1. What is Relative Feed Value (RFV)?

The Relative Feed Value (RFV) is an index used to compare the quality of forages, particularly corn silage. It combines measures of digestibility (DDM) and intake potential (DMI) into a single number that can be used to rank forages.

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 of the forage and how much an animal is likely to consume.

3. Importance of RFV Calculation

Details: RFV helps farmers and nutritionists evaluate forage quality, balance rations, and make decisions about forage purchases and feeding strategies.

4. Using the Calculator

Tips: Enter DDM and DMI as percentages. Both values must be positive numbers. Typical DDM values range from 50-80%, and DMI from 1-4% of body weight.

5. Frequently Asked Questions (FAQ)

Q1: What is a good RFV value for corn silage?
A: RFV values above 150 are considered excellent, 125-150 good, 100-125 fair, and below 100 poor quality.

Q2: How is DDM measured?
A: DDM is typically estimated using laboratory analysis like near-infrared spectroscopy (NIRS) or wet chemistry methods.

Q3: Does RFV account for protein content?
A: No, RFV only considers energy value through digestibility and intake. Protein content should be evaluated separately.

Q4: Can RFV be used for all forages?
A: While primarily used for legumes, it can be adapted for corn silage with appropriate adjustments.

Q5: How often should RFV be tested?
A: Test at harvest and periodically during storage, as quality can change over time.