Nutritive value for ruminants of two herbaceous South American native legumes: Adesmia bicolor and Adesmia macrostachya

Abstract

Chemical composition, in vitro fermentation and in situ degradability of the native South American legumes Adesmia bicolor and A. macrostachya were studied at vegetative (VG), flowering (FW) and seeding (SD) stages, and compared with those of alfalfa at 10% flowering (AL) in two separate studies. In A. bicolor, crude protein (CP) content was highest for FW, and FW and SD showed higher values than did AL (P < 0.05). At all stages, A. bicolor showed a lower content of neutral detergent fibre and acid detergent fibre than did AL (P < 0.05). The maximum gas production (Coefficient b) was highest for FW, and no differences were recorded between SD and AL, the lowest value being for VG (P < 0.05). The effective dry matter degradability was higher for FW and VG than for SD and AL (P < 0.05), whereas effective CP degradability tended (P = 0.077) to be higher for FW than for the other stages of A. bicolor, but no differences between FW and AL were detected. A. macrostachya had lower CP content (P < 0.001), but its VG and FW stages also had lower proportions of neutral detergent fibre, acid detergent fibre and acid detergent lignin (P < 0.01) than did AL. Chemical and fermentation parameters were affected by maturity of A. macrostachya. The effective dry matter degradability was higher for VG and FW than for SD and AL (P < 0.001), but no differences were apparent on the effective CP degradability. A. bicolor showed a high nutritive value, which was even higher than that of AL, and the maturity stage of this species did not markedly affect its nutritive value, whereas the nutritive value of A. macrostachya reduced as it matured.