How much corn silage should I feed? That is a question often asked by dairymen in the last several years. In the 1980's and early '90's many Midwest dairyman were feeding predominantly haylage-hay rations, with very little corn silage. Before 1985, very little credence was given to the importance of amino acids and rumen undegradable (bypass) protein. Ration balancing simply used "crude protein" and alfalfa provided a high level. These diets reduced the cost for purchased protein.

Production Level A Factor
In the 1970's, herd averages of 16-18,000 were considered quite profitable. A herd of 20,000 was exceptional. It was in this time period that haylage became the forage of choice, as baled hay was quite labor intensive. Most herds utilizing feed testing and ration balancing could achieve production goals with soybean meal as their only purchased protein source. Most dairymen still purchased commercial protein blends and did not routinely test their forages.

By the early 1980's, a 20,000 pound herd average became a reasonable goal for most producers, and now 25,000 appears to be the benchmark. These higher production levels require proper bypass protein sources that meet Iysine/methionine requirements.

Corn Silage Advantage
From a ration standpoint, corn silage helps dilute down the excessive rumen degradable protein present in high quality haylage diets. It also helps increase the energy density and decreases the amount of corn or other energy sources required for high production. Its biggest advantage may be increased dry matter intake. After all, cows like corn silage!

There are many economic benefits from a cropping standpoint. Yields are around 20 tons per acre (7 tons dry matter). Corn works well in cropping rotations with alfalfa. In many area's winterkill of alfalfa is high, so feeding more corn silage can be nice insurance. In area's where a lot of corn is raised for grain, decisions can be made by late August if more corn silage is needed. It is generally easier and more economical to purchase corn for grain than for corn silage.

Challenges
Because of these advantages, many producers have changed to high corn silage diets, which creates a new set of problems. Besides the high amount of purchased protein required, digestibility of corn silage becomes a big variable. It's the most difficult ration parameter to measure. Invariably, the visible corn in the manure comes from the corn silage. In years past, most producers put up corn silage too mature. This results in the harder, whole kernels, thus the grain in the manure.

It has always been ANC's recommendation for producers to include corn silage in dairy rations. Even as little as 10-15 pounds makes a difference when balancing protein and energy fractions. High corn silage feeding always has been a problem because of kernel digestibility. Throughout my career I have always been an advocate of making corn silage early when the kernels were soft and the plant green. This can result in 70% moisture which is not a problem for bunkers or bags, but can lead to some frozen corn silage in upright silo's, however, cows will milk better on this than drier 60% moisture silage with a lot of hard, undigestible kernels.

Recent Research
At our National Meeting in early May, Dr. Larry Satter (U. of Wisconsin, U. S.D.A Forage Research Center) gave a talk on corn silage based on research at the U.S.D.A. Forage Research Farm at Prairie du sac, WI. The rest of this article will present findings on how much corn silage to feed and the effects of roller milling.

Three trials were set up utilizing these three forage ratio's on a dry matter basis:
100% alfalfa haylage
1/3 corn silage-2/3 alfalfa haylage
2/3 corn silage- 1/3 alfalfa haylage

How Much Corn Silage Answered
To keep it simple, the 1/3 corn silage diet appeared to have the most advantages, with the 2/3 corn silage diet second, and the all haylage diet third. The 1/3 corn silage diet produced the most pounds of milk, butterfat and protein and provided the lowest cost per 100 lbs. of milk. This does not mean that a diet with 1/2 of the forage dry matter from corn silage would not be comparable, but one would have to conclude that approximately 1/3 of the forage dry matter should come from corn silage.

Proper Harvest Time
Research from Washington State University and University of Wisconsin had similar findings on corn silage maturity vs milk yield. Harvest at 1/2 to 2/3 kernel milk line produced the most milk ( 100% of possible production), with 1/8-1/4 milk line corn yielding 97-98%. When the milk line development is complete milk yield can drop to 94%. It's better to err on harvesting a little too early than a little too late!

Rolling of Corn Silage
Satter's research involved several trials with rolling. One set of trials, where rolled corn silage was 1/3 of the dry matter forage, showed only a minimal production gain (0.60 lbs. milk per cow per day). On all corn silage diets, depending on length of cut, the milk advantage increased, ranging from 2.5-4.4 pounds. The protein and butterfat increased when finer cut corn silage was rolled, but not coarser corn silage. Dry matter intake also increased 2-4 lbs/ hd/day.

The next phase was to determine if rolling at harvesting was better than rolling silage after it came out of storage before it was fed. Pre-Rolled corn silage did produce more milk (1.5 pounds per day) than Post-Rolled making that our first choice. However, Post Rolled corn silage performed better than unrolled, making this an option if one could economically get a roller set up for feeding.

Summary
In conclusion, consider 1/3 of the cows diet to be corn silage on a dry matter basis. I know this figure will vary, but in studying rations we run, this figures to about 25-30 pounds of corn silage a day. Rolling looks promising, especially when a high level of corn silage is fed.

Other options include planting more acres of corn silage specific varieties, many of which are available at this time. I know that this will take good planning, because much of our corn silage is currently made from headlands and opening up of fields, along with parts of fields that look like they may not make good corn for grain. For years it seems that the corn companies forgot about corn silage, and efforts were concentrated on developing ears that dried down faster with the stalk still green to improve stand. However, tremendous advances are being made, and one should at least plan part of their corn acreage for silage varieties. Make sure to treat corn silage with a good inoculant. I recommend ANC Pro-Store! Innoculant research shows more milk produced, along with less dry matter lost!

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