Investigations on crude protein and amino acids in organically produced field pea (Pisum sativum L.) varieties

Summary

The content of essential amino acids in grain legumes is of special interest for monogastric animal feeding in organic farming. Therefore, we investigated the influence of variety on the contents of crude protein (CP) and amino acids (AA) as well as the relation between CP and AA in field peas.
Samples of 73 peas of 5 varieties (Alvesta, Auckland, KWS La Manscha, Navarro, Salamanca) were collected from field trials of organically managed experimental sites in Germany in 2011 - 2013. The contents of CP and AA were analyzed with NIRS. Pearson correlation analyses and mixed procedures were conducted in SAS 9.4.
Variety affected CP and AA in peas. Alvesta had the lowest content of CP (21%) and almost all AA per kg dry matter (p < 0.001). KWS La Manscha had the highest content of CP (23%) and all AA per kg dry matter (p < 0.001). However, KWS La Manscha had the lowest amount of total AA and each AA except arginine per 100g CP. There was a high negative relationship between CP and most of the AA in the CP of field peas (r < -0.63***). Only arginine was positively correlated with CP (r=0.61***), while histidine and leucine were not related with CP content. Tryptophan and the non-essential AA glutamic acid were less strongly negatively correlated with CP (r=-0.49***). The results indicate that higher CP contents could lead to more non-protein-nitrogen and an altered relation between AA. Thus, attention should be paid to amino acids rather than on CP in pea varieties used as feedstuffs.