Chemical composition, metabolizable energy and digestibility in pea seeds of differing testa and flower colors

Abstract

Chemical composition, tannin content, metabolizable energy, organic matter digestibility and their relations with gas production were assessed in pea seeds of differing testa and flower color in 2003 and 2004. The pea genotypes were classified in five testa colors (white, light green, dark green, dark green-brown and brown-black) or in two flower colors (white and purple). Wide variation existed in the chemical composition of the investigated individual pea genotypes between testa color or flower color groups. Crude protein content for pea seed samples varied from 192.3 to 262.1 g kg-1 with average N-free extract of 667.4 g kg-1, crude fiber of 65.1 g kg-1 and ether extract of 21.4 g kg-1. In general, crude protein content was higher in dark green-brown and dark brown-black seeded and in purple flowered genotypes. Dark testa colored pea genotypes had higher tannin content in both years; however this variation was not statistically significant. Purple flowered genotypes had significantly higher tannin content than the white flowered genotypes. White and green seeded peas with white flowers had consistently higher metabolizable energy than dark brown or black seeds with purple flowers, with an average of 12.6 MJ/kg DM for white seeds and 11.3 MJ/kg DM for dark brown black seeds. Organic matter digestibility showed a similar pattern to metabolizable energy. Gas production profiles showed variations in both rate and extent of gas production among the pea groups. Gas production from white and green seeded or white flowered genotypes was always higher than those of dark seeded or purple flowered genotypes. The correlation coefficients between tannin content and metabolizable energy, organic matter digestibility and gas production were weak and mostly non-significant.