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Farmdesk ration calculation - some changes

Jef Aernouts, Wim Govaerts

When we launched Farmdesk in 2019, one of our ambitions was to offer a user-friendly ration module to dairy farmers. And we believe we have succeeded in that.

In that reasoning, we chose to show only the necessary key figures to keep the overview. The 10 key figures that we have always used to date are, on the one hand, the calculated parameters intake, VEM, FOS, DVE and OEB and, on the other hand, the "hard" key figures crude protein, crude fiber, starch, sugar and fat.

We recently received constructive feedback from several livestock producers, for which we thank them. What came back frequently was the request to also include the key figures bypass starch and NDF. We like to listen to our users, and have decided internally to include these in the rationing from now on.

Below is more explanation of how the new key figures were chosen, and how they will be used in Farmdesk.

NDF and ADL in practice

Some will ask the question: why include additional parameters such as NDF and ADL to actually say the same thing as crude fibre? To do this, let us first explain NDF and ADL. NDF stands for Neutral Detergent Fibres, and includes the entire cell wall fraction. It is composed of:
  • A middle lamb - particularly contains pectins. Pectins are digestible in the rumen to propionic acid which after passage in the liver can give rise to glucogenic energy.
  • A primary cell wall - specifically contains cellulose and hemicellulose. Cellulose and hemicellulose are in turn largely converted in the rumen to acetic acid which is used as a building block for milk fat .
  • Eventually a secondary cell wall - contains particularly lignin (wood dust) and possibly cutin (cork dust). Lignin and cork dust are digestible in the rumen.
The ADL fraction (Acid Detergent Lignin) specifically designates the latter indigestible lignin fraction. There is a clear correlation between crude fiber and NDF. We also see a correlation between the digestibility of the NDF on the one hand and the ADL fraction on the other. Which makes sense, because with a percent high proportion of ADL, there is strong shedding of the crop which undermines digestibility. Too spacious a proportion of NDF in the ration can give rise to slow digestion rate, insufficient intake and reduced productivity. Supplementation with concentrates with low NDF is then desirable, for example wheat with 117 grams of NDF per kg of product. Sometimes the NDF fraction is further disturbed in its digestibility by a high proportion of ADL (lignin). This will further impair productivity and certainly requires supplementation with rapidly digestible concentrate with low NDF and ADL, for example beet molasses with 0 grams of ADL and an NDF of only 14 grams per kg of product. If the NDF value in the ration is too low, recovery activity may be undermined. Supplementation with NDF-rich roughage is then desirable. To maximize the effect, it is then best to choose roughage with a generous ADL/NDF ratio, for example rapeseed straw with NDF of 830 g/kg DM and an ADL/NDF of 12%.

NDF and ADL in Farmdesk

In the typical Farmdesk ration graph, we have replaced Crude Fiber with NDF. Given the correlation between the two, this in itself brings nothing new. The Crude Fiber value and norm, by the way, remain consultable via the Details button.

What is new is that we also show the ADL/NDF fraction . This value indicates what percentage of the total NDF consists of non-digestible ADL. As described above, this value provides additional supplement about the digestibility of cell walls.
The standards below have been implemented for Holstein cows:

  • NDF standard
    • 333 g/kg DM at start of lactation
    • 343 g/kg DM in the second half of lactation
  • ADL/NDF standard
    • 3% (where we use a fork of 1%-5%)


In the graph above, an example ration score with an overly high ADL/NDF fraction where the NDF standard does sit well. At too high ADL of 6% of all NDF, the digestibility of total NDF is also compromised. So we can assume that with a high ADL fraction within the total NDF , it is best to aim for a relatively low NDF that positions itself at the bottom of the green zone.

Bypass starch in practice

Starch is a cellcontent carbohydrate (unlike cell walls in NDF).

The unresistant starch fraction (which digests in the rumen) can serve as an energy source for the pens microbes (FOS) and/or can be converted in the rumen to propionic acid which, after passing through the liver, can give rise to glucogenic energy for the cow. Excessive unstable starch can give rise to strong lactic acid formation resulting in pens acidification .

The bypass starch fraction does not digest in the rumen, but goesonly in the small intestine to be able to be digested by pancreatic enzymes. Thus, it directly gives rise to glucose uptake from the intestine and glucogenic energy for the cow. If the starch is so resistant or excessively present in the small intestine, this can make the digestion here insufficient and this fraction gives rise to starch residues in the thick intestine. We then get unwanted bacterial growth here resulting in possible toxin production which can give rise to health problems such as colon inflammation, increased cell count and even increased risk of mastitis.

However, it is not all doom and gloom regarding resistant starch. A high-yielding starting cow benefits from getting enough resistant starch to stay out of negative energy balance. Problems with negative energy balance because of too tight a supply of resistant starch, can be solved by feeding corn or potatoes to new-calf cows. Potatoes have 627 grams of starch per kg DS, of which 276 grams are resistant. Corn meal has 640 grams of starch per kg, of which 210 grams is resistant.

Later in lactation the starch in the gut may get too much as the ample glucose in the blood may give rise to increased insulin levels in the cattle, which in turn may give rise to fatty and underproduction. Sometimes a recently ensiled mature cut corn gives rise to excess intestinal digestible starch. We then often see maize kernels in the manure. Soaking with water before feeding can bring relief, but often this also improves on its own if the corn remains ensiled longer, with the soaking process taking place in the silage itself over time.

Bypass Starch in Farmdesk

In the typical Farmdesk ration graph, we have displayed bypass starch as additional information at the top of the starch graph. The standards below have been implemented for Holstein cows:
  • Resistant starch
    • 50 g/kg DM at start of lactation
    • 30 g/kg DM middle lactation
    • 10 g/kg DM end lactation
  • Starch
    • ~250 g/kg DM at start lactation
    • .
    • After 100 days of lactation gradual decrease to ~100 g/kg DM at 360 days into lactation

In the graph above, an example ration score with an excessively high BZET fraction where the ZET value is tight. If the total starch standard was not met, excess resistant starch is of less importance. In fact, ample resistant starch is a blessing in starch tightness.

On the other hand, however, it is important to be sure to guard against excessive levels of total starch when there is an excess of bypass starch. With ample levels of bypass starch, a longer storage time can be a boon. The addition of water to the ration can also accelerate digestibility, with the greatest effect being obtained if soaking is done half or full day in advance.

About the authors

  • Jef Aernouts

    Jef Aernouts is the manager of Farmdesk. With experience as a product developer, a PhD in Physics and a farming background, he is the connecting bridge between digital innovation and on-farm practice.

  • Wim Govaerts

    After completing his Master's degree in Agricultural Sciences, Wim Govaerts founded a consultancy firm specializing in technical and business-economic advice for companies involved in milk-producing ruminants. Within Farmdesk, alongside his role on the board, he serves as an agricultural expert, combining extensive theoretical knowledge with practical experience.