Refining proteins from green crops for high quality feed products for monogastricanimals and dairy cows

Summary

Green biorefinery concepts have the potential to become a suitable solution for production of organic protein-rich feeds from green crops. Different green crops such as alfalfa, red clover and clover grasses are studied as possible feedstocks for the development of an organic biorefinery system with refined proteins, ensiled press cake to be used as cattle feed and residual juice with potentials for fermentation of amino acids, lactic acid or other uses. A process was developed by which screw pressed juice from the freshly harvested crop was used for lactic acid fermentation to decrease the pH and precipitate proteins. These refined proteins have a favourable amino acid content and are comparable with soy proteins, especially for poultry where methionine is a limiting amino acid. For production of experimental feed for different animal trials, a demo-scale set up was made for a continuous refining process, which included harvesting and processing of 400 tons clover grass. The clover grass was processed into a protein concentrate, a fiber-rich press cake, and a residual stream of soluble nutrients. The protein-concentrate was used in experimental feed formulations for egg-laying hens, broilers and pigs. The fiber-rich press cake was ensiled without additives, and used as feed for dairy cows. The novel protein refining technique using lactic acid fermentation showed robust results in large scale. Furthermore, the feed trials in mono-gastric animals (poultry and pigs) show promising results although the digestibility with increasing amount of green proteins show a decreasing trend. In addition, the ensiled press residues surprisingly resulted in a 5-10% increase in milk production compared with a traditional silage. Further improvements of the technology is expected to lead to feed products with higher digestibility as well as protein products for human consumption.