Contribution of Stems and Leaves to the Composition and Nutrient Content of Irrigated Bromegrass at Different Stages of Development

Irrigated bromegrass (Bromus inermis Leyss.) at Swift Current, Saskatchewan, was sampled for 14 consecutive wk. Quantitative and qualitative measurements at each sampling included yield, crude protein, cell wall lignin, gross energy, and in vitro digestible energy content of leaves and stems. Dry matter yields increased steadily to 8,500 kg/ha at flowering. Proportion of leaves by weight decreased to about 40% at maturity. Crude protein content of leaves from the boot stage onward remained 10–12 percentage points higher than that of stems. Cell wall lignin content approached 75% in stems with advancing maturity, whereas in leaves it did not exceed 60%. Digestible energy content of leaves declined to 57% at maturity, and that of stems declined to 34%. For whole plant harvesting for hay there was a 2-wk period from headed out to mid-bloom where nutrient energy yields were nearly constant.