Effects of Herbage Allowance on Herbage and Dietary Attributes of Coastal Bermudagrass

The effects of four levels of continuous stocking rate on herbage allowance level (HAL, units of herbage DM/unit of grazer BW and growth, morphology and dietary attributes of Coastal bermudagrass (Cynodon dactylonL. pers) were evaluated. Single pastures were stocked to achieve mean herbage allowances of 8.9, 34.5, 80.7 and 148.3 kg DM/100 kg BW of cattle from June 1 through September 17. Daily net herbage growth rate decreased linearly (P< .01) with advancing date and was not affected by HAL. Quadratic interactions existed (P< .05) between HAL and date for the proportion of leaf in herbage and diet. The proportion of dietary leaf declined quadratically (P< .01) at each HAL with advancing date. Linear and quadratic interactions between HAL and date existed (P< .01) for the NDF content of herbage and dietary leaf. Dietary leaf NDF increased linearly (P< .01) with increased HAL at all dates. Within date and HAL, the NDF content of herbage leaf was similar to that of stem. Grazing selectivity for diet leaf of lower NDF content (diet leaf NDF/herbage leaf NDF) increased as HAL was reduced. Decreasing HAL via increasing grazing pressure reduced the mean age of the herbage mass by responses in the morphology and growth of the herbage and reduced the fraction of herbage mass prehensible by the animal.