Morning and afternoon sampling and herbage chemical composition of rotationally stocked elephant grass cv. Napier

Abstract

Nutrient intake by grazing animals depends on the amount of dry matter consumed and its chemical composition. Forage grasses produce assimilates during the day via photosynthesis to sustain live tissues, plant growth and organic reserves (Taiz and Zeiger 2013). In that context, herbage chemical composition may vary according to variations in the photosynthesis-respiration balance throughout the day. From dawn to dusk photosynthesis predominates and herbage dry matter content and concentration of soluble carbohydrates increase; the reverse happens from dusk to dawn. That could influence nutritive value and nutrient intake of grazing animals (Delagarde et al. 2000), since for a given bite volume the amount of herbage and its composition could vary depending on the time of the day. This phenomenon could have implications for rotationally managed pastures, with time of changing animals from one paddock to the other assuming greater importance. Against that background, the objective of this experiment was to evaluate dry matter (DM) content and the concentrations of soluble carbohydrates (SC), crude protein (CP), neutral (NDF) and acid (ADF) detergent fiber in herbage samples harvested during the morning and afternoon periods from rotationally stocked elephant grass (Pennisetum purpureum) cv. Napier.