| Total nonstructural carbohydrate (TNC) concentrations
generally increase in forages during the day and decrease at night. The
objective of this study was to quantify the TNC concentrations in the upper
and lower parts of the grass canopy at the end of a light and subsequent
dark period and relate these changes in animal grazing behaviour and production
responses. Grass grown in controlled-environment chambers was cut after
a 15-h light and a subsequent 9-h dark period, and tillers were separated
into leaves and pseudostems. Leaves, but not pseudostems, demonstrated diurnal
fluctuation in TNC. Leaf TNC concentrations, after 15-h of light, were 1.6
times greater than those in leaves following the 9-h dark period. It is
suggested that animal production may benefit from afternoon vs morning turnout
onto fresh pastures because of the extra sugars in the leaves. |