INFLUENCEOFMATURITY ANDFREQUENCYOFHARVEST ON THE NUTRITIVE QUALITY OF COOL SEASON FORAGE LEGUMES

Eight cool season legumes of the genera Medicago, Trifolium, Ornithopus and Vicia which gave good forage yields in Northland were chosen for analysis of forage nutritive quality. Forage harvested on three dates from mid-winter to mid-spring showed a progressive decline in protein and digestibility, paralleled by a fall in the proportion of leaf tissue. A single mid-spring cut maximised yields, but reduced protein content and digestibility. Substantial species variations were apparent, with later flowering Medicago spp. and Trifolium spp. retaining quality longer than earlier flowering types. 0. sativus and V. dasycarpa also retained good protein content and digestibility. The level of some mineral nutrients (P, K, Na) also varied with maturity and between species, while others (Ca, Mg) remained relatively constant. The nutritive quality of most of these legumes would meet animal production requirements if grazed at two monthly intervals. However, if the legumes are conserved after six months growth, species variation in nutritive quality is likely to be more marked and some types would find definite preference, depending on the class of livestock consuming the forage.