As our nation was first settled, the native species in vast areas of the U.S. were grasses. In some areas, including the traditional Midwestern Corn Belt, as the acreage devoted to grain farming increased the acreage of grasses decreased (This is continuing to occur, much to the sorrow of upland bird hunters: The pheasant population in that region has declined considerably in the past five years or so due to loss of habitat as farmers have planted row crops “fencerow to fencerow.”). But even where the soils and climate were better suited for dairy farming, farmers started planting alfalfa—usually straight alfalfa, not alfalfa-grass—and grasses were often looked upon as weeds that should be eliminated.
Is grass a weed? Not in the Northeast! In general, conditions (internal soil drainage, topography, pH, severe winters) in much of the Northeast U.S., particularly northern New York and much of New England, are such that either alfalfa-grass or straight grass yields better than straight alfalfa. Therefore, there has never been the desire by dairy farmers to eliminate cool-season forage grasses from their crop rotation. Even native grasses, including sweet vernal, meadow foxtail and quackgrass, find a place in permanent pastures. This is proving to be an advantage, because grasses are a good fit with the increased use of corn silage on dairy farms, particularly (but not exclusively) on larger dairies.
Corn is king and alfalfa is queen of forage crops, but …
There are at least three reasons for the increased use of corn silage on dairy farms. First is yield: An acre of corn silage will almost always yield more tons of dry matter than any other forage crop. As dairy farms expanded, they were often limited by the availability of cropland to grow the increased amount of feed needed by the herd. Therefore, the acreage mix on many of these farms changed from mostly hay crops to an increasing reliance on corn harvested for silage.
The second reason is ease of mechanization: Even if the hay crops are harvested for silage, it takes a lot more labor and time to harvest three or four cuts of hay crop than a single harvest of corn silage.
Third is the matter of weather risk: Hay crops must be windrowed and wilted to the correct dry matter content, a process that takes at least a day and sometimes two, particularly with the first (and highest yielding) crop. Delaying harvest to avoid inclement weather can result in lost quality, since hay crops decline in quality very quickly after the ideal harvest stage.
Corn silage, on the other hand, has a much longer “harvest window.” A few days of rainy weather when the crop is ready to harvest may be a problem, but it’s seldom a disaster, since corn silage can be successfully harvested and ensiled at a fairly wide range of whole plant dry matter (DM) contents. Although my preference is 33 to 35 percent DM, I’ve seen good quality corn silage at 30 percent DM and also at 40 percent DM. Since corn silage usually dries down at about 0.5 to 0.75 of a percent per day, 10 units of DM can represent about two weeks in the harvest window.
Dairy farmers’ increased reliance on corn silage has generally been successful, but it’s not without problems. Corn silage has a relatively high nonfibrous carbohydrate (NFC) content, averaging about 30 percent NFC. High NFC has been implicated in the increased lameness in dairy cows. Alfalfa is lower in NFC—near 25 percent—while cool-season forage grasses, including timothy, orchardgrass and tall fescue, have NFC levels of about 15 percent. Therefore, the more corn silage included in the ration, the better grass looks in comprising the hay crop portion of the ration.
It’s been estimated that 20 to 25 percent of milking cows in the Midwest are mildly to seriously lame, resulting in higher vet bills and lower milk production. More than half of these cases of lameness are due to disease or injury, but more than 40 percent of these cases are nutritionally related: too much grain and/or not enough fiber. Why does lameness appear to be more of a problem in the Midwest than in the Northeast? Maybe it’s because our farmers never stopped feeding grass or alfalfa-grass.
Balancing the “big three” forages
While dairy farmers feed a wide range of forages, including winter and spring small grains, soybeans, sudangrass and sorghum-sudan, I consider the “big three” forages to be whole plant corn silage, alfalfa and grass. While I often focus on grass this doesn’t mean that I’m down on alfalfa—far from it. Alfalfa is truly the Queen of Forages, and nothing will produce forage with the protein content that alfalfa does. But too much of a good thing isn’t profitable, and we need a balance of forage species to maximize milk production and animal health.
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