The aim of this study was to measure the effects of stage of maturity and level of nitrogen (N) fertilisation of Panicum maximum cv. Gatton on intake, ruminal fermentation and the partial digestibility of organic matter (OM) in sheep grazing the grass. More mature compared to younger pasture resulted in lower N, higher neutral detergent fibre (NDF) and acid detergent lignin (ADL) concentrations and lower OM digestibility. Nitrogen fertilisation increased the N concentration of the pasture, with no consistent effect on either NDF or ADL concentrations, but digestibility tended to decrease. Dry matter intake decreased with both increasing maturity and N fertilisation levels. Rumen pH levels increased with stage of maturity, with no effect from N fertilisation. Grazing of more mature pasture resulted in lower rumen ammonia nitrogen (NH3-N) and volatile fatty acid (VFA) concentrations and higher acetic:propionic acid ratios. Increased N fertilisation levels gave higher rumen NH3-N concentrations, with a tendency to increase VFA concentration and decrease acetic:propionic acid ratios. As the pasture progressed from the young to the mature stage, OM disappearance in the rumen decreased. Increasing levels of N fertilisation had the same effect during the full bloom stage. It was concluded that P. maximum cv. Gatton pasture would be of a better quality at a young stage of maturity as well as at a relatively low of N fertilisation during autumn.
An evaluation of Panicum maximum cv. Gatton at different stages of maturity and fertilised at different levels of nitrogen durin
Author: W.A. van Niekerk, A. Taute and R.J. Coertze
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