Forage quality begins in the field and ends with maximum animal performance. It's based on the combined effects of plant and animal management, said University of California (UC) Cooperative Extension farm advisor Shannon Mueller, Fresno County.
What determines forage quality, and how can it be improved in the field? Both questions were answered by Mueller and Dan Putnam, UC statewide alfalfa and forage extension specialist, Davis, CA, at a Hay & Forage Grower- and Mycogen-sponsored forage seminar at the 2010 World Ag Expo in February.
“Some people focus on the chemical analysis (of a forage), especially the total digestible nutrient content (TDN),” Mueller said. “To others, it’s the appearance of the hay; they want weed-free hay with a good green color. Others just want to know how the forage milks.”
Forage quality is a combination of all three qualities, said Mueller, who recommended visual and lab analyses to judge the quality.
A standard laboratory chemical analysis reveals dry matter, crude protein, plus acid and neutral detergent fiber data. Additional analyses can include in-vitro tests, and determining rumen undegradable protein, starch, lignin and mineral levels. The information reveals the relative feed value, TDN, relative forage quality, net energy of lactation, metabolizable energy and other calculated values.
By visually examining forage, growers can see its maturity level at harvest and how weedy it may be.
“Ultimately, we are looking at animal performance,” Mueller said. “The underlying issue is how the animal responds to forage in overall milk, meat and wool production, plus the animal’s overall health.”
Animals can lose interest in feed that’s coarse, has hard stems or other poor texture traits; as well as smelly and overheated forage. Hay intake also depends on just how digestible the forage is, Mueller said. “If the forage fills the animal’s rumen but fails to pass through it quickly, it’s similar to a Thanksgiving dinner where you can’t eat another bite. You’ve actually limited the potential animal performance because they do not continue to eat.”
Growers can improve forage quality in the field to maximize animal performance, said Putnam. Excellent weed control and good harvesting skills help produce high-quality hay with a high leaf-to-stem ratio.
The leaf is where the majority of plant protein and energy are located, he said. Leaf yields level off after 15-20 days in the growth cycle while stem weight continues to increase. Stems are high in fiber but low in protein, and increase in indigestible lignin as the plant gets older. That’s why cutting schedules are so important in influencing alfalfa quality.
Alfalfa hay harvested in spring and fall tends to have less fiber and higher TDN levels than hay cut in summer. Cool-temperature growing regions, including the intermountain areas, tend to produce higher total energy values but slightly less protein. Higher temperatures hasten crop maturity and increase plant respiration. And late afternoon harvests can result in slightly higher TDN values than morning harvests.
Rain damage can cause a 10-20% loss of dry matter and quality, Putnam said. A field study in Wisconsin showed up to a 50% dry matter loss under heavy rainfall conditions.
How well hay is conditioned and harvested affects its quality. Because leaves dry down faster than stems and can fall off or shatter during harvest, fast drydowns are usually beneficial.
There’s little evidence that fertilizers significantly improve forage quality, said Putnam, but “most fertilizers increase alfalfa yield when an element is limited in the soil.”
Pests and diseases can reduce leaf percentage and quality. Alfalfa weevils and leafhoppers can be two of the worst culprits.
Most weeds in hay, especially grasses, can lower forage quality and reduce consumption. So weed control is crucial. “Animals have been killed by weedy alfalfa fields,” Putnam said. “Some weeds are very toxic, including fiddleneck and groundsel, which contain poisons for animals. Others, such as foxtail, can irritate animal mouthparts. Weeds are also a perception problem; hay customers don’t like to see weeds in the hay.”
Choose alfalfa varieties carefully, he advised. “Yield is probably the most important factor for variety selection followed by disease resistance and persistence, and then quality potential. I would choose varieties primarily on the yield potential and then look at quality factors as a secondary consideration.”
To evaluate your forage’s quality, Putnam recommends a single hay test. He suggested the following steps to take forage samples that accurately represent a load or stack of hay:
• Use a very sharp coring device with a 3/8-¾” diameter to cut through the hay.
• Insert the device into the butt ends of bales between the ties, not the sides.
• Gather random samples. Every fourth or fifth bale is fine, but sample the entire stack.
• Get a least 20 cores; composite them together.
• Gather a half-pound sample.
• Don’t leave samples on the truck dash in the hot sun.
• Only use a certified lab.
• Ask the lab to grind the entire sample.