Comment: Economic Impacts Associated with Recombinant Bovine Somatotropin (rBST) Use

Abstract

The article "Economic Impacts Associated with Recombinant Bovine Somatotropin (rBST) Use," which appeared in AgBioForum 3(2&3), merits somewhat closer scrutiny. The article was based on a pair of regression models which Ott and Rendleman (2000) had developed for herd milk production and for herd "nonmilk productivity." These regression models are quite similar to a series of models that Ott, Wells, and Wagner (1999) and Ott and Novak (2001) had created to examine economic losses associated with Johne's disease and with bulk-tank somatic cell counts, respectively. Either Ott and Novak (2001) need to retract the square root of the percent of rBST use as an explanatory variable for milk production, or Ott and Rendleman (2000) ought to reconsider the quadratic expression for the percent of rBST use in their model for milk production. Both models lead to very different conclusions about the relationship between rBST use and milk production, and both cannot be correct.