Effluent properties and gas emissions from a conventional wintering area and an alternative stand-off pad providing outdoor exercise to dairy cows

Stand-off pads are uncovered outdoor yards built with absorbent materials, where cattle can be raised to minimize the environmental impact associated with nutrient runoff and gas emissions from manure management. Consequently, they emerge as a prospective alternative to traditional wintering pens, facilitating movement opportunities for dairy cows typically confined to tie-stalls. The objective of this study was to validate the potential of an improved stand-off pad concept (with sphagnum peat moss, woodchips and biochar) aerated with the exhaust air from the adjacent barn, in contrast to a conventional wintering pen, to provide outdoor exercise to dairy cows housed year-round in tie-stall barns Quebec, Canada. Both outdoor yards (28 m²) housed one Holstein dairy cow during 1.5 hr, twice daily (morning and afternoon), throughout two 9-week periods (summer and winter). Sampling of effluents and measurement of greenhouse gases from each area were performed on a weekly basis over the course of the study period for both seasons. Results showed that the stand-off pad was more efficient in removing biochemical oxygen demand, chemical oxygen demand, total nitrogen, suspended solids, and E. coli (32.9, 194.2, 19.8, and 24.3 mg L⁻¹, and 2.2 CFU (100 mL)⁻¹, respectively), relative to the wintering pen (95.3, 379.5, 54.2, and 43 mg L⁻¹, and 197 CFU (100 mL)⁻¹, respectively). Additionally, relative to the wintering pen, the stand-off pad media filter achieved a greater absorption capacity (water effluent volumes of 18.8 m³ and 25.3 m³ respectively). Aeration did not improve the removal of contaminants but resulted in lower nitrous oxide emissions compared to the wintering pen. A nitrogen balance was also calculated, obtaining 62 % recovery for Stand-off pen and 45 % for the winter pen. Improved stand-off pads can indeed provide a more sustainable and comfortable environment for dairy cows. By reducing mud and manure buildup, these pads help maintain cleaner and healthier conditions, which is beneficial for both the cows and the environment.