Nutrient use efficiencies, losses, and abatement strategies for peri-urban dairy production systems

Manure management is an important aspect of urban livestock production that has a profound impact on metropolitan living. Data were collected from 28 dairy farms in peri-urban Beijing and analysed to determine farm nitrogen and phosphorus flows and costs associated with various manure management options to reduce nutrient losses. Dairy production in peri-urban Beijing was characterized by its use of high protein diets (16.3-17.0% crude protein), high reliance on imported feeds (92-98%), and low manure recycling (3.0-10.8%). Farms of 900-2000 cattle showed lower use efficiencies than farms of <900 cattle. Costs of manure handling ranged from 0.1 to 1.0 Yuan kg^-1 milk. Among various manure treatment options, biogas digesters with aerobic lagoons had the lowest N losses and costs, justifying their investments. In conclusion, peri-urban dairy production systems were contrasting with traditional systems and within their own systems in nutrient use efficiency and losses, which was mainly decided by their farm size. To improve the nutrient use efficiencies and reduce losses, farmers and managers of peri-urban dairy production system should have a full awareness of different feed intake and manure management.