Evaluation of temporal nutrient dynamics in pasture-based beef production systems

摘要

Achieving optimal mineral nutrition and animal performance in pasture-based livestock systems requires maintaining adequate mineral concentrations in plant tissue and supplements. Numerous factors cause variation in pasture-herbage mineral concentration. The objective of this study was to determine how herbage mineral concentrations vary between months throughout the growing season and to determine the relationships between mineral concentrations and environmental variables. Twelve sets of cool-season paddocks stocked with 7 or 8 beef cow-calf pairs were evaluated during a 4-year experiment in Virginia, USA. Pasture herbage was harvested once per month from April to October and analysed for mineral concentration. Herbage tissue mineral concentrations fluctuated throughout each growing season, with lowest average concentrations in July and August. A multivariate technique, redundancy analysis (RDA), was employed to determine the relationship between herbage nutrient concentrations and environmentalvariables. Soil moisture appears to be well related to variation in the concentration of many nutrients. A better understanding these relationships may lead to predictive modeling of pasture herbage nutrient concentrations for periods of abnormal weatherand allow for the adjustment of mineral supplements to optimize animal performance.