To process or not? That is the question with alfalfa

Mike Brouk, Kansas State University professor and state dairy Extension specialist, studies the effect of pre-cutting round hay bales during baling on forage quality and processing time.

He recently finished a field trial looking at this subject. He shared pertinent findings during the recent Alfalfa U event sponsored by John Deere, Alforex and High Plains Journal.

There are baler models available that slice the forage as it’s wrapped into bales, and Brouk wanted to see if tub grinding could be eliminated from the feeding process, as well as the forage losses that are associated with it.

“In doing this we also wanted to monitor to see if we were having any impacts—positive or negative—on the forage quality of the material that we were baling,” he said.

He worked with four beef operations in southeast Nebraska and with John Deere on this project. They used the same baler—a John Deere 560M—on all four farms and it was moved from farm to farm during the trial. Blades were set to slice the forage every 6 inches as it came into the machine. The only setting that changed on the baler between cut and normal bales was moving the knives back out of the way so they did not touch the forage.

“So all of the tensions and everything remained the same,” he said.

They replicated the process at each farm so they had six bales that were sliced at baling and six left unsliced.

“The way we accomplished that is we would bale an unsliced bale first. Stop, kick that bale out, set the knives in and then bale a sliced bale,” Brouk said. “As we went down across the field, through the windrows, we were alternating the bales sliced or unsliced. As we did that, we would produce a total of 12 bales per farm.”

The resulting bales were stored for about five to six months prior to removing them from storage. At baling, bale weights were obtained.

“We have a scale that we constructed so we could actually obtain accurate weights of each bale in the field,” he said. “We also did some measurements to look at length and diameter and then we took forage quality samples.”

Forage quality samples were obtained by sampling the outer 6 inches of the circumference of the bale and the inner 6 to 18 inches.

“So for forage quality analysis we actually did look at the outer layer versus the inner layer,” he said. “And we also did that, after five to six months of storage so we reweighed the bales. We did all the dimension measurements and then we did the core samples and again divided those into the outer 6 inches and then 6 to 18 inches inside.”


Initially when Brouk looked at the bale weights—comparing the non-sliced to the sliced—he found those bales with forage sliced at baling weighed significantly more than those that weren’t sliced.

“As we slice, you can imagine we’re making a smaller particle size,” he said. “We can probably get any increase in the amount of material that we can get in that same size bale with those same settings.”

That’s likely what Brouk saw, an increase in density. The cut bales had greater density than normal compared to the uncut. This could indicate as the particle size is reduced within the baler with the cutting action of the knives, more material was packed into each of the bales.

“If you’re thinking about efficiencies—it might be an opportunity to gain a little bit of efficiency here because we’re packing more material into a single bale we have fewer bales to move off the field,” he said.

An argument can be made that there’s more material inside the bale because the settings were changed.

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“We could have done that, but again for the purposes of the study, we really wanted to understand better what was the effect of slicing that material versus not slicing material during the baling process,” he said. “So that’s the reason we chose not to change other settings on the baler.

As he looked at the baling rates, he looked at time and motion and was able to compare the actual baling rate or the rate at which he was able to produce bales. There was technically no difference between the cut and normal bales as far as dry matter per minute packed into the bales.

“I think the take home here is that using the cut option does not slow down the baling process,” Brouk said. “Sometimes we have some concerns, possibly as we add these types of processing to something like baling—we’re actually slowing down the baling process and think we can really share from our data that did not occur and we were able to maintain a similar bale rate as to normal bales.”

From the data in the inner and outer core samples averaged together, Brouk found after this study, immediately after baling there was a slight change in the neutral detergent fiber and acid detergent fiber constants. There were some changes in lignin, but that could go along with the ADF.

“So it’s not unusual that we’d see that,” he said.

It ended up being a really tight data set, even though all the samples were analyzed by the same lab. Brouk said this helps remove some of the “noise factors.”

“We kind of removed the possible interference from lab variation,” he said.

As far as what was lost, he believes it’s possible that there were some problems with leaf loss, although it wasn’t noticeable on the ground, “because we did look on the ground.” He found no real visible difference between the two types of bales.

“I have a bit of a concern when we think about the hay probes that we use to take these samples,” he said. “If we have a smaller particle size in those cut bales—which we did—you should push that probe down through there, there could be some separation that’s going on in sampling that could have resulted in this difference that we see.”

But these are very, very small differences, according to Brouk.

“They were significant, but are you going to be able to actually see that in a feeding situation or animal performance?” he said. “I really don’t think probably we can. So just kind of keep that in mind that this could be a sampling issue as opposed to an actual leaf loss situation with baling with cuts.”

Interestingly enough, the NDF digestibility did not differ, Brouk said.

“If we were having a slight effect on fiber levels with the cut treatment, it was not having any impact on the digestibility,” he said. “I think from a fiber utilization standpoint I think this is pretty important that we did not negatively impact that with the treatment.”

He also took a look at storage and processing losses. Shrink on these bales wasn’t significant, but was a trend he found.

“Shrink was less for the cut bales,” he said. “That was due to the fact that we had a higher density with those bales. Again the bales were all stored similarly at each farm.”

Conditions remained the same for the normal and for the cut bales on each individual farm for both treatments.

“Our cut bales at least numerically seem to have less strength during that storage period,” Brouk said.

He also evaluated the fiber levels. After sampling following storage, the bales were processed and they sampled the outer 6 inches as well as the inner 6 to 18 inches. He found that over time during storage the ADF content increased slightly, and that would be expected since the bales weren’t protected from the weather—having a greater impact on the outer layers.

“Again, when we look at loss of nutrients or changes in forage quality and round bales stored outside, much greater impact on the outer layer than inside the bale,” he said. “For more steady a bit of increase in fiber level we actually went down deeper into those bales—same situation with the lignin content.”

As for processing, the cut bales went through a TMR mixer, and there was a much greater percentage of the material that was greater than three-quarters of an inch, with much less being left behind in the pan as fines. Those feeding animals forage need to consider this aspect of it, especially those who are dairy producers.


Bottom line, how does Brouk interpret his findings from this research?

With the precut bales he saw an increase in bale size and density. There were some small increases in fiber concentration in those pre-cut bales.

“As we look at the last part of the study where we actually process these bales as we might normally do on a farm, we can see that if we put the pre cut bale into the mixer wagon directly, as opposed to running bales through the grinder there’s going to be an increase in processing time,” he said. “Probably less though than trying to put an uncut bale into the TMR wagon and process it that way.”

There was also a reduction in shrink by eliminating the hay grinder from the situation and doing that step in the total mixed ration wagon.

“We did continue to see that slight increase in fiber content and I really think that may have really been associated with the sampling issue, as opposed to an actual issue induced onto the situation by the baler,” Brouk said.

He hopes to return to this research and try to assess why there was a slight increase in fiber content.

“Again, while it’s statistically significant in an animal and you’re going to be able to detect differences in animal performance from feeding hays produced from the cutting during the baling process, I really don’t think from our data that we could be confident in saying that there would be differences there,” Brouk said.

Kylene Scott can be reached at 620-227-1804 or [email protected].