants offers synergistic benefits.

Simple ways to close the gap

If your calculation shows a shortfall, consider adding a dedicated vitamin E source through winter. From your range:

• Premier E – 50 g provides ~3000 IU vitamin E alongside complementary antioxidants; a good option for harder work or oil-supplemented diets.
• Selenavite E – 50 g provides ~2000 IU vitamin E alongside complementary antioxidants

Final notes

• Many “general” feeds include some vitamin E, but don’t assume it covers winter needs on hay/haylage alone—especially for working horses or those on added oil.
• Aim for consistent daily intake rather than occasional high doses; review after a few weeks and adjust to workload and season.

By building a small winter vitamin-E check into your routine, you’ll keep muscle function, immunity and recovery on track when grass is scarce and oxidative demands can creep up.