Cow Chow: Six Tips to Master this Year

Key factors for your best silage harvest season ever

By Paul Hermans

Talk to any livestock producer and they will tell you they get two shots at making a great crop in one year. One during the planting/growing season and the second at harvest.

Silage harvest season is here. Maximizing quality will mean lower feed bills, healthier herds, and higher milk/beef production at the end of the day. A win/win for every producer!

The key factors for putting up quality silage include moisture considerations, length of cut, processing effectiveness, storage, chop height, and fermentation of the crop.

Mother Nature controls a lot of this, but you, as producer, can control various management techniques to maximize yield and quality. As you review these top six points, ask yourself “what did I do during last year’s harvest, which I could change this year, to make the best cow chow possible?”


Over the years, silage moisture ruled when it came to storage structure type and harvest timing. Recent research has shown us that increasing starch is the driving force behind great silage. With processors and larger equipment, we can efficiently put up higher valued corn silage by allowing the milk line on corn to progress farther.

corn field
    JJ Gouin/iStock/Getty Images Plus photo

Starch content will increase 0.7 percentage units for each percentage increase in dry matter. Whole plant dry down can occur at 0.5 to one per-centage points of moisture per day.

With a well-maintained processor aim for 1/2 to 3/4 milk line. Studies have shown increase milk production for 3/4 milk line silage harvests. Today’s excellent stray green hybrids (plant health) allows for more mature grain content in silage while maintaining optimal moisture content.

When monitoring milk line progression keep in mind it typically takes about one week to move through each quarter milk line phase. Think back to when your corn silage was tasseling – approximately 45 days from that date your corn silage should be at 1/2 milk line stage.

Other techniques that can be used to monitor milk line progression include getting Growing Degree Unit (GDUs) data for hybrids for tassel predictions. Talk to your seed supplier for specific hybrid data. Using online weather tools allows you to simply calculate days to 1/2 or 3/4 milk line from a given calendar date of recorded GDUs ensuring more energy in every bite of silage.

To monitor milk line progression, pick representative parts of your field and pick 10 typical ears to check for milk line. Alternatively, new tools like satellite imagery or crop zones (from previous maps, SWAT or VERIS machines) can be used to assess field variation.

Split the cob in half, halfway down the cob. Visually look at the milk line of the kernel in your hand, holding the ear tip. A visual assessment can sometimes be misleading. Chewing or biting into an individual kernel or using a ball point pen and marking the transition point between liquid and solid starch may be more indicative of milk line progression.

Length of Cut

Length of cut is critical for cow rumen function. Compared to corn silage, alfalfa is cut shorter to aid with fermentation. This allows growers to maximize the length of cut for corn silage to make for a more uniform total ration based on what is put in front of your cows.

Hand holding chopped silage
    Check your last year’s harvest for length of cut. Was it variable or not? - jess311/iStock/Getty Images Plus photo

The theoretical length of cut for processed corn silage can be set at 3/4” long. This is longer than the normal 3/8” to 1/2” length obtained from none-processor harvesters.

To balance this out longer lengths of cut with corn silage is advisable. Talk to your nutritionist about your total ration and how adjustment of silage prior to actual harvest can aid with better rumen health. Take a shaker box approach to assessing last year’s harvest to score yourself on how well your length of cut is and is it variable or not.


Processing silage is key to happy cows! Utilize a corn silage processing cup (32-ounce or one-litre milk jug) and keep it in the chopper with you. At the start of each day or when changing hybrids, fields or planting date within a field, do an assessment on processing quality. Spread the collected sample out and assess each kernel. All kernels should be completely fractured, not just nicked, to allow for optimum rumen uptake. If you have more than four whole or 1/2 kernels in the sample cup not processed, take the time to adjust the harvester. This is critical in achieving the highest quality corn silage you can.

cows eating silage
    Maximizing silage quality leads to healthier, more productive cows. - Diane Kuhl/iStock/Getty Images Plus photo

Processor maintenance is critical to achieving well processed corn silage. Worn shear bars will change uniformity and length of cut. Worn roller mills may prevent narrowing of the roller gap. Ideally gap width should be 1 to 2 mm to ensure proper cracking of all kernels. Roller mill differential is also an important part of proper processing. Review your owner’s manual for ideal chopper settings.

