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0408 PD: Get the most from your corn silage

Jerry Weigel Published on 27 February 2008

If we’re going to manage the dairy cow for optimum productivity and health, we cannot ignore the rumen. It is the center of all functions inside the cow. But keeping this vital organ working at peak efficiency is a delicate balancing act.

Microbes inside the rumen are responsible for breaking down feed and converting it into the essential nutrients used to maintain basic body functions, including milk production. These microbes love forages. The problem is that we cannot supply the cow with enough forage to help her produce to her genetic potential. So we need to supplement the diet with concentrates, primarily in the form of corn and grain co-products. The breakdown of these ingredients inside the rumen tends to create acids that are not beneficial to the rumen microbe population.

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So how do we achieve a happy medium? If we feed too much forage, the cow doesn’t have enough energy to meet production needs. And if we supply too much energy through corn and other grains, we upset the rumen environment and create a negative health situation.

What we’ve learned through recent research and on-farm studies is that the right ration can achieve high milk production and still maintain rumen health. This article will discuss how corn silage can help achieve that nutritional balance.

Why corn silage?
On some farms we’ve seen corn silage reach almost half the ration, and for good reason. New hybrids exist that are bred to exhibit traits that make corn silage a very attractive forage, especially in light of today’s high corn prices. Some of the positive attributes that corn silage offers include:

High-energy
It’s no secret that energy is probably the most important nutrient cows need throughout lactation to achieve high levels of production. After calving, energy is one nutrient that we are not able to provide enough of for cows to avoid losing body condition. The less time cows spend in the resulting negative energy balance, which is partially dependent on a high-energy ration, the more time they spend producing high volumes of milk without the looming possibility of metabolic disorders.

Corn silage may be a great alternative to more expensive energy sources. There are varieties available that replace lignin with effective fiber and sugar, which improves fiber digestibility and increases net energy for lactation (NEL). This allows producers to cut back on grain, creating a more reasonably priced ration.

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Palatability
Cows like the taste of corn silage, so quality corn silage can help boost dry matter intake (DMI). This is especially important for fresh cows because we have a hard time getting them to eat after calving. If we are able to boost intake during early lactation, we have fewer metabolic disorders and have an overall more profitable cow, not to mention more productivity throughout lactation.

Consistency
Dairy cows crave consistency in their day-to-day schedules, and this includes the feeding program. If harvested over a short time period, high-quality corn silage can be a very consistent part of the ration and ensure that each bite of the TMR is the same as the last. This consistency also benefits rumen microbes by encouraging a consistent population throughout lactation.

Easy-to-manage
In general, corn silage is easier to manage than other crops, especially when considering what it takes to manage multiple cuttings of alfalfa. Still, it’s critical for corn silage to be harvested at the appropriate moisture level and packed tightly to encourage proper fermentation. Because in-field moisture levels can change quickly, it’s also important to get the corn out of the field as quickly as possible to reduce variation.

Corn silage challenges
Even though corn silage is such an important part of the ration, there are a few challenges to feeding high levels of it to your herd.

Protein costs
Corn silage is low in protein, so additional protein will need to be supplied. The most common source of protein is soybean meal, which can be an expensive purchase today. Although other protein sources are available, the cost of quality protein can be quite high.

It is important to note, however, that if we grow the right corn silage varieties and manage harvest and storage correctly, we can reduce the need for excess protein. Some varieties are higher in protein than others because of their genetics. These varieties have higher protein in the kernels and since the kernels make up 40 to 45 percent of the silage, the corn silage will have an overall higher protein value. The silage hybrids with higher protein may help you remove some of the expensive protein, like soybean meal, from the ration.

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Health concerns
Too much energy can have adverse effects on cow health. Sub-acute rumen acidosis (SARA) can result from high-energy diets, usually caused by high concentrate levels. SARA can reduce DMI and result in lowered production. Lameness and poor reproductive function have also been linked to energy-rich rations.

Quality
Unlike alfalfa quality that can change from cutting to cutting, corn silage that is grown, harvested and stored correctly can be a good foundation for a stable ration throughout the year. But when you have low-quality corn silage, whether it be from poor weather conditions or improper harvest and storage, it can result in an unbalanced ration or expensive ration because of purchased feed ingredients. Diversifying the types of silage varieties in the field along with promoting proper storage and feed-out can help ensure your herd gets the best feed available.

Finding a balance
Feeding high-quality corn silage can help producers find that balance between high production and optimal rumen health. One way to know if this balance is being achieved is by reviewing management data and watching cows and their response to the feeding program. By monitoring production, intake and cow activity you can identify how they are adjusting to the ration. For example, if you start seeing more displaced abomasums, less cud chewing or a dip in production, make the adjustments needed to keep your cows on the right track.

It’s also important for producers to take advantage of corn silage hybrids that promote feed efficiency and rumen health, two areas where conventional silage varieties sometimes fall short. Research completed in 2005 and 2006 by Dr. Jim Spain, associate professor of animal science at the University of Missouri, found that cows fed hybrids bred specifically for high-quality corn silage produced the same amount of milk as cows fed conventional silage.

What’s important to know is that these cows also ate less feed, resulting in a 6 percent improvement in milk production efficiency. Microbes in the rumen also produced 13 percent more volatile fatty acids, a very good indicator of overall fiber digestibility.

The corn silage you’re feeding today bears little resemblance to the corn silage available to you even as recently as a decade ago. The advancements made in plant genetics and nutritionally enhanced traits make corn silage an important, consistent part of dairy rations that helps producers achieve a critical balance between productivity and cow health. PD

Jerry Weigel
BASF Nutrition Manager

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