Factors causing a higher level of liver abscesses in organic compared with conventional dairy herds

Summary

A data analysis based on the Danish Cattle Data Base shows that organic Holstein-Friesian cows have significantly higher frequencies of liver abscesses (LA) than conventional Holstein-Friesian cows (8% versus 5%). Based on a questionnaire among 91 organic dairy herds, a statistical analysis was made in order to identify which feeding and management factors that were related to the level of LA in the herds. Compared with conventional herds, the feed ration in organic herds had a lower energy and fatty acid level and a higher starch level. During summer season the organic herds had a lower level of digestible cell walls in the ration. Organic herds with a higher grazing level had a higher level of LA (P=0.012). Increasing levels of grain also tended to increase the level of LA. A herd-based analysis (644 herds) showed that lower minimum fat percentage and a higher variation in both fat and protein percentage corresponded with higher levels of LA. Organic herds generally had a 0.1 unit lower fat percentage. The results indicate that organic dairy cows, compared with conventional dairy cows, are more exposed to rumen acidosis and liver abscesses due to higher starch levels and unbalanced feeding strategies in particular during grazing.