Dale E. Bauman, Ph.D.
Liberty Hyde Bailey Professor, Department of Animal Science,
NYS College of Agriculture and Life Sciences, Cornell
University
Hollis N. Erb, DVM, Ph.D.
Professor of Epidemiology, Department of Clinical Sciences,
NYS College of Veterinary Medicine, Cornell University
David M. Galton, Ph.D.
Associate Professor of Dairy Management, Department of Animal
Science, NYS College of Agriculture and Life Sciences,
Cornell University
Philip M. Sears, DVM, Ph.D.
Associate Professor, NYS College of Veterinary Medicine and
Director, Quality Milk Promotion Services, NYS Mastitis
Control Program, Cornell University
The recent claims by M. Hansen (Consumer Policy Institute)
about bovine somatotropin (bST) causing catastrophic increases in
mastitis in Cornell studies are inaccurate. They simply represent
another case of misinformation where Hansen has told only part of
the story. Mastitis-related variables were not used in animal
assignment to treatment groups and in the Cornell studies Hansen
cited, animals assigned to the bST treatment group by chance had a
higher mastitis incidence prior to the start of treatment. Hansen
simply computed a numerical value of mastitis incidence in the
treatment period and failed to follow appropriate epidemiological
and statistical procedures to account for pretreatment differences.
Others of our published studies have by chance, had a higher
incidence of mastitis during the pretreatment and treatment period
for cows assigned to the control group. It would be equally
inappropriate had Hansen selectively chosen these studies, ignored
pretreatment status, and concluded that bST treatment cures
mastitis. Such a mistake is a serious oversight for anyone with
adequate scientific training.
Susceptibility to mastitis is related to many factors,
especially environmental conditions and milking management
practices. Mastitis depresses subsequent milk yield and this
reduced milk yield is a major component of the total cost of
mastitis. To properly evaluate effects of technologies on mastitis
requires both large numbers of animals studied under a range of
environmental and management conditions and application of
appropriate statistical methodologies. A number of reports have
summarized large data sets and evaluated the impact of somatotropin
on mastitis-related variables in lactating cows. Data from Cornell
full lactation studies and field studies have been components of
several of these including those by FDA and the European
Communities CVMP. FDA summarized six pivotal studies and by
chance, most of these had a higher incidence of mastitis in the
bST-group prior to initiation of treatment. Using a conservative
statistical approach they found that bST caused a small numerical
increase in mastitis (3). At the bST/Mastitis public hearing, FDA
and the Expert Advisory Committee considered these results and data
presented by others and concluded affects were of no biological
significance because they were inconsequential relative to the
major causes of mastitis. In the first instance, typically 30 to
50% of mastitis cases occur in the first 60 days postpartum - a
period when bST is not even used. Secondly, they pointed out that
the impact of bST was minor as a cause of mastitis - for example,
the effect of season was 9.8-fold greater, the effect of parity was
6.5-fold greater, the effect of herd was 4.8-fold greater, and the
effect of stage of lactation was 7.1-fold greater, to name just a
few factors.
Other studies have summarized even larger sets of data and in
all cases these evaluations have concluded that bST does not affect
mastitis or mastitis-related variables (1, 2, 4, 5, 6, 7, 8, 9, 10,
11, 12, 13). These summaries demonstrated that somatic cell
counts and incidence of mastitis were related to many herd factors,
especially environment and milking management practices, and these
effects were equally evident in both control and bST-treated
groups. The White et al. (12) study, which includes Cornell data,
represents the most extensive summary to date. First presented as
an invited paper at the 1993 ADSA meetings, it has undergone peer
review and is currently in press. It evaluates sometribove and
summarizes full lactation studies from research in the U.S. and
Europe (914 cows) and short-term studies on commercial and research
farms in 8 countries (2697 cows). Although herds varied
considerably in mastitis related variables, there was no effect of
bST and bST did not alter typical relationships between herd
factors and incidence of clinical mastitis. This summary also
demonstrated that once all the major factors causing mastitis were
accounted for, there remained a small positive relationship between
milk yield and the incidence of mastitis when expressed on a per
cow basis, and bST treatment did not alter this relationship. This
is consistent with the FDA label on bST because any technology
which increases milk yield would increase mastitis incidence per
cow. This relationship between milk yield and mastitis cases per
cow is not unexpected because bacteria invade the mammary glands
via the teat canal and the longer the teat canal is open (i.e.
secretion of a larger volume of milk), the greater the probability
of bacteria entering the mammary gland. However, from both a
consumer and farmer perspective a more realistic evaluation of risk
is to consider cases of mastitis per volume of milk produced. When
expressed per unit of milk, mastitis incidence declined slightly as
milk yield increased and this relationship was not altered by
sometribove (12). Therefore, the higher producing bST-treated cow
presents a lower risk per unit of milk than the same cow not
administered bST.
