Lab feed, manure data

Ray Mueller
Now Media Group


Even if dairy farmers are already enjoying good milk production from the mixed rations that they feed to their lactating cows, there is probably some room for improvement.

And many other dairy farms have lots of room for improvement on that point, Sheboygan County dairy farm native John Goeser assured attendees at the 2015 dairy cattle feeding day, sponsored by the Manitowoc County Forage Council. He is director of animal nutrition and research and innovation at the Rock River Lab at Watertown and is an adjunct professor of dairy science at the University of Wisconsin-Madison.

Goeser bases his observations on the thousands of data sets compiled at the laboratory from feed and manure samples submitted to Rock River by dairy farmers in Wisconsin and beyond. He suggests getting a feed analysis at least twice a year, particularly when there is a switch from one feed batch to another.

Margin opportunities

In addition to the mixed ration samples of one pound from five places in a batch and the fecal samples in a combination from about 10 cows (sample costs of $20 to $25), Rock River offers a full comparative analysis of ration and fecal samples to calculate the digestion percentage for a fee of $125 — or about 1 cent per day for 100 cows to cover a period of four months, Goeser pointed out.

Those analyses can identify 'margin opportunities' such as 5, 10, or 15 cents per hundred of milk production, 5 more pounds of milk production per day for many cows, or reductions of up to 40 cents per day in feed costs per cow, Goeser indicated. The latter scenario was achieved in a herd averaging 100 pounds of milk per day by increasing the forage portion of the ration by 5 percent, he explained.

In other cases, putting feed additives in the ration will lead to improved margins, Goeser stated. He mentioned microbials and enzymes as among the several possibilities.

Removing bottlenecks

Before taking such action, however, Goeser suggested that removing one or more bottlenecks that impair dairy cow production and affect their health should take place first. Because 'cows know bad forage,' it should be a standard practice to discard spoiled feed, which is likely to contain molds and/or mycotoxins, rather than trying to blend or dilute it, he emphasized.

Another bottleneck can occur in the quality and physical condition of supplement byproduct feeds, Goeser observed. He shared a picture of seven sample bags of distillers grain which exhibited great differences.

The laboratory test results can be very valuable in addressing bottlenecks because they show what portion of the feed is digested and directed to milk production, Goeser advised. Based on the testing data, it is not unusual to find that between 50 to 70 percent of the energy in the ration is being used, he reported.

Differences of up to 30 pounds per 100 pounds of feed, which are digested for their energy value are sure to convert to major differences in milk production, Goeser stated. Every 1 pound change in how much of the ration is digested means about a 1.5 pound difference in daily milk production, he said.

Both fiber and starch are involved in the digestion percentages, Goeser noted. There are situations in which up to 60 percent of the fiber is not digested and goes into the fecal matter instead, he pointed out.

Starches are digested at a much higher rate in the rumen but even a 6.5 percentage point deviation from 92 percent is very significant, Goeser remarked. His standard is to find only 2 percent of the starch in the fecal matter — a goal that is met or exceeded by only about 20 to 25 percent of the fecal starch content tests run at Rock River Lab. When the standard is 98 percent for total digestive tract digestibility, very few of the samples meet it, he reported.

With the feeding of corn silage made in 2015 having just begun on many farms, Goeser is concerned about digestion of starch because of relatively hard corn kernels which went into the silage made last year. He suggests a fecal starch analysis at least annually or preferably twice a year.

Rock River's data from 2014 shows how much difference there can be within feed ingredients on the percentage or starch digested in the rumen of dairy cows, Goeser pointed out. The respective averages and percentage point variations identified in samples were 56 and 26 for high moisture shelled corn, 50 and 22 for dry ground corn, 75 and 28 for corn silage, and 60 and 30 for total mixed rations.

Goeser observed that the sizes of dry ground corn are ranging between 400 and 1,400 microns (700 to 1,000 are recommended) in the samples sent to Rock River. Raising the percentage of starch digested in the rumen to 80 percent from 60 percent should boost daily milk production per cow by 5 pounds, he promised.

To a question about shredlage, Goeser said it has more consistent digestion than conventional corn silage and that it packs somewhat better in bunkers. With conventional corn silage, a longer period of fermentation improves the starch availability in the corn kernels, he added.

Goeser is confident that the growing environment is responsible for 50 percent of the differences in the digestion of corn. Other factors that he lists are the seed/hybrid genetics, maturity at harvest, dry matter, kernel processing, ensiling practices, rumen dynamics, and anti-nutrition (spoilage).

Dairy farm examples

For one dairy farm where total nutrient digestion was 69 percent and the starch digestion was 87 percent, Goeser noticed that the supposed 'high moisture' corn was too dry. Once it was ground, the result was a daily average increase of 5 pounds of milk per cow.

On another farm, total nutrient digestion was only 60 percent (33 percent for fiber and 96 percent for starch), butterfat was low, and cases of displaced abomasum were increasing. Goeser traced the problem to poor quality corn silage, which was addressed by growing a different hybrid and also followed by a 5 pound daily increase in milk per cow.

Goeser can be contacted by e-mail at, on his office phone at 920-261-0446, or @johngoeser on Twitter.