Agronomic factors affecting yield and quality of extractable leaf protein 1 concentrate (LPC) in forage crops

Summary

The study aims to find the optimal cutting strategy and forage plant species for organic production of leaf 11 protein concentrate (LPC) and to investigate if sulfur fertilization have a positive effect on the content of the 12 sulfur containing amino acids cystine and methionine. The protein recovery in green juice and amino acid 13 composition of the proteins were measured for 23 common and alternative forage species grown in an 14 organic cropping trial. Total protein yield in green juice was measured for three different cutting strategies (2, 15 3 and 4 cuts per season) in three different forage species mixtures. The forage species mixtures were given 16 three levels of sulfur fertilization (0, 30 and 60 kg S ha-1). Results indicated that the economic optimum 17 cutting strategy was 3 cuts per season (7 weeks between cuts) as this yielded same total protein yield as a 18 more frequent cutting strategy. The highest protein recovery was found among plant species with high 19 protein content and low dry matter content. The tested plants species from the Brassicaceae group all had 20 high protein recovery, whereas the grasses generally had low protein recovery. Within the leguminous 21 species Anthyllis vulneraria, Trifolium repens and Vicia villosa all had the highest protein recovery. The 22 amino acid profile in the green juice differed between species, harvest dates and sulfur fertilization regimes, 23 however the differences were minor. The most determine factor for the protein quality was the plant species.