1. What is Relative Feed Value?

Relative Feed Value (RFV) is an index used to compare the quality of forages for cattle. It combines measures of digestibility (DDM) and intake potential (DMI) into a single value, with higher numbers indicating better quality forage.

2. How Does the Calculator Work?

The calculator uses the RFV equation:

Where:

• \( DDM \) — Digestible dry matter (%)
• \( DMI \) — Dry matter intake (% of body weight)
• 1.29 — Scaling factor to standardize values

Explanation: The equation combines both the digestibility and potential intake of the forage into a single index number.

3. Importance of RFV Calculation

Details: RFV helps farmers and nutritionists compare different forages and balance rations for optimal cattle nutrition and production.

4. Using the Calculator

Tips: Enter DDM and DMI as percentages. Both values must be greater than 0 and typically range between 40-80% for DDM and 1-3% for DMI.

5. Frequently Asked Questions (FAQ)

Q1: What is a good RFV value?
A: Alfalfa hay with RFV >150 is considered premium, 125-150 is good, and <100 is fair to poor quality.

Q2: How is DDM measured?
A: DDM is typically estimated from ADF (acid detergent fiber) content using laboratory analysis.

Q3: How is DMI measured?
A: DMI is estimated from NDF (neutral detergent fiber) content, with lower NDF generally indicating higher intake potential.

Q4: What are limitations of RFV?
A: RFV doesn't account for protein content, mineral levels, or anti-quality factors that may affect forage value.

Q5: Is RFV used for all forages?
A: RFV is most commonly used for legume forages like alfalfa. Other indexes may be better for grasses.