– Mark Sulc, OSU Extension Forage Specialist
The warm temperatures this spring have stimulated growth of hay crops in Ohio and they are well ahead of normal development for early May. The only exception is where spring freezes significantly damaged the crop a few weeks ago. But for most stands, timing for first harvest of high quality forage is coming earlier than normal. Below are the optimal neutral detergent fiber (NDF) targets for high quality forages:
Forage NDF for high producing and early lactation dairy cows
Legumes: <44 (<42% is ideal)
Grasses: < 53% (50% is ideal)
Mostly legume mix: 42 to 45%
50/50 Mix: 44 to 48%
Mostly grass mix: 46 to 49%
Pure grass stands should be harvested in the late boot stage just before the heads start to peek out. If any heads can be seen, the NDF is probably 55%, past the optimal for dairy cows.
The neutral detergent fiber (NDF) content of pure alfalfa stands can be estimated quickly and easily based on the stage of the most mature stems and length of the tallest stems. Last week the alfalfa in central Ohio was near 32% NDF already. This method is explained in detail in the factsheet “Estimating Alfalfa Fiber Content in the Field” located on the new forages website (https://forages.osu.edu/forage-management/harvest-storage).
A timely first and second cutting is critical for high quality forage. Fiber accumulates faster in the first two growth cycles in May and June than it does later in the summer. So for high quality forage, take your first and second harvest early if at all possible.
Later in the summer (July into August) you can extend the cutting interval because the quality decline with delayed cutting is much less then than it is this time of the year.
An exception to the above rule of timely first cutting is for forage stands that suffered significant injury this winter or from spring frosts. Those stands should be allowed to recover longer this spring and get into the bloom stage to build up energy reserves. Use that forage for animals having lower nutrient requirements.
If high quality is not such a concern, a later first harvest will provide more yield. For beef cows or other animals with lower nutrient requirements, you can harvest forage in the heading (grass) or flower (legumes) stages for adequate quality. But don’t get too comfortable waiting. Watch for harvesting weather windows, because forage quality changes fast this time of year.