Does use of rbST increase mastitis rates in cows?
2. Are cases of mastitis more severe/less easy to control in cows treated with rbST compared to controls? 3. Does rbST use increase the amounts of drugs given to cattle to treat diseases? 4. Does increased drug use in dairy cattle exacerbate the problem of antibiotic resistance in pathogenic bacteria and/or residues in milk? Much of the data analysis that follows is based on the work of David Kronfeld, who has followed this issue very carefully in the U.S. and has published some major analyses of these data (Kronfeld, 1994, 1997). Does use of rbST increase mastitis rates in cows? Most of the evidence needed to answer this question has emerged since 1992. According to the U.S. Food and Drug Administration, which used data from eight Monsanto-sponsored trials in its decision in 1993 to approve Monsanto’s rbST product (POSILAC), the answer is yes. The data from these eight trials, which involved 487 cows, showed that during the period of rbST treatment, mastitis incidence increased by 76%
