Manitoba Green Gold Program:
Optimizing Forage Harvest Timing
Harvesting high-quality forage in Manitoba has traditionally relied on visual indicators such as late bud or first bloom. However, these stages can be delayed by climatic conditions and are not always reliable. To improve accuracy, the Green Gold Program was established to determine the ideal timing for the first alfalfa cut.
Key Findings
  • Historical data shows most alfalfa fields reach the optimum 150 RFV (Relative Feed Value) at early to mid-bud stage, not at late bud or first bloom.
  • RFV declines by an average of 5 points per day, with the fastest drop occurring early in spring.
  • To achieve 150 RFV in the yard, cut alfalfa at 170 RFV, as quality typically decreases by 20 points between cutting and delivery.
Evaluation Methods
  1. NIR Analysis
    Scissors-clipped samples analyzed using Near Infrared Spectroscopy at commercial labs.
  2. PEAQ Method
    The Predictive Equation for Alfalfa Quality, developed by USDA, estimates RFV of standing crops.
    • Applicable only for the first harvest.
    • Subsequent harvests generally reach optimum stage within 500 Growing Degree Days.
Harvest Timing Insights
  • Historical data shows the optimum harvest window (170 RFV) spans about three weeks (May 31–June 13), averaging June 7.
  • Timing varies annually as well as region to region - do not rely on calendar dates. Regular monitoring is essential. Generally harverst is later in the western and northern regions of the province.
  • For annual data results please refer to the Manitoba Forage and Grassland Association website.
Using Green Gold Information in Deciding When to Cut
Please note that there are several adjustments that need to be made in order to cut based on Green Gold information:
  • Expect about 15 to 20 points RFV loss between the standing crop and the harvested crop, due to leaf loss and continued respiration.
  • If the sample turn-around time is one day, the hay will be five points lower than when cut.
  • The percentage of grass in the stand will also lower the RFV of the hay.
  • Alfalfa grown on lighter soils is usually more advanced that alfalfa grown on clay soils.
  • Unless you have the capacity to harvest all your hay in one day, start your harvest early to produce the highest quality forage.
 
Using Relative Feed Value (RFV) to Rate Forage Quality
Relative Feed Value (RFV) has become a widely accepted industry standard for expressing forage quality. RFV is calculated from laboratory analysis of two fibre components:
  • Acid Detergent Fibre (ADF): Represents the indigestible portion.
  • Neutral Detergent Fibre (NDF): Represents the digestible portion and indicates potential daily dry matter intake.
RFV provides a reliable basis for comparing feed value across different forages. Many livestock producers use RFV to allocate feed according to the nutritional needs of various livestock groups.
 
Impact of Grasses on RFV
Grasses generally contain higher fibre than alfalfa, causing them to reach 150 RFV more quickly. To achieve similar forage quality in an alfalfa-grass mixture compared to pure alfalfa, harvest should begin one week earlier.
 Fibre Composition: Alfalfa vs. orchardgrass
 
Relative Forage Quality (RFQ)
While Relative Feed Value (RFV) is widely used, it does not account for differences in digestibility among forage species. For example, soft grasses such as Orchard Grass often have higher digestibility than RFV suggests, leading to undervaluation.
To address this, the Relative Forage Quality (RFQ) test was developed at the USDA Dairy Research Facility in Wisconsin. RFQ improves upon RFV by measuring:
  • Fibre content in the plant, and
  • Actual digestibility, determined using rumen fluid in laboratory analysis.
This provides a more accurate estimate of forage quality and animal performance potential, especially for mixed or grass-heavy forages.
 
The Drying Process
Knowing when the field is ready to harvest is only part of producing high-quality hay. Weather conditions, particularly untimely rains, can significantly impact forage quality. Understanding the drying process is essential for making effective management decisions.
Moisture Testing Tools:
  • Electronic moisture testers or the microwave test are valuable for determining forage moisture levels.
  • For detailed instructions, contact Manitoba Agriculture.
 
Tips for Producing High-Quality Hay
  • Cut early in the morning to maximize drying time in one day. Aim to reduce moisture below 50% quickly to minimize transpiration losses.
  • Cut only what can be baled in one day to avoid quality loss.
  • Increase drying rate by laying forage in a wide swath, drying below 50% moisture, then turning.
  • Avoid aggressive handling for legume hays (alfalfa):
    • Raking, tedding, or double conditioning works better for grass hays.
  • Use a swath turner early in the morning before baling to gently flip the swath for even drying.
  • Reduce leaf loss by:
    • Turning or raking only when forage moisture is ≥40%.
    • Raking alfalfa when relative humidity is ~50% (e.g., early-morning dew).
  • Swath considerations:
    • Wide, flat swaths dry faster but are more prone to bleaching and rain damage.
    • Narrow swaths are easier to flip and allow better airflow.
  • Cut high enough to avoid soil contamination (e.g., gopher or mole hills).
  • Use multiple balers for uniform hay quality and reduced leaf loss.
  • Monitor bale moisture hourly:
    • Safe baling moisture: ≤18% (preferably 15%).
    • Export requirements: ≤12% moisture.
  • Store hay under cover immediately:
    • Hay sheds are most economical long-term; tarps are an alternative.