Making sure forage quality is up to par
Great effort is put into creating high quality forages. Seed selection, harvesting and storage techniques, cultural practices, harvesting in a timely fashion are all required. Such forages are the foundation of high milk production, good animal health from fewer concentrates fed and more economical rations relying less on purchased feed.
High quality forage may come from a wide range of crops: alfalfa, corn silage, perennial grasses, cereal grains and other annual forages. Likewise, poor quality can be found in all these crops as well.
Despite our best efforts and ever-increasing knowledge of what makes a high quality forage, nature intervenes or sometimes we just make mistakes so that forage quality is not up to par.
Updating our idea of quality forage
First, the feed should be well preserved, for hay or fermented feeds, harvested at the correct moisture to be free of excessive molds, yeasts and decay. It should be under a roof, wrapped, bagged or sealed in a bunker or tower silo soon after harvest. The method of ensiling should provide for a dense, well packed feed. Inoculants are helpful for fermented feeds.
For silages the length of cut and processing should provide for good packing and provide effective fiber and well processed grain for optimal utilization. It should be managed at feed out to maintain that quality with proper sizing of the feeding face and tools such as a facer to not disrupt the feeding surface too aggressively. That is a long list, but all are prerequisites before we address feed tests, analytical tools and ration formulation.
Our understanding of high-quality forage has evolved. Before we had good tests for fiber and energy content protein was equated with quality, as younger, more immature, more highly digestible forages also tend to be higher in protein which also benefits in lower supplementation needs.
The protein was a great plus but as we have come to understand, the intake potential and the energy, intake potential and digestibility of the feed is more relevant to success. We moved on to looking for lower fiber feeds and we are still largely there today.
Fiber digestibility tops fiber level
How can a high fiber feed, fiber being lower in energy than protein, starch, sugars and soluble carbohydrates be a valuable feed? The answer is because cows REQUIRE fiber. They need it for rumen function and health, so if a forage is high in fiber, it meets the cows needs more easily.
The problem and frequent confusion is that as a plant matures, and fiber increases in general the digestibility of the fiber decreases, and at some point, we no longer consider it feed, we use terms like straw or stover to describe the product. Not all feeds that are high in fiber are low in digestibility.
There are forages that defy the rule, are we missing their potential value? Oats planted late in the season for fall harvest, triticale, all cereals, harvested at late vegetative stages, warm season annuals with the BMR trait are examples.
We now find that these grasses can have the highest fiber digestibility of all forages. These feeds tend to be lower in protein and starch so higher in fiber. The sum of the parts: protein, fiber, soluble carbohydrates, fat, mineral (ash) must add up to 100%.
There are advantages for working with these forages. For example, feeding corn silage high in NDFd may have an end point when too much grain enters the diet, or for alfalfa, when too much of one type of protein enters the diet.
Matt Lippert is the dairy educator for Division of UW Madison Division of Extension Clark and Wood Counties