The green biorefinery offers a way to produce protein-rich feed for monogastric livestock (poultry and pigs) from fiber-rich grassland forage. This protein-rich feed does not compete with human food production. Therefore, a new biorefinery plant was built and tested on a practical scale using silage made from clover grass and red clover as part of the EU project Farm4more (LIFE18CCM/IE/001195).
After biorefining, the fresh press juice was thickened after a short storage period for further use as feed for mongastrids and added to a compound feed, while the fresh press cake was ensiled again in round bales. Samples of silage, press juice, fresh press cake, and re-ensiled press cake were analyzed for nutrient composition, fermentation parameters, amino acids, and biogenic amines. Furthermore, the digestibility of silage and re-ensiled press cake in dairy cows tested .
We found that the pressed juice contained approximately 205 g/kg DM (dry matter) crude protein, more than 180 g/kg DM crude ash, and more than 130 g/kg DM volatile organic compounds, such as fermentation acids, ethanol, and ammonia. Furthermore, the pressed juice exhibited an unfavorable amino acid ratio for use as a monogastric feed (methionine and cysteine levels were low), and the content of biogenic amines was elevated compared to the original silage. The type of forage (clover grass or red clover) had little effect on the nutritional value of the pressed juice. Re-ensiling of the press cake was successful , as a sufficient reduction in pH and concentrations of lactic and acetic acid, as well as other volatile organic compounds, typical for silage were observed. The press cake had a crude protein content that was 26-36 g/kg DM lower and a metabolic energy content that was 0.77-1.12 MJ/kg DM lower than silage, with the differences being greater for red clover silage than for clover grass silage.
Pressed juice can be used as feed for monogastric animals, but its use is limited due to its low crude protein content compared to protein concentrates and its unfavorable amino acid profile. Press cake could be a suitable feed for ruminants , especially dry cows or heifers.
More detailed results of this experiment can be found in the journal article and in the conference reports of the 2023 conference on organic agriculture.
More information: Online Library
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