Silage production is not one-size-fits-all. What dairy producers ultimately want is more milk, and what beef producers want is more yield. However, there are some similarities with regard to what to watch in order to reach your goal. 

Taking a Silage Sample 

It's never a good idea to walk up to the face of a bunker silo and take a sample, mainly for two reasons. First, it’s not safe and you could be seriously injured or even killed. Second, it doesn’t provide a good sample due to forage variation within the silo. 

“Peel down the face like you normally would for daily feeding, and take at least five double-handful samples from across the silage you pulled down,” said Randy Shaver, professor and Extension dairy nutritionist at the University of Wisconsin. “Put those in a large bucket or tub and remix, then fill up at least a quart sample bag from that composite and send it to your laboratory.”  

Randy Shaver, professor and Extension dairy nutritionist at the University of Wisconsin

Corn silage can be difficult to sample due to the variation in particle size and density between kernels and fiber, so it’s important to take a large enough sample. 

Dairy Ration Analysis

Of key importance to dairy nutritionists in corn silage analysis are dry matter, neutral detergent fiber (NDF) and starch. Dry matter analysis can be done on the farm using either a microwave, Koster Moisture Tester or a portable NIR (near infrared) device. Dry matter testing is typically done at least weekly, or any time the feeder perceives that the dry matter content is changing.

“Feeding consistent proportions of dry matter in the ration is critical. If corn silage is wetter, feed more to get the same amount of dry matter; and if the forage is drier, feed less to get the same amount of dry matter,” Shaver said. 

The highest variation is seen in NDF and starch content. Some of that variation is real variation, but there are also sampling and analytical errors that can occur. Because of this, many nutritionists have begun reformulating rations on a three-week rolling average of analyses rather than one single sample result.

“If corn silage is lower in NDF and higher in starch, the nutritionist will recommend a ration with less corn grain. If it's higher in NDF and lower in starch, then they'll bring in more corn grain to maintain the consistency of the total mixed ration.” 

Beef Silage Ration Dependent on Management System

On the beef side, Daren Redfearn, associate professor at the University of Nebraska-Lincoln, recommends taking silage samples in each field where there’s a different hybrid or type of management. An example would be manure applications in some fields but not in others. 

“Beef producer feed-out depends on their system and whether they're feeding growing calves, which requires similar management to dairy with a focus on quality,” Redfearn said.

Daren Redfearnassociate professor at the University of Nebraska-Lincoln

Taking samples upfront can offer an idea of dry matter content prior to ensiling.  Moisture at harvest should be between 60% to 70%.

“Primarily, dry matter at harvest can affect fermentation. If the silage is too wet, there’s the potential for seepage, which will result in nutrient loss,” Redfearn said. “If it's too dry, silage will heat up and cause an increase in the acid detergent fiber (ADF) and NDF, which will decrease digestibility. Dry matter drives quality and therefore drives feed value.”

When selecting a silage hybrid, the easy option is to pick a hybrid with the highest grain production, but yield by itself is not the best indicator of silage quality. 

“The grain will make half of the whole silage yield. But the vegetative plant components will vary in fiber digestibility, digestible NDF and starch digestibility,” he said. “This comes back to feed-out management and whether you are feeding mature beef cows, where digestibility is less critical, or growing calves, where nutrient value and whole-plant digestibility are important.” 

Particle size is also a factor to watch. The standard range is ⅜" to ¾". If the cut is too fine, seepage could occur. If it's too coarse, it won't pack as well and poor fermentation may result.