DIFFERENCES IN FEEDING PRACTICES ON ORGANIC AND CONVENTIONAL DAIRY FARMS – DATA FROM A FARM NETWORK

Summary

Organic and conventional feeding practices of dairy cattle differ due to specific regulations that are in place for organic farming. E.g., dairy cows must have access to pasture, and soybean extract, a very common concentrate in conventional dairy feeding, may not be fed. The joint project “Climate Effects and Sustainability of Agricultural Systems – Analyses in a Network of Pilot Farms” determined feeding practices and feed qualities on a total of 44 dairy farms (22 organic and conventional, each) in four German regions for 2008, 2009 and 2010. The average diets of the dairy cows differed considerably between organic and conventional dairy farms. Organic farms with a high percentage of hay in the diet were found in East and South Germany. The low percentage of concentrates in dairy rations is typical for the organic farms in the alpine region. In all regions the importance of grazing was significantly higher on the organic compared to conventional farms. Also, on conventional farms in the coastal region of North Germany grazing was of higher importance than in the other regions. Organic dairy cows received more fiber rich hay that produces relatively more CH4 and conventional dairy cows were fed more readily degradable concentrates that produce relatively less CH4. Hence, from the combination of diet and feed quality it can be expected that organic dairy cows produce slightly more CH4 from enteric fermentation per kg feed consumed (DM) than conventional dairy cows.
In summary, feedstuffs and their qualities were farm specific and should be considered in the calculation of methane emissions from enteric fermentation. Additionally, the differences in feeding regime have consequences for the primary energy use for feed production. These factors and must be considered in detail to conclude over greenhouse gas emissions from milk production on farm level.