Library · Livestock & pasture
Forage Quality Calculator.
Forage Quality Calculator
Read your hay or silage analysis. RFV, RFQ, TDN, milk-per-ton — and which animals can use this forage.
What each metric means
| Metric | Meaning | Lower is |
|---|---|---|
| Crude Protein (CP) | Total nitrogen × 6.25; protein content | Lower CP = less protein; supplement may be needed |
| ADF | Acid Detergent Fiber. Lignin + cellulose; the indigestible part | Lower ADF = more digestible energy (TDN) |
| NDF | Neutral Detergent Fiber. All cell wall (cellulose + hemicellulose + lignin) | Lower NDF = animal eats MORE per day; better gain |
| RFV (Relative Feed Value) | Comparative quality vs. full-bloom alfalfa baseline (RFV=100) | Higher RFV = better forage |
| RFQ (Relative Forage Quality) | Improved RFV; accounts for fiber digestibility (NDFD) | Higher RFQ = better; better predictor for ruminants |
| TDN (Total Digestible Nutrients) | % of forage that's actually digested | Higher TDN = more energy |
| NEL / NEm / NEg | Net energy for lactation / maintenance / gain | Higher = better |
Hay grade reference
| Grade | RFV | CP % | ADF % | NDF % | Use |
|---|---|---|---|---|---|
| Prime / Premium | ≥ 151 | ≥ 19 | < 31 | < 40 | Lactating dairy; high-performance horses |
| Grade 1 (Premium) | 125-150 | 17-19 | 31-35 | 40-46 | Late-lactation dairy; growing beef; performance horse |
| Grade 2 (Good) | 103-124 | 14-16 | 36-40 | 47-53 | Beef cow + calf; mid-pregnancy ewes; maintenance horse |
| Grade 3 (Fair) | 87-102 | 11-13 | 41-42 | 54-60 | Beef cow maintenance only |
| Grade 4 (Poor) | 75-86 | 8-10 | 43-45 | 61-65 | Limited use — supplementation needed |
| Reject (Utility) | < 75 | < 8 | > 45 | > 65 | Bedding only or compost |
Animal class requirements
| Animal class | Min CP % | Min TDN % |
|---|---|---|
| Dry beef cow (mid-pregnancy) | 7-8% | 52% |
| Beef cow (last 90 days pregnancy) | 9-10% | 56% |
| Lactating beef cow + calf | 11-12% | 62% |
| Growing beef calf (1-2 lb/day gain) | 12% | 65% |
| Lactating dairy cow (high) | 17-19% | 70%+ |
| Maintenance horse | 8% | 55% |
| Working horse / lactating mare | 12-14% | 65% |
| Mature ewe / doe (maintenance) | 9% | 55% |
| Lactating ewe (twins) | 14% | 65% |
| Growing lamb / kid (1/3 lb/day) | 14% | 65% |
Free under CC BY 4.0. Cite as "OAT Forage Quality Calculator (openagriculturetechnology.com)". Quality formulas from NRC, AFGC, and university extension publications.