The art, science and skill of forage management

CM-MR-3-The art, science 3by Sally Colby
A dairy farm that’s milking 1,550 cows in a four times a day system while maintaining a 30,000 pound herd average and a SCC of 150,000 is doing a lot of things right, starting with forage management.
That’s the case at Mercer Vu Farms, Inc., in Mercersburg, PA, where the Hissong family recently hosted a Professional Dairy Managers of Pennsylvania (PDMP) issues forum. One topic of interest for many who attended was forage management. Troy Brown, national forage consultant for Cargill, addressed silage harvest and bunker management.
“Harvesting at the correct moisture level is critical, whether it’s corn silage or haylage,” said Brown. “Then we need the right additive for each situation, whether it’s a bag, baleage, a traditional upright silo, a bunker or a drive-over pile.”
Brown emphasizes that there is no perfect storage facility. “Each storage facility has strengths and weaknesses,” he said. “There may be a perfect one for your management style or your farm situation, but there isn’t a perfect one that has perfect forage every single time.”
The role of proper bunker packing can’t be overemphasized. “Packing is one of the highest returns on investment you can make when it comes to forage in a bunker or a drive-through,” said Brown. “Air is the enemy. Any time you can control air when you’re dealing with forage, you win. Mold and yeast are aerobic organisms and they cannot go without air. The tighter we can pack, the less air can penetrate.”
The goal of packing is to increase dry matter density. “We’re trying to decrease porosity — the measure of air space between particles,” said Brown, noting that air can travel as deep as three feet into the face of a bunk. “There’s enough air for mold and yeast to get started. If we can reduce air penetration 18 inches to 24 inches, that’s much less of a head start (for mold and yeast). Most people don’t worry about aerobic stability until the feed is in front of the cows, but that isn’t when aerobic stability problems happen. They happen out on the face, so if that isn’t managed properly, we’re already dealing with issues.” Brown says producers should strive to never have loose feed at the end of the day — everything that is faced and brought down should be fed that day. “Leftover, loose silage can heat up significantly in a very short time, even in winter,” he said. “You want a smooth face and no jagged edges where air can penetrate.”
When it comes to covering a bunker, Brown says he’s an advocate of the two-layer system that includes a thin plastic sheet with lower oxygen permeability than traditional poly covers. A second plastic layer or tarp is placed on top of the thin sheet, and weighting materials (tires, sandbags) are placed on top to hold the layers in place. A similar one-step cover incorporates a non-permeable layer into the plastic, but Brown says that producers who have tried both almost always return to the two-step system. “The reason for that is that the first layer is 1.5 ml plastic,” he said. “It’s much more flexible, not nearly as rigid. During the early phases of fermentation, if we apply the cover properly, it ‘sucks’ down during the heating phase and seals on top of the forage. The 5 ml is too rigid. If you’re going to keep that in contact with the forage, you have to have it weighted down. The 1.5 ml layer underneath improves that.”
To ensure ample feed for both the milking herd and 1800 replacement heifers, the Hissongs grow 1,950 acres of corn on 15 inch rows with an average plant population of 32,000 to 34,000. The Hissongs have ordered a 40 ft. wide planter and will be planting 20 inch rows next year, mainly because the crop enterprise has grown and corn plantings will likely yield more corn for shelling. All crops, including grains, are no-tilled. The Hissongs use minimum surface tillage when needed to break up crusting or when a field has experienced heavy traffic.
In addition to corn, the Hissongs grow 600 acres of alfalfa, yielding four to five cuttings each season. Although the farm has its own packing tractors and trucks for hauling, the Hissongs use the services of a custom operator for mowing, merging and chopping. Because filled trucks are weighed coming in from the field, Hissong knows that he consistently gets 4,500 to 4,700 tons of corn silage in one particular bunk.
The Hissongs have added precision planting tools and found that the benefits outweighed the costs almost immediately when an entire pallet of seed was unused. With the help of Google maps, fields are identified and planters are programmed to seed at the optimum rate for each field.

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