The importance of limiting the chance of sorting
A tasty portion with various feedstuffs provides an evenly mixed ration at the feed fence for your cows. This is usually the starting point for feeding your animals. You want to minimise sorting of the ration by the cows. Sorting results in an unbalanced intake of the ration and therefore a cow has a higher chance of suffering from subclinical rumen acidosis (SARA). Rumen acidosis is not only a periodic issue, it also affects the whole lactation performance of the cow.
Due to the unbalanced intake, the rumen constantly has to adapt to the varying proportions of the feedstuffs the ration contains. Sorting at cow level can also lead to lower fat and protein levels in the milk.
These sorting effects have direct and indirect consequences on your farm’s costs and income.
A dairy cow ration often contains different feedstuffs, each with its own characteristics. Therefore, it is not always an easy job to create a well-mixed ration. If you want to measure the mixing quality of the ration, you can use a particle separator box. Later in this article you can learn more about how to use the tool and how to judge the outcome.
Key points for a well-mixed ration
A well-mixed ration is more difficult for cows to sort. A few key points for creating a ration that is easy to mix are:
- Keep in mind the particle lengths of the different feed types in the ration. Roughage that has already been chopped during harvesting is recommended for easy mixing.
- Low-dry-matter feed types are easier to mix than dry feedstuffs like haylage.
- The goal should be to have the same particle length in all feedstuffs. This makes it harder for cows to sort their feed.
- The dry-matter level of the total ration is also important. A very dry ration is easy to sort. The concentrates do not stick to the roughage, so they fall through the particles onto the floor. Then the cows can sort the ration very easily. By adding water, the ration becomes stickier for the concentrates.
Evaluate the mixing process of the ration using a Penn State Particle Separator
An easy tool for checking the mixing quality of the ration is the Penn State Particle Separator test. With this test, you can separate out the different particle lengths of the ration. The Penn State Particle Separator contains four sieves with different sizes of holes. By using a special shaking method, the particle lengths fall through the holes and are separated precisely.
How to use the particle separator
Put the four particle separator sieves on top of each other in the following order: on top, the sieve with the largest holes; the medium-sized holes next; then the smallest holes as the third sieve; and the closed box at the bottom.
Put half a feed scoop (200 g - 300 g) of mixed ration in the top sieve. Bear in mind that the dry matter of the ration has an effect on its sieving properties, but analysis at a standard dry-matter percentage is not recommended. However, very wet samples (<45% DM) may not separate accurately.
It is recommended that you take three samples along the feed fence: at the start (where dosing feed starts), in the middle and at the end of the feed alley. Shake all of them separately to compare the outcomes.
On a flat surface, shake the sieves in one direction five times. Then rotate the separator box by 90 degrees. Repeat this process seven times, for a total of eight sets, or 40 shakes, rotating the box after each set of five shakes. There should be no vertical movement during shaking. See figure 2.
What to do with the outcome of the test
After the shaking process is complete, weigh the material in each sieve and in the bottom container. Record the outcomes in the fill-in sheet. Repeat this for the three samples along the feed fence. After weighing the materials, put them in piles as shown in Figure 1, to compare them visually. Also compare the weighing data. Count the total amount of material. Then divide each sieve by the total amount so that you create a ratio by
percentage. Between the three samples along the feed fence, the maximum deviation should be 5%.
The ration that you shake needs to be in a certain ratio, as follows:
|Top sieve||Middle sieve||Bottom sieve||Closed container|
|Corn silage1||Min. 3%||45% – 65%||30% – 40%||5%|
|Grass silage||10% – 20%||45% – 75%||20% – 30%||Max. 5%|
|TMR/PMR + conc.||6% – 10%||30% – 50%||30% – 50%||Max. 20%|
- Higher quantities of corn silage result in higher percentages in the middle sieve.
- When you serve concentrates separately (concentrate feeder) look at PMR + conc.
With this outcome, you can judge the mixing quality of the ration and whether it is necessary to make any changes.
Some changes that you might think of are:
- Add extra water to the ration if there are a lot of concentrates in the bottom container.
- Look at the sharpness of the knives in your mixer wagon or Lely Vector system if the mixing quality is poor.
- Extend or shorten the mixing time if mixing quality is bad, or if the mix is too short and mushy. Consider an in-between mixing time during loading of the mixer wagon or Lely Vector system to extend the mixing time.
- Evaluate the loading order: long before short and dry before wet is a rule of thumb for better mixing.
Bear in mind that if the outcome of the particle separator test is good, cows can still select if the total dry matter of the ration is higher than 40%.
Please contact your local Lely Center for more information, the instruction card and the fill-in sheet for the particle separator tool.
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