Long-term low-protein feeding of dairy cows

The feed track is demonstrably very effective and can be used immediately to reduce ammonia and methane. In recent years, however, the crude protein (RE) of dairy cattle rations has risen instead of falling, so a change is needed. This project aims to show the effect of long-term feeding of a low protein ration on the total ammonia emission, methane emission and the parameters regarding health, metabolism and milk production of the cow.

The target for dairy farming is to achieve tens of percent reductions in both ammonia (NH3) and methane (CH4) by 2030. For a significant reduction in NH3 emissions in the short term, the way forward (among other possible measures) seems to be to reduce the raw protein (RE) content of the ration, resulting in lower NH3 emissions from stables as well as from the use of the slurry is realized. Under the guise of what doesn't go in, it won't come out either, so a significant reduction in NH3 emissions can be achieved. The principle applies to any form of farm management or food production system. The RE-reducing measures may also achieve a reduction of CH4 emissions, even if that may only be part of the target for CH4 reduction.

Effects on health and production

In practice, there is still a fear of feeding drastically less RE due to possible effects on the production and health of the dairy cow. Moreover, with the current management, it can be difficult to achieve such a low RE ration. A barrier to lowering the RE content in rations is, among other things, a lack of knowledge, in particular knowledge about the possible long-term effects. The feed supplying sector itself recognizes the importance of investigating this in detail under controlled conditions. In the PPS Feed4Foodure-III, an animal trial has therefore started for a long period in which different contrasting RE levels are compared with each other (with a target of 16.0% RE in the ration as a control treatment, which is close to current practice, and targets of 13.3 and 14.7% RE as NH3 lowering treatments). This gives an expected reduction of NH3 compared to current practice of more than 15% (assuming a reduction from 165 to 150 g RE/kg DM), depending on the effect on N utilization by the dairy cow. This research, carried out by Wageningen University and Research, is necessary to be able to make a principled point about whether or not it is possible to use low RE rations on a permanent basis.

What research do we conduct?

This project, part of Feed4Foodure-III, contributes to a reduction of NH3 emissions in particular, but possibly also CH4 emissions, by feeding a low protein level in the ration of dairy cattle.

The aim of this multi-year project is to investigate the effect of long-term feeding at a low protein level in the ration (during 2 lactations, comparing rations with 13.3 vs 14.7 vs 16.0 % crude protein level). The aim is to investigate the effect on cow performance, metabolism and health of lactating dairy cows. For cow performance, we look at milk production, milk composition and feed intake. In addition, the direct gas emissions by the cow are measured (CH4, but also carbon dioxide) and we calculate the TAN excretion, as the main driver for NH3 emission.

In the current experiment, it was decided in consultation with the VDN (Association of the Animal Feed Industry of the Netherlands) to reduce the protein in the concentrate, which is also the most directly applicable. It was therefore decided to replace the protein in the control treatment with a balanced combination of starch and fibre. The methane emission will increase slightly at ration level due to the use of the fiber (in g CH4 /kg DM ration), however we expect a decrease in feed intake with low protein rations, so that the CH4 emission per cow is expected to remain the same or decrease .

At the innovation center Dairy Campus, part of Wageningen Livestock Research, an experiment is being carried out with 60 dairy cows at the start, in which the effect of a substantial reduction in the protein level in the ration on the performance and the metabolism and health of the cows.