To optimize something is to make the best or most effective use of it. Rather than maximizing one aspect of a resource or minimizing its worst part at the expense of all others, optimization finds the sweet spot on the spectrum of all of its attributes.
In last week’s Field Crops Virtual Breakfast webinar from Michigan State University Extension, Kim Cassida explained how to optimize forage quality in hay and haylage. To begin her presentation, she explained the difference between forage quality and forage nutritive value.
Forage quality is defined as the potential of a forage to produce a desired response in an animal, whereas forage nutritive value describes the specific quantifications of nutrient concentrations, digestibility, and the end products of digestion. With that said, forage nutritive value is just one factor of forage quality.
Another factor is palatability. Cassida, a forage and cover crops specialist, suggested forage can grow well and yield high, but if livestock don’t like to eat it, it shouldn’t be considered a quality feedstuff. She added that forage must be free of plant anti-quality factors like nitrates, toxins, and dust. Anti-quality factors that originate from the growing environment include mold, ash, weeds, and manure.
Cut it on time
Harvest timing also influences forage quality, although often at the expense of yield. “This is a classic dilemma in forages because as yield goes up, quality goes down,” Cassida said.
She asserted that harvesting at a younger stage of plant maturity is the single-most significant way to improve forage quality. As forage matures, plant cell walls thicken and accumulate lignin to support growth. Thicker cell walls ultimately reduce the proportion of cell contents — protein, sugars, and starch — and more growth results in lower leaf-to-stem ratios.
According to a Wisconsin study, first-cut alfalfa relative feed value (RFV) declined 2.7 to 7.5 points per day, depending on farm location, field conditions, and weather. Cassida noted that forage quality changes typically occur faster during first cutting than in alfalfa regrowth. Nonetheless, she emphasized the drastic reduction in quality that can occur from one day to the next. Moreover, she stated forage quality will never be better than it is the moment it is cut, emphasizing the need for a swift transition from the field to storage.
Postharvest quality losses can occur from plant respiration and rain damage during dry down; leaf shatter and soil contamination during conditioning, tedding, or raking; and failure to store forage properly. Although chopping haylage can help avoid some of these quality losses, laying a wide swath will help facilitate rapid dry down when making hay.
“Laying a wide swath will speed up phase-one drying because you’re exposing a lot of the material to the sun to drive that photosynthetic drying,” Cassida said. Current recommendations state swath width should be at least 60% to 70% of mower width. Research shows this can reduce forage moisture to levels suitable for baling more than 24 hours sooner than laying a narrow swath.
Price hay the right way
Considering the key indicators on a forage test, Cassida suggested crude protein (CP), neutral detergent fiber (NDF), ash, and total digestible nutrients (TDN) are the primary measurements to focus on when feeding hay and haylage. If selling hay, it will pay to be privy to the RFV and/or relative forage quality (RFQ) on a forage test.
These index values are tools for pricing and marketing hay. RFV only accounts for NDF and acid detergent fiber (ADF), whereas RFQ additionally factors in protein, fats, and fiber digestibility.
“This is a huge factor because one thing we learned early on was that RVF didn’t predict the feed value of grasses very well. The reason for this is because the fiber digestibility for grass is a lot greater than it is for alfalfa,” Cassida said. “When we try to use RFV on grasses or alfalfa-grass mixtures, it’s going to underestimate their quality.”
To demonstrate this, she referenced a study that compared average RFV and RFQ values of alfalfa and grass samples. The average values of both indexes were virtually the same for the alfalfa samples, whereas grass RFQ was significantly higher than RFV of the same sample. For example, grass with 150 RFQ registered as 110 RFV.
“This is important because when we look at pricing hay on the market, we are going to see a premium of about $2 per ton for every extra point of RFV or RFQ in a forage test,” Cassida said. “If you were valuing your grass hay on the RFV value, it would feed out similar to the number shown for RFQ, but you would not be charging enough for it.”
Know your nutrient needs
Whether feeding forage in-house or selling it off-farm, knowing the need of the end-consumer will aid in optimizing its quality.
“You have to keep in mind that the nutrient concentration and the availability of nutrients that is appropriate for your intended purpose is going to be different depending on what that purpose is,” Cassida said. “We don’t have the same quality parameters for every type of animal.”
She explained the hierarchy of livestock nutrients needs, starting with maintenance animals, which would have the lowest energy demands. Working animals, such as riding horses, were next, followed by pregnant livestock, growing young stock, and lactating animals having the greatest nutrient needs.
Cassida suggested hay with 150 RFV should be the benchmark for good-quality hay that will meet the needs of most nonlactating animals. For lactating cows — and growing heifers — a benchmark of 170 RFV is more desirable. Moreover, she provided the following parameters for what she considers dairy-quality hay.
• Less than 10% ash
• At least 20% crude protein
• Less than 40% NDF
• At least 60% TDN
Cassida added that one benchmark specific to horse hay is that most owners are looking for forage that is less than 10% WSC. “Horses can’t tolerate more sugar in the diet, so there is a premium market for that product,” she said.
