Semi-Virtual Model Farmlets to Study Nutrients in Livestock Farms: Proposed Dairy System Case Study.

Efficient use of nutrients in livestock operations is necessary to minimize waste and environmental contamination. This requires optimisation of nutrient and crop husbandry on the field scale. It also requires effective livestock management and the efficient marriage of farm crop production and feeding practices. Studies of model dairy farms featuring innovative management systems, such as the DeMarke farm in The Netherlands, are logistically complex and expensive, and have not been attempted in Canada. This project, funded by AAFC, uses semi-virtual model farmlets to test novel dairy farm systems in three contrasting environmental and economic contexts across Canada: NFLD, with limited land and harsh summer climate; BC, with limited land and a mild climate; NS, with intermediate climate, more abundant land and greater use of grazing. The study will use miniaturized farm fields managed with actual and novel farming practices; the harvested crop samples from the farmlets will be chemically analyzed and subject to advanced feeding models (NRC Dairy, CNCPS, CPM Dairy, etc.) to predict feed supplementation, nutrient excretion, and milk yield. The modelled excretion data will inform nutrient managements on farmlet fields. For example, BC model farms are based on production of silage corn and perennial grass and will include conventional management, enhanced nutrient management, enhanced nutrient and crop management, and real-time enhanced management. Nitrate leaching and nitrous oxide emissions will be measured, while ammonia emissions will be predicted using ALFAM 2 model. Ultimately, the entire farms will be modelled using whole farm models like IFSM and HOLOS to account for losses at all farm stages. It is anticipated that this approach will be useful for other livestock sectors and subsectors like feeder pigs, poultry broilers, and beef cattle feedlot and cow-calf.