Opened grass as a sustainable alternative in dairy cattle rations

Grass refining can contribute to more sustainable dairy farming by creating a higher nutritional value from a hectare of grassland and by reducing emissions from cows. Grassa has developed a technology that allows the cow to make more efficient use of the nutrients in grass. In addition, the nutrients that the cow does not or poorly use are converted into food instead of manure.

Grass is the most available and perhaps also the most underestimated crop in the Netherlands. It contains an enormous amount of richness and can yield 2.5x more protein per hectare than, for example, soy. At the moment it can only be used by ruminants, mainly dairy cattle, which are capable of making food suitable for humans. However, the cow is not very efficient in using all the wealth contained in grass, because approximately 70% of the nutrients are released unused via manure, urine and emissions.

What is Opened Grass?

Opened grass is created from the first pass of the Grassa process. Freshly cut grass is pulled apart and pressed. The cell contents, containing the soluble nutrients (most unstable proteins, sugars and minerals), are removed with the grass juice. What remains is opened grass. The processed grass still contains sufficient nutrients that are easily accessible and easily digestible in the rumen and intestine of the cow.

The Grassa process ensures that the NDF digestibility increases and that proteins in the digested grass become more resistant. The cows can use these resistant proteins directly for the production of milk and meat. As a result, there are much fewer losses. For example, the emission of nitrogen (N) and phosphate (P) can be reduced by no less than 30%. The emission of methane (CH4) is reduced by 10 to 15%.

The juice that is pressed from the grass then yields a protein concentrate, prebiotic sugar concentrate and vegetable fertilizer. These ensure that we get 1.5 to 2x more nutritional value from the same hectare of grassland.

Why a follow-up study?

Over the years, various studies have looked at the usability of opened grass. The first trials were already carried out on the Dairy Campus in 2015, in 2018 at the WUR agro-innovation center De Marke and in 2020 extensive studies were carried out in collaboration with the Biorefinery Glass project in Ireland. This has provided many valuable insights. In the tested rations, opened grass reduced the proportion of raw protein in the ration, without causing a negative impact on milk yield and composition.

However, these rations were not always representative for Dutch dairy farming or the duration of the trial was too short to be decisive. That is why it has been decided to carry out a trial in collaboration with the Dairy Campus Innovation Fund and Mengvoederbedrijf (Compound feed company) Fransen-Gerrits. At Dairy Campus, we will work with common Dutch rations to show what the added value of opened grass can be for Dutch dairy farming.

Results of previous studies

Opened grass has shown in various tests that it increases both nitrogen and phosphate efficiency. For example, in the trial in Ireland a nitrogen efficiency of 33% was achieved, where the control group showed 27.6%. For phosphate, the group with refined grass achieved an efficiency of 46% compared to 27.4% in the control group. Milk yield is lower in Irish conditions than in the Netherlands, which is why it is important to find out whether we can achieve the same results in a Dutch ration.

Despite the fact that opened grass has a high proportion of NDF, in vitro studies have shown that it contributes to a reduction of methane formation in the rumen. A rumen mimic system (RUSITEC) was used for the study. The rations used in Ireland showed a 13% reduction in the use of opened grass. During the trial on the Dairy Campus, we therefore also measure the methane emission of the cows by means of the GreenFeed system and we are further investigating how we can explain these results.

In short, many valuable insights have been gained in recent years about the usefulness of opened grass for dairy farming. However, there are still many unanswered questions about the effect of opened grass in the ration and how the digestion of opened grass works exactly. It is certain that grass has much more to offer than is currently known. We expect to have the first results of the ongoing studies in early 2023.