Vet Guide to Forage & Ration Analysis for Horses 2025 🐴🌾

By Dr Duncan Houston, BVSc

Horses rely heavily on forage for nutrition, digestion, and overall wellbeing. But how do you know if your hay is good enough—or if your horse’s diet needs supplementation? 🤔 In 2025, equine nutrition science gives us incredible tools to evaluate hay quality and create balanced rations. In this vet-approved guide, Dr Duncan Houston breaks down how to start with a **complete forage analysis**, interpret results, and build a nutritional plan tailored to your horse’s specific needs. 💡🐎

1. Why Forage is the Cornerstone of Every Horse’s Diet 🌾

Forage—including hay and pasture—makes up the bulk of a horse’s diet. It fuels the microbial ecosystem in their gut, supports natural behavior (chewing, grazing), and provides vital energy and fiber. Every horse, no matter the breed or work level, should receive at least:

• 1% of body weight in long-stem forage per day ➡️ That’s 10 lbs (4.5 kg) for a 1,000 lb (450 kg) horse.
• Ideally closer to 1.5–2.5% depending on work level, body condition, and metabolism.

Without adequate roughage, horses may develop ulcers, colic, behavioral problems, and nutritional imbalances. But quantity alone isn’t enough—**quality matters too.**

2. What is a Forage Analysis? 🧪

A forage analysis is a laboratory test that measures the nutritional content of hay or pasture. It’s the first step in ration formulation and helps determine whether your horse’s basic dietary needs are being met. Core values tested include:

• Digestible Energy (DE): The amount of usable energy (Mcal/kg or Mcal/lb).
• Crude Protein (CP): Needed for muscle, enzymes, hormones—measured in %.
• Dry Matter (DM): The portion of hay that isn’t water—nutrient calculations are based on this.
• Acid Detergent Fiber (ADF): High values = low digestibility (older, stemmy hay).
• Neutral Detergent Fiber (NDF): Total plant fiber—impacts satiety and intake.
• Crude Fat: Energy-dense macronutrient, often low in forage (~1.5–3%).
• Macro-minerals: Calcium, phosphorus, magnesium, sulfur.
• Trace minerals: Zinc, copper, selenium, manganese, iron, etc.
• Vitamins: Vitamin A, E, and sometimes D or B complex (optional).

These values reveal whether your hay is suitable for young horses, seniors, broodmares, or performance athletes—or whether supplementation is necessary. 📊

3. When and How to Perform a Forage Test 🧬

Here’s how to make sure your test provides reliable and usable data:

✅ Timing

• Test before purchasing large loads of hay 🛻
• Test every new cutting or batch (if feeding from different suppliers)
• Annually for stored hay or pasture if used consistently

🔍 Sampling Procedure

• Use a hay corer (not flakes by hand!) to collect samples from 10–20 random bales
• Mix samples in a clean, airtight bag and freeze or refrigerate until shipped
• Send to a certified lab (e.g., Equi-Analytical, Dairy One)

💲 Cost

• Basic forage analysis starts at $30–$50 USD per test
• Advanced mineral panels or digestibility tests may cost more, but offer deeper insights

4. Understanding Key Nutritional Metrics 📈

4.1 Digestible Energy (DE) 🔥

The amount of energy the horse can absorb. Requirements vary:

• Idle 500 kg horse: ~16–20 Mcal/day
• Light work: 20–25 Mcal/day
• Moderate-heavy work: up to 35–40 Mcal/day

4.2 Crude Protein (CP) 🍗

Needs vary by age and workload:

• Maintenance: 8–10%
• Light work: 10–12%
• Broodmares & growing horses: 12–16%

4.3 Fiber (ADF & NDF) 🌿

• ADF: Ideal range 30–35% for digestibility
• NDF: Ideal 40–55%—higher values reduce intake

4.4 Minerals ⚖️

Pay attention to:

• Calcium to Phosphorus Ratio: Aim for 1.5:1 to 2:1
• Selenium: Often low—essential for muscle function
• Magnesium, Zinc, Copper: Trace deficiencies impact coat, joints, and immunity

5. Balancing the Ration 🧩

Once you know what’s in the hay, compare it to your horse’s needs (based on age, weight, use, and condition). If shortfalls exist, you can supplement accordingly:

➡️ Examples

• Low protein? Add alfalfa pellets or a balancer pellet
• Low energy? Add beet pulp, grains, or rice bran
• Low selenium/zinc? Add trace mineral supplements

Dr Duncan Houston notes: “Always fix forage first. Only then does it make sense to fine-tune with concentrates or supplements.” 🧠

6. Why Consistency in Hay Matters 🧺

Buy large quantities from the same supplier when possible. Hay from a single cutting ensures consistency in nutrition and reduces the risk of digestive upsets. If you must buy in small batches:

• Only buy from growers who provide forage analysis
• Blend new hay with old gradually over 7–14 days

7. Risks of Poor-Quality Hay 🚫

• Mold and Dust: Can cause respiratory illness or colic
• High ADF/NDF: Leads to poor digestion and “hay belly”
• Imbalanced minerals: May stunt growth or impact hoof and coat health

Don’t be fooled by green color alone—only analysis tells the full story. 📋

8. Working with a Vet or Nutritionist 🧑‍⚕️

A veterinarian or equine nutritionist can help interpret lab results and build a custom plan. This is especially important for:

• Horses with medical conditions (e.g., EMS, PPID)
• High-performance horses
• Broodmares, foals, or seniors

Dr Duncan Houston recommends an annual nutrition review to ensure your plan remains effective.

9. Case Example: Rebalancing with Science 🎯

A 10-year-old Quarter Horse gelding was losing topline and showing signs of dull coat and lethargy. Forage analysis showed:

• Low DE (0.78 Mcal/lb)
• Crude protein 7.5%
• Low selenium and copper

With guidance, the owner added alfalfa pellets, a mineral supplement, and switched to a better hay batch. Within 8 weeks, the horse’s topline improved, and energy levels normalized. 🐎

10. Final Tips for Forage Success 💡

• 📦 Store hay in a dry, well-ventilated area to prevent spoilage
• 📅 Label hay by date and supplier for quality tracking
• 🧴 Always provide salt and water—they’re vital for nutrient absorption
• 👀 Observe your horse’s condition and adjust feeding seasonally

11. Ask a Vet for Custom Ration Guidance 🩺

Need help designing a personalized feeding plan? Reach out to Dr Duncan Houston or your local equine veterinarian. For tailored nutrition support, download the Ask A Vet app—where expert advice meets modern horse care. 📲🐴

— Dr Duncan Houston, BVSc