Dry matter yield, chemical composition and estimated extractable protein of legume and grass species during the spring growth.

Background: Knowledge of the variation of extractable protein amount in legumes and grasses as affected by harvest time is important for identifying optimal combinations to enable a high protein production in a biorefinery. The extractability of protein was estimated using the Cornell Net Carbohydrate and Protein System across six harvests during the spring growth.

Results: The estimated extractable protein [g kg dry matter (DM)] defined as the easily available fractions B +B was significantly higher in white clover and lucerne at all harvests while, if the more cell wall attached fraction B can be extracted, white clover had the highest extractable protein amongst all species. Total yield of B +B per ha was higher in white clover and red clover at the early growth while B +B +B was by far the highest for red clover through all harvests.

Conclusion: White clover could be a good candidate for protein production purpose in a biorefinery due to its high extractable protein content per kg DM. In order to maximise the protein production capacity, harvest should take place during early growth due to a decline in protein extractability with maturity. The final economy of the concept will depend on the value of the fibre after extraction of the protein. © 2017 Society of Chemical Industry.