A perfect loaded and mixed ration has a high consistency within and between batches.

Why is the mixing quality important?

The goal of mixing a ration is to minimize any variations in moisture, particle size, nutrients.  This stops cows being able to sort feedstuffs at the feed fence and ensures a more consistent feed intake which results in a more stable pH in the rumen and lower risk of rumen acidosis. 

How do we improve the mixing quality?

The mixing quality is influenced by the particle size of the feedstuffs, the loading order of feedstuffs, the amount of feed loaded in the MFR and the MFR knives. 

- Loading order of feedstuffs

Lely has defined guidelines for the loading/mixing order to achieve a homogeneous mixed ration. Feed types with the following characteristics should be loaded in the following way:

- Long particles & dry roughages: make sure that long particles and dry roughages are loaded first.

To prevent cows from selecting in the ration, particle sizes must be reduced. To do this, knives in the MFR will cut the material to a smaller size, but this takes a little time. Load long particles first to give the MFR enough time to mix and cut.

In order to make sure that dry voluminous materials are cut enough and do not cause ‘overcooking’ of the MFR, some pressure from more heavy feedstuffs is needed. Therefore, it is wise to load light, dry volume feedstuffs before wet feedstuffs with a short particle length.  

- Silage feed (e.g. grass & legumes): usually packed in a clamp or bale and contains flakes which are hard to loosen. Add these feed types early in the loading process to give the MFR enough mixing time. If needed, increase the post-mixing time to improve ration consistency and feed selection.

- (Wet) by-products: easy to mix and can increase the stickiness of the mix. Add the wet by-products before loading the concentrates/minerals to make sure they stick to it when loaded.

- Concentrates and minerals: sink easily to the bottom of the bin due to their fine texture and size. Make sure concentrates/minerals are loaded when the bin is >50% filled. Cows prefer concentrates and like to select them out of the mixed ration. The aim is to stick concentrates/minerals to other feed types to prevent the cows from eating selectively.

- Liquids: the total DM% of the ration effects the stickiness of the ration, to bind concentrates to longer particles. Liquid feeds have a positive effect to this as long as it is spread equally over MFR. Load liquid feeds in the second half of the loading process, depending on the existing DM%.

- Corn silage: mixes easily throughout the total ration and applies pressure on the other feedstuffs, which has a positive effect on the cutting and mixing of other feedstuffs. We advise loading corn silage as one of the last feed types so the MFR can use the corn silage loading time to mix the concentrates/minerals properly through the ration.

- Particle size of feedstuffs

All the different types of feed have their own characteristics. Characteristics such as scratch, structure, taste (sugar, salt) and length of feed ingredients determine not only the feed intake and digestibility, but also the mixing process in the MFR.

Long feed (particle size >100 mm) clumps together, contains flakes that are hard to loosen and make the feed mixture more intertwined in general. Large amounts of long particle feed types affect the capacity and mixing result.

Medium feed (particle size 50 mm – 100 mm) still have a tendency to clump together, but needs less mixing time to come to a consistent mix. There is still a risk of particle selection at the feed bunk, depending on the stickiness and entangling of the material.

Short feed (particle size <50 mm) is easy to mix in the MFR. If the largest particles in the ration are in this category, a ‘short feed auger’ (increased upward flow) is recommended.

Very small particles such as minerals, concentrates (powders), etc,. are very easy to mix. Important here is that these small feed types stick to longer particles. Adding water/liquid additives can improve the stickiness of small feed types to longer particles.

- Batch size

Proper mixing requires that ration ingredients fall into an open space created by the mixer screws in the MFR. The mixing quality decreases rapidly if the total batch/load exceeds the max capacity of the MFR. Overloading also leads to ‘overcooking’ of the bin, which causes more waste feed and cleaning tasks.

Too small batch sizes can also lead to improperly mixed rations due to a lack of resistance in the bin. The feed will flow around at the same speed as the auger is spinning and no upward flow is created. Adjust your smallest ration/feed location to a minimal batch size of 200 kg to ensure a good mixing quality. 

- Knives

Mixing augers that mix rations with roughage commonly have sharp knives to cut the long particles up in smaller particles. The knife blades wear in a few months, depending on the intensity of use. Blunt knives negatively affect the mixing consistency and increase the required mixing time. Make sure knives are sharpened frequently or replace them on time.

How can we judge the mixing quality?

The most commonly used method to check the mixing quality is to determine the particle size and consistency. This on-farm assessment can quickly be performed on a frequent basis using the Penn State Particle Separator box or ‘Shakerbox’. Please contact your local FMS advisor for support.