🌧️ Rain-Damaged Hay: Safe Feeding for Horses and Cattle in 2025 🐴🐄

By Dr Duncan Houston BVSc

If you’ve ever had a hayfield cut just before a surprise rainstorm, you know the disappointment—and the questions that follow. Can this hay still be fed? Is it safe for horses or cattle? In 2025, understanding the impact of rain on hay quality is essential for both animal health and farm economics. 🌾💧

📉 What Happens When Hay Gets Rained On?

Dr. Brian Pugh from Oklahoma State Extension outlines four main ways rain damages cut hay:

1. 🌿 Leaching of nutrients—soluble sugars, vitamins, and minerals are washed away
2. 🌡️ Prolonged plant respiration—cut plants continue to metabolize, losing energy
3. 🍂 Leaf shattering—mechanical drying (like raking) after rain breaks nutrient-rich leaves off stems
4. 🦠 Microbial degradation—moisture allows fungi and bacteria to digest the hay

These losses can reduce hay’s nutritional value, digestibility, and shelf life—especially in horses and growing cattle. 🧬❌

📊 How Much Nutrient Loss Is There?

According to studies, hay can lose up to:

• ⚠️ 5% of dry matter per inch of rain if left in the field
• ⚠️ 30–40% of digestible nutrients from repeated rainfall and raking

Light rain immediately after cutting causes less damage than prolonged rain on semi-dried hay. Timing matters. ⏱️🌧️

📦 How to Evaluate Rain-Damaged Hay

💡 The only reliable way to know hay quality is through forage analysis. Send a sample to a certified laboratory and ask for:

• 🌾 Crude protein
• 🌿 Neutral Detergent Fiber (NDF)
• 🔥 Relative Feed Value (RFV)
• 💥 Mold or mycotoxin screening (especially for horses)

👉 Horses are more sensitive than cattle—especially to mold, dust, and nutrient imbalances. Always test hay before feeding it to horses. 🐴🧪

🐴 Feeding Rain-Damaged Hay to Horses

If lab results show adequate protein and no mold, it may still be acceptable as part of a balanced diet, especially if:

• 🥕 It’s fed alongside a fortified feed or balancer pellet
• 🚿 It’s soaked briefly to reduce dust before feeding
• ⛅ It’s stored properly and kept dry after baling

🚫 Never feed hay that smells musty, feels damp, or contains visible mold to horses—it can cause colic or respiratory distress. 🧠💔

🐄 Feeding Rain-Damaged Hay to Cattle

Cattle are more tolerant of slight mold or nutrient loss, but rain-damaged hay still needs evaluation. Ruminants can handle lower quality forage IF:

• 💊 Supplementation is provided (minerals or protein)
• 🧪 Hay is tested for energy content and nitrates
• 👀 It is free of mold or spoilage that would reduce intake

For lactating cows or growing calves, more nutrient-dense alternatives may be needed. 🐮🌾

🛠️ Storage Tips to Minimize Loss

Hay that was wet during baling should be stored carefully to prevent further degradation or spontaneous combustion. ✅

• 🏠 Store under shelter with airflow
• 📦 Use pallets to keep off ground
• 🌡️ Monitor temperature—hay baled too wet can self-ignite

🩺 Ask A Vet for a Forage Evaluation Plan

Feeding rain-damaged hay safely depends on testing and strategy. At AskAVet.com, Dr Duncan Houston and team offer:

• 🧪 Forage testing interpretation
• 📋 Ration formulation for horses and cattle
• 📉 Laminitis and mold risk screening
• 📲 Customized feeding calculators for hay blends

🏁 Final Thoughts

Rain may be inevitable, but feeding problems aren’t. With careful testing and adjustments, many lots of rain-damaged hay can still be used safely and economically. 💰🐴

Need a hay quality checklist or lab submission form? Visit AskAVet.com to download yours today 🧪📄