The Feed Grinder Mixer, Friend, or Foe?

Dec 01, 2022

By Richard Purdin

For many livestock producers, the feed grinder is their most cherished tool.

You could say grinding feed runs in my blood. A matter of fact this was one of the first farm chores that I can remember helping dad with. If you were to ask a farmer what are the most vital pieces of equipment on the farm, you would probable expect to hear answers such as combine, tractor, skid steer loader, etc. For a farrow to finish hog, market steer, and feeder lamb operation, could there be a worse situation arise than the grinder mixer breaking down! There is not a day that the grinder mixer is not used on my farm and for many other livestock operations it would probably be considered one of the most used equipment on the farm.


It is thought that grinding grain for livestock feed started around 1860 and one of the first feed grinders invented was called the burr mill made by the Letz manufacturing company in Crown Point Indiana. By 1930 the hammer mill was created revolutionizing speed and quality of grinding feed. The grinder to this day is still highly used and the selling point remains the same – to make grain more digestible to livestock. As farmer, veterinarians, and livestock nutritionist learn more and more about livestock anatomy the improvements and modifications have been made to the feed grinder to help improve the operations of the feed grinder and avoid animal health issues that can arise from grinding feed too fine.

For both large and small ruminant producers there is a ongoing love hate relationship with feed grinders. And there is a debate whether they are truly needed? Processing or grinding grain has some bright sides such as increasing digestibility of grain. When large grains such as corn or small grains like wheat and spelts are processed by rolling or grinding the surface area of the grain is increased in the rumen. As the surface area increases digesting rumen bacteria will adhere to the grain and break it down rapidly. There are several different species of bacteria in the rumen the most well-known grain loving bacteria is called Streptococcus bovis. This species of bacteria is present in high amount in rumens of livestock fed high grain diets.

As the surface area of the grain is increased by processing or grinding these bacteria will produce high amounts of lactic acid, in turn making the rumen ph drop dramatically to levels below 5.5 ph. When this happens the animals’ blood ph will drop as well When the animals blood PH levels become too acidic this a chain reaction of reduced esophagus muscle movement will occur leading to restricted regurgitation or cud chewing all while fermentation continues. The Cud Chewing process is essential for the release of gasses from the rumen and when this process is halted to restricted bloat will occur. Bloat can be life threatening causing suffocation.

When the rumen PH drops too low another condition call acidosis can occur. There are two types of acidosis, chronic and acute. Chronic Acidosis is when cattle will go off feed to compensate for digestive upset. Chronic Acidosis is often called yo-yo cattle or cattle that eat a lot one day and then go off feed for a couple of days. Chronic acidosis can quickly lead to acute acidosis when cattle gorge themselves after getting over their stomachache! Acute acidosis quickly leads to bloat and death when left untreated.

Cattle feeders have struggled with bloat and acidosis for a long time and some question if the feed grinder mixer is still needed on the farm? So should grains be ground for large and small ruminant livestock? My goal was to answer said question at my field day, and after a quick demonstration with my personal feed grinder mixer I was able to stimulate thought and questions from attendees. What I found out is the answer is it depends! I believe the grinder mixer still has a place on a cattle farm but should be used with caution.

Some ways you can still utilize your feed grinder, sleep soundly at night, and keep your local feed grinder salesman in business includes the following best practices.

  • Roller mills vs Hammer mills– If you are looking at purchasing a new feed mixer look at roller mill options.
  • Remove the screen– If you are on a budget (like me) and want to still utilize your hammer mill grinder, remove the screen this will allow for cracking of the grain rather than pulverizing you could purchase a large whole screen 1-2” screens can be used for larger cracking.
  • Watch your tractor RPM- 540 pto driven tractors operating at 1800 rpms allow for proper processing. I recommend reading manufactures operating manual for proper operations Running tractor rpms too fast can lead to over grinding.
  • Proper mixing can help– Putting supplements and premixes in prior to grinding can allow for better feed mixing. Allow feed to mix for 3-5 minutes after grinding.
  • Don’t blame the grinder on poor bunk or feeder management– Take time to watch how much feed is left in bunks after feeding and adjust as needed. Don’t allow automatic feeders to run out and adjust doors to make cattle work for their food. If feeder wholes are fool to overflowing adjust the doors down!

In summary, I won’t be selling my feed grinder mixer anytime soon but I will be more cognizant on how I use it. Processing grain can help increase digestibility and improve animal performance when done at the right rate and amount. Building a good relationship with a nutritionist or veterinarian is important for maintaining animal health. Last but not least management can cure many health issues, watching your cattle closely at feeding and evaluating feeders, bunks and livestock stools prevent bloat and acidosis. Following all these steps can lead to a better relationship with your feed grinder mixer!

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