Irene Henriques, York University, Canada, UC Davis
L. J. Bees Butler, UC Davis,

Most research on bST adoption has been ex ante in nature. Exceptions include Stefanides and Tauer (1999) and Barham (1996), which are ex-post in nature (estimated using data when bST was commercially available). The purpose of our study is twofold. First, animal studies suggest that the use of bST requires more comprehensive diet formulation based upon detailed feed testing - however, none of the empirical research on bST adoption include feed management practices as an independent variable. We ask whether the adoption of certain feed management technologies is an important explanatory variable influencing the adoption of bST? Second, we examine the characteristics of dairy producers that have discontinued using bST. In other words, how do these producers differ from those that are currently adopting bST and are feed management practices (or the lack thereof) important explanatory variables. Data from over 400 California dairy producers were used to estimate the characteristics of bST adoption in 1997 and the characteristics of those dairy producers that have discontinued using bST. Our results show that, indeed, feed management practices (adoption of feed buffers and total mixed rations) are important indicators of whether producers will use and continue to use bST. Furthermore, adoption results are consistent with previous ex ante and ex post studies.

Bovine somatotropin (bST) is a large, naturally occurring bovine peptide hormone involved in growth regulation and mobilization of body energy stores. Although the exact mechanism by which bST increases milk yield is not fully understood, its impact on yields may be dramatic. A large rapidly growing body of experimental results suggests immediate responses of 10 to 20 percent increases in yield in dairy cows receiving bST (Cassell (1992)).

Prior to the introduction of bovine somatotropin (bST) in 1994, milk production in California had more than doubled from 1971 to 1991. According to Zepeda, Butler and Carter (1991), much of the increase in production was due to rising productivity per cow as a result of rapid adoption of improved management and production technologies. Since the introduction of bST, animal science studies have shown that the consistency of feeding and management practices has become even more important (Shaver (1998), Coppock (1992)). These studies suggest that the use of bST requires more comprehensive diet formulation based upon detailed feed testing. According to Coppock (1992), those dairy producers who have a nutrition program based upon continuous and comprehensive feed testing, with the intended nutrient profile confirmed in the final mixture, plus feeding systems, such as total mixed rations - which allow cows continuous access to feed - have a much greater probability of success when they adopt bST.

Using 1997 data of California dairy producers, the purpose of this study is to address the following questions:

1. Is the adoption of certain feed management technologies an important explanatory variable influencing the adoption of bST?
2. Of the dairy producers who no longer use bST but had adopted it in the past, were feed management technologies (or the lack thereof) an important explanatory variable?
3. Are the characteristics of the dairy producers who have never used bST but are considering using it in the future similar to those who have adopted bST in 1997?