Ensuring a consistent ration

From auger speed to level loading, many factors influence the quality and consistency of a total mixed ration. Conducting a TMR audit can provide clarity on what areas need attention.

“TMR audits are crucial,” said Austin Sears, regional sales manager at Diamond V. “There are four types of rations — the one formulated by the nutritionist, the one that is mixed by the feeder, the one that is delivered to the pen, and the one that the cow eats.”

Sears was featured on Professional Dairy Producers’ “The Dairy Signal” in November, where his talk was entitled, “Audit Your Mix, Feed with Precision.”

The objective of a TMR audit is to review feeding practices to ensure consistency in diet preparation and delivery.

Sears said there are 11 primary factors that influence diet consistency: mixer wear/maintenance, being level when loading/mixing, hay/straw processing, loading position in the box, mix time after last ingredient, auger timing, auger speed, ingredient load order, liquid distribution, load sizes and forage restrictor settings.

When doing a TMR shakeout, Sears said they take 10 samples per load.

“We’ll watch a load get mixed and then follow it to the specific pen that it will be unloading to,” he said. “We pull samples from throughout the bunk to look at consistency from the beginning, middle and end of a load.”

They then calculate the coefficient of variation, with a goal of 3% or lower, Sears said.

Key areas to ensure proper mix action in a vertical mixer are the kicker plate or shoe, maintaining a tight tolerance to the tub wall, feed freely falling, the auger speed or rotations per minute, auger timing, auger thickness and knife wear.

“We want to make sure this feed box is doing what the manufacturer intended it to do,” Sears said. “Depending on the number of loads and size of your farm, parts can wear out quickly. … Before we know it, we’re feeding a diet that is not intended for the cows.”

A ring of feed on the outer edge of a mixer or excessive feed on the bottom after a load has been delivered is indicative of worn kicker plates.

“They’re designed to help lift that feed onto the auger so it can have that rising action,” Sears said. “Every manufacturer has a different spec that we can look at to make sure they are the correct length, height, and pitch angle.”

Routine maintenance on mixers also includes the removal of debris from inside the mixer.

“It is critical to take the time to keep these clean,” Sears said. “That will help the feed mix appropriately and provide a quality, consistent mix.”

Sears recommends checking the kicker plate wear and the distance from the mixer wall.

“Make sure these parts are in the correct areas and that they’re handling the wear and tear,” he said. “Sometimes it even requires replacing augers.”

Auger timing is essential, and if kickers meet in the center of the mixer, feed does not mix well.

“Each auger is specifically set in an orientation to where they mix together correctly,” Sears said. “These can be misplaced when they’re added or if we’re changing out our augers and adding new ones and doing it in house, the mechanic may not know the orientation. … (Then) we have two kick plates meeting in the middle, fighting against each other.”

Every manufacturer has different recommendations for auger timing and speed. 

“You need adequate velocity to allow for feed to mix,” Sears said. “Faster auger speeds mix better. Slower, longer mixing speeds can result in the diet ‘coming out of mix.’”

Sears said many times producers are not mixing feed at the necessary velocity and speed.

“There’s a lot of densities and a lot of forages in there, and we need to ensure those are mixed appropriately,” he said.

Forage restrictors, which were incorporated in mixers to help break down forages, create friction inside the mixer, which can create dead spots. Sears recommends pulling restrictors out as far as possible.

“We don’t see as many dead spots in the mix when those are pulled out,” he said. “We have a more even, consistent mixture, and (coefficient of variation) percentages stay lower.”

When it comes to hay and straw processing, Sears said to make sure hay is consistently processed to the desired chop length, which is often related to knife maintenance. Poorly processed forages create sorting issues.

Sears said there should be a protocol in place to replace knives and recommends checking knives weekly. For larger dairies with more wear and tear, knives may have to be replaced on a monthly basis. On a smaller dairy, they could last six months.

“We never recommend changing them all at once,” he said. “That can cause major issues with the ration.”

Sears said he recommends replacing bottoms and then moving those knives up the auger flight as they wear out to reduce chances of having an over-processed ration.

Making sure feed boxes are level when mixing is another important factor Sears said because ration densities are affected by an uneven pad.

“One of the biggest opportunities … is to try and improve our feed pads and make sure we have some spots that are level,” Sears said. “Grab that can of yellow spray paint and paint a line on the asphalt so (feeders) know exactly where to stop.”

Sears also stressed the importance of center loading for ration consistency.

“Usually, it just takes a quick reminder to let people know we need to be dumping in the center of these mix wagons to ensure feed has time to get around those augers,” Sears said.

When determining the ingredient load order, Sears said a farm should consult with its nutritionist. General recommendations are to start with hay/straw, giving it ample time to be processed well; followed by lighter, drier commodity ingredients like grains. Next would be wet, denser commodities like wet beet pulp; followed by forages and then liquids.

A final mix time of 2-3 minutes is recommended to allow the diet to mix effectively, with timing depending on load size and mixer capacity.

Hand-add ingredients, such as additives, must be added when the amount is at least 2% of total load size. For example, if adding 50 pounds, the total load size must be less than 2,500 pounds.

For distribution of liquid products, Sears said the goal is coverage of at least two-thirds of the mixer length.

“Adequate water application is one of the things we recommend,” he said. “A lot of times, it’s relatively inexpensive to fabricate and is really impactful.”

Ingredients must be above the top of the auger and below the base of the top of the mixer for optimum mixing. As cow pens increase and decrease in size, appropriate load sizes can be miscalculated.

“Very rarely do I ever see too small of a load; it’s always way too big,” Sears said. “It pays dividends to do it correctly and make sure loads are accurate for what our mixers are capable of.”