Perennial Legume Pasture As a Component of Organic Dairy Systems.

In a 2009 Economic Research Service publication by McBride and Green, the milk production and feed costs of organic dairies were compared based on the amount of pasture fed. Dairies that used the most pasture had 25% lower feed costs but 30% lower milk production than dairies that used the least pasture. New Zealand research has demonstrated that milk production of cows fed the non-bloating perennial legume birdsfoot trefoil (BFT; Lotus corniculatus), which contains a low concentration of condensed tannin, is significantly higher than the production of cows fed perennial ryegrass (Lolium perenne). Birdsfoot trefoil-fed cows also have lower methane output, and nitrogen mineralization is slowed. Coupled with the fact that the nitrogen for BFT growth is generated by biological fixation, which allows the plant to use soil nitrogen or fix additional nitrogen as needed, the utilization of BFT pastures could improve both the economic and environmental sustainability of grazing-based organic dairies. Our previous research has demonstrated that BFT is persistent in the cool, dry climate of the northern Mountain West, while it is less persistent in warm, humid regions. Our current research, in partnership with a number of organic dairy producers, will examine the feasibility of using BFT as an alternative to grass pastures for organic dairy production in the northern Mountain West.