Fresh grass feeding for organic dairy cattle

Fresh grass, taken directly from the field and served to the cows in the parlour, allows you to increase the proportion of grass feed in the cows' ration and save on purchased protein feed.

By Irene Fisker

Disclaimer: Please note that this text has been translated from Danish to English automatically and may contain errors.

Higher AAT value in fresh grass

The advantage of fresh grass over silage is that the protein in the fresh grass is intact and therefore the AAT value (the amount of amino acids absorbed in the gut) is higher. During the ensiling process, some of the protein is broken down into peptides, amino acids and ammonium.

The crude protein content may also be slightly higher in fresh grass than in silage because fresh grass is typically cut more frequently than silage. These two factors mean that it is possible to save on purchased protein feed - in some cases, for example, 1 kg of protein feed per cow can be replaced by grain.

Photo: Cows have a good appetite for fresh grass.

Fresh grass in the barn requires good pasture management

With planning and a good overview of grass development, you can ensure that there are always areas with good quality grass to harvest from. This can be compared to grazing management, where cows have to go out to a new patch every day.

However, grass quality will vary from day to day, even with good pasture management. Furthermore, on farms that feed grass separately, there will be a difference in how much grass and how much forage each cow eats. Both of these can be a challenge in terms of how high a yield can be achieved.

Fresh grass must be collected every day. This typically takes 1-2 hours a day.

The feed ration can contain more grass when feeding fresh grass

The feed ration can contain large amounts of fresh grass because organic dairy farmers use the fresh grass as a supplement to the grass that the cows themselves eat when grazing. For example, on one farm in 2020, a total intake of 14 kg dry matter of fresh stable grass and pasture grass per cow per day was recorded on average for the entire grazing season (Munk, 2020).

The season for stall feeding is long. Many cattle farmers who use fresh grass in the parlour for dairy cows begin in May and end at the end of October. In mild autumns, when the grass continues to grow, fresh grass may still be on the menu in November.

Harvesting and feeding technique

To harvest the grass, you can use the specialised MaksiGrass machine or the front mower and collector wagon. The MaksiGrass harvests the grass gently and without shredding. The front mower and collector wagon system has a larger capacity and can be a good solution for herds with many cows.

Separate feeding of the grass is most common and, not surprisingly, experience shows that the cows like the fresh grass. However, the other feed is eaten in parallel, although as mentioned, we don't know how the individual cow composes its feed ration.

Mixing the fresh grass with the other feed can be done in a mixer wagon. Here you need to take into account that the fresh grass takes up a lot of space and that there is a greater risk of heat build-up when the grass is shredded. It is therefore particularly important to clean the feed table carefully.

Photo: The fresh grass can be mixed with other stable feed.

3-8 kg dry matter fresh grass per cow per day

Experience from 2022-2023, when the Innovation Centre for Organic Agriculture followed 11 dairy farms, shows that 2-12 kg dry matter of fresh grass was used per cow per day, but most often 3-8 kg.

The dry matter percentage in the grass varied between 12 and 24% and this variation should be taken into account when weighing the daily amount for the cows. Experience shows that the cows have the same appetite for fresh grass regardless of whether it is wet or dry.

Higher digestibility in fresh grass

The digestibility of the fresh grass from the farms in the project is shown in Figure 1. For comparison, national averages for the digestibility of organic clover grass silage for the years in question have been added.

Figure 1. Digestibility of fresh grass from organic and conventional farms (one colour per farm) in the project "Barn feeding with fresh grass" compared to the average digestibility of organic clover grass silage nationwide (Thøgersen & Kjeldsen, 2024).

There is great variation, but digestibility has generally been higher in the fresh stable grass than we typically see in clover grass silage.

The digestibility of the grass is affected by several factors, including the temperature during the growing season. High temperatures increase the lignin content of the grass, which decreases digestibility. In 2022, there was a hot period in late July and August, which also meant that the cows had less appetite for the fresh grass at that time.

Higher crude protein content in fresh grass

The crude protein content of grass generally increases during the season, and this was also the case in the fresh grass on the 11 farms, see figure 2. The figures reflect, among other things, an increasing proportion of clover, which on some farms reached 65-70% in the autumn. Samples with particularly low protein values consisted of crops without clover, such as green barley or ryegrass. In general, the crude protein content was higher in the fresh grass than in organic clover grass silage.

Figure 2. Crude protein content in fresh grass from organic and conventional farms (one colour per farm) in the project "Farm feeding with fresh grass" compared to the average crude protein content in organic clover grass silage nationwide (Thøgersen & Kjeldsen, 2024)

Trial results from Ireland and the UK

In Denmark, there is a growing interest in fresh barn grass, but so far most trial results come from Ireland and the UK. Milk production there is traditionally based on large amounts of grazing, but the desire to cover more distant areas and extend the season has led larger farms in particular to look at fresh grass feeding.

Trials from Ireland and the UK show that you can achieve at least the same milk production with fresh grass compared to grazing or grass silage, but often at a lower yield level than in Denmark. A Northern Ireland trial compared the production of cows fed either fresh grass or grass silage. The cows fed fresh grass had the highest ECM yield, see table 1.

Table 1. Comparison of feeding fresh barn grass and grass silage for a period of 22 weeks. Values with different letters are significantly different. (McDonnell et al., 2019).

	Fresh stable grass	Silage
Roughage intake, kg DM/day	12,^1b	11.^6ab
Concentrate intake, kg DM/day	6,37	6,37
ECM yield, kg/day	36,^7c	34,^5b

In another Northern Ireland trial, fresh grass in the barn also resulted in a higher milk yield than silage, even though the grass was harvested at the same stage of development. However, the fact that there were challenges in making successful silage in the summer was a factor here. When forage intake decreases, milk yield will suffer (AFBI, 2022).

In a trial in Scotland, supplementing with fresh grass in the parlour made no difference to milk yield. Cows were fed either a basic mixture (TMR) of grass silage, maize silage and concentrate or the same basic mixture supplemented with fresh grass in the parlour. The fresh grass made up about a third of the feed. The cows produced 36kg of milk per day during the trial period (Cameron et al., 2018).

References

AFBI, 2022, Zero-grazed grass, or grass silage produced from herbage at the same growth stage, for indoor feeding over the summer? Zero-grazed grass, or grass silage produced from herbage at the same growth stage, for indoor feeding over the summer? | Agri-Food and Biosciences Institute (afbini.gov.uk)
Cameron et al, 2018. A comparison of milk yields and methane production from three contrasting high.yielding dairy cattle feeding regimes: Cut-and-carry, partial grazing and total mixed ration. Grass and Forage Science/Volume 73, Issue 3/ p. 789-797.
McConnell, D., Scoley, G., Earle, E., Gordon, A. & C. Ferris, 2019. EuroDairy Webinar: Zero-grazing for feeding home-grown forages. AFBI, Northern Ireland. EuroDairy webinar: Zero grazing for feeding home grown forage - YouTube
Munk, A., 2020. Project Grass Milk - Annual Report 2020 - Farm A
Thøgersen, R., & A.M. Kjeldsen, 2024. Roughage 2022 and Roughage 2023 - LandbrugsInfo