One touchy subject continues to be custom silage choppers. The goal of the custom operator is to keep you happy then get on to the next client and their long list of harvest needs.

If you have a custom chopper doing your corn silage, it pays to ensure the chopper slows down to meet quality standards.

A tough but well worthy discussion to be had well ahead of stressful harvest schedules will ensure you are happy with the end result. They may charge more for excellent processed corn silage, however, your cows will appreciate the extra quality focus and reward you with higher production levels.

Structure Type

Storage structure (ag bag, bunker, upright) will determine harvest schedules based on moisture. Do not forgo additional starch gains by chopping corn silage too wet. Adhere to sound principles to maximize starch levels.

For bunkers, a few key principles come into play. Layer your corn silage like you would pavement. This ensures an excellent bulk density and less loss due to air pockets and bad yeasts. Have the ideal tractor weight based on harvest tonnage per hour to achieve this. By packing each layer carefully, we can reduce the amount of air that penetrates deep into the pile. Air is the enemy – air allows the bad bugs to activate and will result in spoilage and heating.

A big rule of thumb is to not overpack the silage, especially the last few loads, as your will “crush” the cells of the silage, causing a layer of excess moisture which will negatively affect fermentation. Overpacking the top layer will not make up for underpacking the lower layers. Take the time to pack each load sufficiently.

Chop Height

If you are trying to maximize digest-ibility, consider raising your silage chop height. Raising your chopper four inches can improve digestibility by five to 10 per cent. Offsetting this is lower yield (one ton/four-inch height difference). Review current feed inventories and the next 365 day feeding plans prior to adjusting chop height. What is more important: silage yield or high-quality starch, or a combination of both?

Prior to harvest you can take representative chop samples in the field and run digestibility NDFD values. Chopper height can be adjusted from utilizing these values and other management goals.

Keep in mind, research has shown that growing environment (hot/dry vs. cold/wet) plays a bigger factor on digestibility than all other factors combined. Yes, hybrid selection is important for digestibility traits (example: brown midrid vs. non-BMR corn hybrids).

At the end, it is Mother Nature and the growing environment from planting to harvest that has the biggest impact on digestibility.


Fermentation aids such as inoculants have significant payback, especially as feed prices rise. Crop specific bacteria reduce the pH in your silage – in essence pickling the crop for cow feed. These bacteria need energy to complete this process. Think about the bacteria that help lower pH in your silage – they are smart. These bacteria consume the highly available energy sources like starches and oils first. Just like a dinner buffet you might visit on occasion, ask yourself “do I load up on leafy items more than on meats and desserts?” If you’re like me, the high-protein, high-tasty sweets are what I choose.

If we can “supercharge” this fermentation process, we can reduce the energy the fermentation bacteria need. According to Ashley Knapton, dairy strategic accounts manager with Corteva Agriscience, research data has shown we can save 10 to 15 per cent shrink loss by using a reputable forage inoculant.

“Producers are doing an excellent job storing their feed on-farm, and inoculants help take that job from good to great,” says Knapton. “By fueling that fermentation process, we can conserve the nutrients that we worked so hard all season to grow for the cow who will use them best.”

With today’s commodity prices the value of lost silage adds up. For example, if we take a tonne (2,200 pounds) of grain corn this equates to about four to six bushels of grain corn loss using our 10 to 15 per cent shrink loss. At today’s corn prices a reputable inoculant will have a return on investment of 15:1. Imagine if all our investments would accomplish this.

In summary, take time to walk your fields to get a handle on maturity progression. Sit down prior to the busy harvest season and talk to your nutritionist, seed expert, chopper operator and other influencers involved in your farm operation to develop a sound harvest plan. Your cows will be glad you did.

What you do from a harvest standpoint over the course of a few days will affect your cows for the next 365 days. Let’s make sure you make the best cow chow you can! BF

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