FEEDING VALUE OF BARLEY PLANTS AS RELATED TO STAGE OF MATURITY .1. MORPHOLOGICAL AND CHEMICAL-COMPOSITION AND IN-VITRO DIGESTIBILITY

A field study was conducted to determine the effects of stage of maturity on the yield, morphological composition and nutritive value of whole barley plants and their ear, internodial leaf blade, leaf sheath and stem fractions in order to determine an optimum stage of maturity to harvest. Organic matter digestibility and crude protein content decreased rapidly until grain filling at maturity code 55 (range of study, 2-digit codes 37 to 91) and then remained fairly constant. The yield of digestible organic matter increased with increasing stage of maturity (2nd degree polynomial function, P < 0.001). The study at three stages of maturity (code 83, 86 and 91) showed an increase in the ear fraction (48 to 57% plant dry matter, DM) and a decrease in plant remainder fraction (whole plant without ear, NOEAR) (52 to 43%) due to maturation. However, within NOEAR the leaf sheath fraction remained unchanged and both the leaf blade and stem fractions decreased. Generally, the highest nutritive value was measured for leaf blade and sheath in the uppermost internode, but for stem in either the upper most internode or lowest internode. The most distinct maturation effects were observed in the upper leaf blades. Nutrient translocation in context with changes in internodial nutrient concentration during maturation is discussed. The present results indicate, that whole-crop barley should be harvested at yellow ripeness (code 98).