Eleven years of organic dairy production in Denmark: herd health and production related to time of conversion and compared to conventional production

This paper focuses on the changes in production, herd health and veterinary treatments in Danish organic dairy herds over similar to11 years based on historic data from herds converted to organic milk production before 1990 (old organic herds) compared to herds converted in 1995 and 1999-2000 and herds that are still conventional. Herd size, milk production, the shape of the lactation curve, somatic cell counts and veterinary treatments for mastitis, retained placenta and ketosis were compared over time and between herd groups. The old organic herds differed from the other three herd groups by having lower milk production per cow, lower somatic cell counts and fewer treatments for mastitis. Herds converted in 1995 and 1990-2000 were comparable to the conventional herds before conversion for all analyzed parameters. However, herd size was larger than both the older organic herds and the conventional herds after conversion. Production was similar to2 kg energy corrected milk lower per cow per day than before conversion and compared to the conventional herds. In the herds converted in 1999-2000 little difference could be seen in relation to udder health after conversion when compared to conventional herds. The organic herds had fewer treatments for retained placenta and ketosis than the conventional herds. The shape of the lactation curves changed over the 11-year period with better persistency from day 60 to day 305 in all herd groups except for the old organic herds, which had the best persistency in 1990. (C) 2002 Published by Elsevier Science B.V.