Forage

What is Forage?

Forage is any plant material harvested for animal feed, including grasses (timothy, bermudagrass, orchardgrass), legumes (alfalfa, clover), cereal crops (corn silage, oat hay), and crop residues (corn stalks, wheat straw). Forage is the foundation of ruminant nutrition — it provides the fiber necessary for healthy rumen function.

Forage quality is measured by several parameters: Neutral Detergent Fiber (NDF — total fiber, inversely related to intake), Acid Detergent Fiber (ADF — indigestible fiber, inversely related to digestibility), Crude Protein (CP — ranges from 8% in straw to 22% in premium alfalfa), and Relative Feed Value (RFI — higher is better, >150 is excellent).

High-quality forage (RFV >150, CP >18%, NDF <40%) maximizes DMI, milk production, and feed efficiency. Low-quality forage (RFV <100, CP <10%, NDF >55%) limits intake and production, requiring concentrate supplementation.

Forage particle size is critical for rumen function. Effective fiber (particles >4 cm) stimulates chewing and rumination. Chopping too fine reduces effective fiber, leading to ruminal acidosis. The ideal TMR particle size distribution follows the Penn State Particle Separator guidelines.

Forage Quality Testing

Test forage at three critical points: at harvest (to assess timing), upon delivery (to verify quality), and before ration formulation (to balance the TMR). Key parameters to measure: NDF (neutral detergent fiber — target <40% for lactating cows, as NDF >50% limits intake), ADF (acid detergent fiber — target <30%, lower means higher digestibility), crude protein (14–22% for lactating rations, with legumes on the higher end), and RFV (relative feed value — >150 is excellent, 120–150 is good, <100 is poor). A full forage analysis costs $25–$50 per sample and should be done at least monthly. Forage variability between cuttings can be 20–30% — testing each delivery or cutting prevents ration imbalances. NIR (near-infrared spectroscopy) labs provide faster turnaround (24–48 hours) vs wet chemistry (5–7 days). Maintain a forage quality log and review trends quarterly with your nutritionist.

Forage Harvesting Best Practices

Chop timing is critical for maximizing quality: grasses should be harvested at the boot stage (before seed head emergence), and alfalfa at 1/3 bloom. Delaying harvest reduces protein and increases fiber — every week of delay can reduce RFV by 10–15 points. Chop length for corn silage should be 1/2–3/4 inch (12–19 mm) for optimal fermentation and rumen function. For grass silage, chop length of 1–2 inches is appropriate. Packing density is crucial for silage preservation — target >15 lbs DM/cubic foot for bunker silos, >18 lbs DM/cu ft for bag silage. Achieve proper packing by spreading thin layers (6–8 inches) and driving over them frequently. A 200-cow herd needs approximately 30–40 lbs DM/cow/day of forage dry matter, so plan harvest timing and quantities to meet annual needs plus 10% shrink allowance.

Forage Storage Methods

Baleage (wrapped round bales) offers flexibility for small herds with 50–150 acres — lower infrastructure cost but higher shrink (10–15%). Dry hay requires good weather for curing but has the lowest storage cost ($10–$20/ton in storage fees). Corn silage in bunker silos provides the most consistent quality and lowest cost per ton ($50–$80/ton) for medium to large herds. Bag silage (silage bags) costs $15–$25/ton but requires less capital investment than bunkers. Tower silos offer the best shrink control (2–5%) but have high upfront costs ($50,000–$150,000). Cover bunker silos with 6-mil polyethylene plastic and weigh down with tires or sandbags — exposed silage can lose 20–30% of dry matter to spoilage. Shrink losses range from 5–20% depending on storage method, face management, and covering practices. Proper face management (remove 6–8 inches per feeding, maintain a smooth face) prevents heating and spoilage.