Rapid assessment of feed and manure nutrient management on confinement dairy farms

A basic function of dairy farming is to transform feed nutrients into milk to generate an economic return. As the price of feed grain escalates, and environmental concerns associated with animal agriculture heighten, many dairy producers seek new ways to track nutrient use on their farms. Relatively little information is available on feed and manure management under producer conditions. The present study provides an overview of an iterative process used to develop and apply techniques for rapid assessment of feed and manure management on confinement-based dairy farms in very different geographic settings. Information was collected on cow diets, milk production and manure management using rapid (2-3 h) survey techniques first on 41 dairy farms in Wisconsin, USA and then on two dairy farms in Shandong Province, China. In both locations, Holstein dairy cows (Bos taurus) transformed on average 22-30% of feed nitrogen (N) and phosphorus (P) into milk. These calculated feed N use (FNUE) and feed P use (FPUE) efficiencies corresponded well to published values, but were lower than FNUE and FPUE determined under experimental conditions. Average apparent feed N intake (range of 438-635 g cow(-1) d(-1)) were slightly higher than the calculated sum of N outputs in milk (98-145 g cow(-1) d(-1)) and manure (328-457 g cow(-1) d(-1)). Calculated manure N excretions corresponded well to literature estimates. Average manure collection efficiencies ranged from 56% to 100% in Wisconsin and 55 to 90% in Shandong. Relatively short, face-to-face interviews can provide accurate 'snap-shots' of overall feed and manure management practices on an array of confinement-based dairy farms in diverse geographic locations.