Case Study: Documenting grass growth and productivity in a grass-based organic dairy in Oregon

Managing pastures on grazing dairies is a continuous challenge because pasture quality, quantity, and growth rate are changing daily. The objectives of this study were to document weekly pasture growth, forage quality, and performance to understand how to use this information to make management decisions on US dairies. One organic grazing dairy was studied for 3 consecutive years. Pastures were measured and mapped, and total standing DM was estimated weekly in all 22 pastures using a calibrated rising plate meter. Weekly grazing wedges were developed and were used to make grazing decisions that week. Paddocks grazed and residual pasture covers were recorded daily. Paddock grazing and residual heights were also included in the electronic recordkeeping. Dry matter yields ranged from 11,277 to 22,346 kg/ha per year and averaged 15,887 ± 1,919, 17,848 ± 1,966 and 17,956 ± 2,014 for each consecutive year. Daily growth rates ranged from 18 to 100 kg/ha per day throughout the season and averaged as high as 56 ± 20.3 kg/ha per day in yr 3. Pasture quality and productivity in Oregon is comparable to some of the most productive dairy pasture systems reported from around the world.