For dairy producers, forage is not just feed — it is the engine of milk production.
Corn silage, haylage and dry hay make up the majority of dry matter intake in most dairy rations. When forage quality shifts, milk production, components and feed efficiency shift with it.
Yet too often, forage quality is estimated by appearance instead of analysis.
In a high-performance dairy herd, that guesswork can be expensive.
Intake Drives Production
Milk production begins with intake. Intake depends heavily on fibre levels and digestibility.
When neutral detergent fibre (NDF) climbs too high, cows eat less. When digestibility drops, energy availability falls. The result is often:
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Lower milk yield
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Reduced butterfat
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Inconsistent components
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Increased reliance on purchased grain
A forage test measures crude protein (CP), NDF, acid detergent fibre (ADF), total digestible nutrients (TDN) and other key values. These numbers allow nutritionists to balance rations accurately instead of compensating blindly with added concentrate.
Even small errors in forage estimates can cost kilograms of milk per cow per day.
Every Lot Is Different
No two silage piles are identical.
Harvest timing, hybrid selection, rainfall, maturity stage, packing density and storage conditions all affect quality. Corn silage cut a few days later than ideal can show higher starch but lower fibre digestibility. Alfalfa harvested at early bloom will test very differently than at mid-bloom.
Sampling by lot — forage from the same field harvested and stored together — gives a clearer inventory picture. Testing at harvest helps with planning. Testing at feed-out confirms dry matter and fermentation stability.
Dry matter shifts alone can significantly alter ration balance.
If milk production changes unexpectedly, forage quality should be one of the first areas checked.
Understanding What Matters in Dairy
While many values appear on a forage report, several have direct impact in dairy systems:
Crude Protein (CP)
Supports microbial protein production and milk yield.
Neutral Detergent Fibre (NDF)
Influences intake. Higher NDF generally reduces consumption.
NDF Digestibility (NDFd)
Critical in dairy. Higher digestibility improves energy extraction and supports higher milk production.
Acid Detergent Fibre (ADF)
Closely tied to overall digestibility.
Total Digestible Nutrients (TDN)
An estimate of energy density.
Relative Feed Quality (RFQ)
Often more useful than Relative Feed Value (RFV) for mixed or grass-heavy forages because it accounts for digestible fibre.
In a dairy ration, small improvements in fibre digestibility can translate directly into improved feed efficiency and margin over feed cost.
Reducing Feed Waste and Over-Supplementation
Without accurate forage data, producers often over-supplement protein or energy “just in case.” That approach increases purchased feed costs and may not correct the real imbalance.
Accurate testing allows:
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Strategic allocation of high-quality forage to fresh and high-producing groups
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Lower-cost forage use in dry cow or late-lactation pens
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Better starch and fibre balancing
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More consistent milk components
Precision feeding starts with precise forage numbers.
Protecting Margin Over Feed Cost
Feed remains the largest operating expense on most dairy farms.
A forage test costs very little compared to the value of the feed it represents. When a silage pile feeds 100 cows for months, even minor formulation errors can add up quickly.
Testing forage quality is not just about nutrition — it is about protecting profitability.
For dairy producers focused on performance, reproduction and efficiency, forage testing should be routine practice.
Because when forage quality is measured accurately, everything else in the ration works better.
