Trial shows benefit in high-forage diets Brown midrib corn silage put more milk in the tank than silage made from four other types of hybrids in a recent Wisconsin study.
"Of the hybrids tested, only the brown midrib stood out, with a small response from the waxy corn," says Larry Satter, a nutritionist at the U.S. Dairy Forage Research Center in Madison.
Satter compared milk production of cows fed a total mixed ration (TMR) that contained silage made from waxy, high-oil, multileaf, brown midrib and conventional grain hybrids. In a sixth treatment, cows were fed brown midrib corn silage, but at a higher proportion of forage in the diet than the other brown midrib treatment.
"Like producers, we wanted to know if these diverse hybrids differ from one another in terms of supporting milk production" says Satter. "The hybrids we tested represented a wide range of corn genetics."
Satter's work is part of a Monsanto Dairy Business-funded multilocation study. Results from the other two states aren't completed yet. Interpretation of results for this study are preliminary until all the data are included, say Monsanto representatives.
The four-week-long Wisconsin study included 144 cows divided into six groups. Five of the groups were fed a TMR consisting of 50% forage and 50% concentrate of high-moisture corn, roasted soybeans, vitamins and minerals. Of the forage portion, 75% was corn silage and the balance was alfalfa haylage.
"That's a high proportion of corn silage and a little more than we would usually recommend dairy producers feed," he notes.
In the sixth treatment, cows were fed a ration of 65% forage and 35% concentrate. The forage portion was 75% brown midrib corn silage, 25% alfalfa haylage.
The lactation results are listed in the table on page 16. On a 3.5% fat-corrected milk basis, the brown midrib corn silage, fed in the 65-35% ration, produced the most milk - 79.2 lbs/cow/day. Next highest was the waxy corn at 76.1 lbs/cow/day.
If dairy producers utilize brown midrib silage, Satter suggests that they feed a little more total forage than when feeding a ration with silage made from conventional grain hybrids. He recommends that rations with conventional corn hybrids be 55% forage and 45% concentrate. If the silage is brown midrib, feed 60-62% total forage and 38-40% concentrate. He points out that brown midrib corn contains less lignin, which is impossible for cattle to digest, and producers need to formulate dairy rations to account for the increased digestibility.
Another key factor to keep in mind: Make sure there's adequate fiber in the ration, says Satter.
"Haylage needs to have adequate chop length. We generally recommend a 31/48" theoretical length of cut, but if growers are doing a good job of harvesting at proper moisture levels and a good job of packing, they can utilize a longer cut - 11/42" at most. Feeding a little dry hay might be helpful, too."
While much of the news about brown midrib corn is good, Satter offers several cautions to growers who are thinking about planting it:
Lower silage yield. "Most people would caution that there's a 10% to 15% yield drag with brown midrib vs. conventional corn. Our experience has been that it's less than that, but we've had very good growing conditions in the years we've raised it."
Lower stress tolerance. "Brown midrib corn doesn't do as well under stressful conditions, such as dry weather. Also, it's more prone to lodging because there's less lignin in the stalks."
Higher seed cost. Brown midrib seed is about double the price of conventional corn hybrids, according to Cargill representatives.
Less flexibility. Unlike conventional hybrids, which can be harvested for grain or silage, brown midrib corn is for silage only.
Satter suggests that dairy farmers calculate the economics of brown midrib corn before deciding whether to try it. On the cost side, figure added feed expenses from the expected silage yield reduction and higher seed costs. Then subtract that total from the actual value of the extra milk expected.
He also points out that other types of silage hybrids may have agronomic advantages that make them worth considering.
Larry Satter says it's vital for top herd health and milk production to put as little stress as possible on transition cows.
That's why brown midrib corn silage works well in transition diets, says Satter, a dairy nutritionist at the U.S. Dairy Forage Research Center, Madison, WI.
"It's best for rumen health to feed a diet that's high in forage during the transition period. With brown midrib silage, producers can increase the forage portion of the ration because of the forage's high digestibility," says Satter.
He recently conducted a feeding trial comparing brown midrib and conventional corn silage for transition cows. Three weeks before calving, cows were switched to a transition diet containing 65% forage and 35% concentrate. Two-thirds of the cows were fed conventional corn silage and alfalfa haylage; the other third ate brown midrib silage and alfalfa haylage.
After calving, the 112 cows were divided into three groups and fed one of the following diets:
1) 55% forage, 45% concentrate. The forage portion was 58% conventional corn silage and 42% alfalfa haylage.
2) 65% forage, 35% concentrate. The forage portion was 58% conventional corn silage, 42% alfalfa haylage.
3) 65% forage, 35% concentrate. The forage portion was 58% brown midrib corn silage, 42% alfalfa haylage.
Cows fed brown midrib silage prior to calving also ate it after calving. Likewise, cows that ate conventional corn silage did so pre and post-calving.
Satter reports that cows fed the brown midrib diet produced an extra 5 lbs of 3.5% fat-corrected milk/cow/day than those fed the other diets.
"The cows responded very nicely to that higher forage diet when brown midrib silage was present compared to conventional silage."
Production was similar among cows fed the two rations with conventional corn silage.