by Sally Colby
Dairy farmers know that forage is the basis for a good dairy ration, but 2017 has been a challenging year for forage production.
Joe Lawrence, forage specialist for PRO-DAIRY, said precipitation from April through the end of July has been 50 percent or greater, and growing degree days (GDD) in six locations throughout New York are behind normal. In almost all locations, over half the deficit in GGD occurred in May. “One of the consequences of the wet spring we had is that we had a lot of late-planted crops,” said Lawrence. “We lost growing degree days in May. But if the crop was still in the bag and not in the ground, it really isn’t as consequential as you might think.”
Lawrence noted weather records from June through July indicated we weren’t too far behind in GGD, and that lack of sunlight and saturated soils have been the most limiting factors in timely harvest of quality forage.
“We’ve had to deal with a lot of wet fields, the late harvest of forage crops,” said Lawrence. “The potato leafhopper has been a significant issue throughout New York this summer and has forced folks to change their harvest patterns, and we’ve had some lost yield and quality. One of the biggest things we need to do now is recognize what we have in inventory; what we’re dealing with.”
Lawrence said at this point, producers should have obtained forage samples from cuttings already in and know the quantities of those forages. “When we’re dealing with such a wide spectrum of forage quality in this challenging year,” he said, “being able to identify the forages you have, quantify what’s there and what classes of animals you’ll feed them to is going to be critical.”
Although dairy farmers may have good hay inventory at this point, there’s still a desire to maximize quality and obtain as much feed for lactating cows as possible. Lawrence said one consideration for late-season harvest, especially of alfalfa, is risk of winter injury. However, some farmers may be willing to risk some degree of winter kill in order to obtain sufficient tonnage. Lawrence referenced growing degree day models developed by Jerry Cherney of Cornell University that indicate where the biggest risks are with late-season alfalfa harvest. “That risk tends to be around early September,” said Lawrence, “because you don’t accumulate enough growing degree days after the cutting for the regrowth to prepare for winter. So the time from late August to mid-September is probably the most dangerous time to be cutting an alfalfa crop. You’ll get enough regrowth that you’ll deplete the root system, but you’re likely to get frost before the regrowth is able to capture sunlight and replenish the reserves for the winter.”
Cutting height is an important management tool for late-season hay crops. “You’ll pick up yield by lowering cutting height,” said Lawrence. “But the reverse is that you’ll pick up higher fiber in the lower stem. For alfalfa, there isn’t concern for plant injury other than in fall when you might want to leave it taller.”
Lawrence noted when grasses are cut too low, potential regrowth is stunted and stand damage may result. He suggests leaving at least three to four inches after the last cutting. Cutting height can also impact drying time, especially with wet soils and short drying windows.
The popular ‘haylage in a day’ concept minimizes the time between cutting and ensiling to preserve as much sugars in the plant as possible. “You want to minimize respiration losses,” said Lawrence. “If you have a tight, narrow window, the top dries out and underneath there’s a lot of respiration loss.” Lawrence noted this isn’t new information, but critical in a year when farmers are forced to work in narrow weather windows.
Lawrence outlined the four ways hay loses quality when it’s rained on: leaching of soluble carbohydrates, vitamins and minerals; increased and prolonged plant respiration; leaf shattering; and microbial breakdown of plant tissue. “Another place we can help maximize quality is by paying attention to leaf loss in alfalfa,” he said. “There’s a strong correlation between the feed value and percent of leaves remaining on the plant. Think about how you’re raking, make sure rakes are set up properly and again, minimize the time from cutting to ensiling to retain leaves on the crop for the quality we need for feed going into this winter.”
Ron Kuck, dairy specialist for Jefferson County, said forage testing helps estimate the quality of forages and includes analysis of protein, fiber, NDF, digestibility, fermentation profile and ash content.
“It gives you a great idea of where to allocate forages to the proper group of dairy animals,” said Kuck, explaining the benefits of forage testing. “Lactating herd, late lactation cows, dry cows, young heifers and bred heifers.” But a forage analysis is only as good as the sample submitted. “As forage is coming in, it’s a good idea to have a grab bag sample for every load that comes in,” he said. “Mix those together so you get a nice, composite sample. That’ll give you an idea of what you have before it’s fermented and you feed it out. Digestibility changes during fermentation, so hopefully we do a good job of fermenting and it won’t change a lot.”
Kuck said the results of fermented forage sample results help you, the herd nutritionist and veterinarian optimize the feeding program and identify potential issues. “Look at the fermentation profile,” he said. “High butyric acid or high acetic acid forages are more apt to lead to metabolic issues.”
Samples taken properly will yield the most accurate results. Kuck suggests taking multiple subsamples and mixing them for a composite sample rather than selecting what looks best. “You want to sample what’s really going into the cows,” said Kuck. “Right from the machinery that’s grabbing the forage from the face of the bunk right before it goes into the mixer so this is actually what the cows are eating.” Kuck cautioned wet forage presents a potential safety concern if the face is unstable.
Kuck said it will be difficult to predict the likelihood of mycotoxins in silage this year. “Wet weather and injury to living tissue gives us a better chance of having both molds and mycotoxins,” he said. “We’ve had a lot of insect damage in alfalfa with potato leafhopper and western bean cutworm in corn for silage.”
When it comes to storing forages, the key is to minimize respiration losses, which results in loss of carbohydrates and energy. Pack bunks, bags or bales well and use inoculants. “When you feed out, face management and bunk management are very important,” said Kuck. “A stable forage in the bunk will make a stable forage in front of the cows. Maximize carryover and make sure you get the right forage into the right class of animals.”
Feed out management is as important as putting the feed into the bunker — the goal is to minimize the amount of bunker face exposed to oxygen. “Keep it as clean as you can,” said Kuck. “Don’t have a lot of fall-down and waste there, and keep the bunk silo floor as clean as you can. If you have bags or bales on the ground, be careful not to pick up soil and other contaminants.”