Public discussion of new technology, including bST, is
important. However, this discussion is ill served when it focuses
on misinformation such as the earlier cited claims. Recently, C.
Everett Koop (former U.S. Surgeon General) issued a statement on
the approval of bST and addressed these same points as follows:
"Unfortunately, a few fringe groups are using misleading
statements and blatant falsehoods as part of a long-
running campaign to scare consumers about a perfectly
safe food. Their long-range goal is to prevent the
benefits of biotechnology from reaching the public.
Because dairy foods are an important, widely consumed
source of nutrition, it is necessary to condemn these
attacks on the safety of milk for what they are:
baseless, manipulative and completely irresponsible".
The research on bST is unprecedented for a new technology. Because
of the extensive cooperation and publication of results, there are
almost 2,000 scientific publications involving research by over
1,000 scientists in academia, government and industry as well as
several hundred dairy farmers involved in the field trials.
Results have been verified by scientific groups in the U.S. and
throughout the world. It is time to use this extensive knowledge
rather than the misinformation as basis for the public discussion
of bST.
1. Craven, N. 1991. Milk production and mastitis susceptibility:
genetic relationships and influence of bovine somatotropin
treatment. In: J. Espinasse (ed). Mammites des Vaches
Laitieres. Societe Francaise de Buiatrie. Dec. 18-19, 1991.
Paris, pp 55-59.
2. European Communities CVMP. 1993. Final Scientific Report of
the Committee for Veterinary Medicinal Products on the
Applications for Marketing Authorization. Reports on
Recombinant Bovine Somatotropin issued to Eli Lilly Co.
(Optiflex 640, 640 mg Somidobove) and Monsanto Co. (Somatech,
500 mg Sometribove) on 01/27/93, Brussels.
3. FDA. 1993. Food and Drug Administration Veterinary Medicine
Advisory Committee Hearing on Bovine Somatotropin
(Sometribove). March 31, 1993 in Gaithersburg, MD.
4. Ferguson, J. D. 1990. Bovine somatotropin-reproduction and
health. In: Bovine Somatotropin. NIH Technology Assessment
Conference Proceedings. Dec. 5-7, 1990. Bethesda, MD, pp 65-
81.
5. McClary, D. G., H. B. Green, R. P. Basson, S. C. Nickerson, M.
J. Overpeck-Alvey, and D. L. Turner. 1991. Incidence and
duration of clinical mastitis in lactating dairy cows
receiving a sustained-release formulation of bST (somidobove).
J. Dairy Sci. 74(Suppl. 1):205(Abstract).
6. Monsallier, G. 1991. Somatotropine bovine: impact sur la sante
des mamelles. In: J. Espinasse (ed). Mammites des Vaches
Laitieres. Societe Francaise de Buiatrie. Dec. 18-19, 1991.
Paris, pp 60-67.
7. Moore, D. A., and L. J. Hutchinson. 1992. BST and animal
health. In: M. C. Hallberg (ed). Bovine Somatotropin and
Emerging Issues: An Assessment. Westview Press, Boulder, pp
99-141.
8. Phipps, R. H. 1989. A review of the influence of somatotropin
on health, reproduction, and welfare in lactating dairy cows.
In: K. Sejrsen, M. Vestergaard, and A. Neimann-Sorensen (eds).
Use of Somatotropin in Livestock Production. Elsevier Applied
Science, NY, pp 88-119.
9. Schmitz, F., R. W. Everett, and D. M. Galton. 1993. Milk and
somatic cell count response to sometribove (recombinant
methionyl bovine somatotropin) in five New York field trial
herds. J. Dairy Sci. 76(Suppl. 1):164 (abstract).
10. Sears, P.M. 1990. Udder health and BST: Is there a need for
concern? Proc. 22nd Annual Convention of American Association
Bovine Practitioners, pp. 86-87.
11. Thomas, J. W., R. A. Erdman, D. M. Galton, R. C. Lamb, M. J.
Armbel, J. D. Olson, K. S. Madsen, W. A. Samuels, C. J. Peel.,
and G. A. Green. 1991. Responses by lactating cows in
commercial dairy herds to recombinant bovine somatotropin. J.
Dairy Sci. 74:945-964.
12. White, T. C., K. S. Madsen, R. L. Hintz, R. H. Sorbet, R. J.
Collier, D. L. Hard, G. F. Hartnell, W. A. Samuels, G. de
Kerchove, F. Adriaens, N. Craven, D. E. Bauman, G. Bertrand,
Ph. Bruneau, G. O. Gravert, H. H. Head, J. T. Huber, R. C.
Lamb, C. Palmer, A. N. Pell, R. Phipps, R. Weller, G. Piva, Y.
Rijpkema, J. Skarda, F. Vedeau, and C. Wollny. 1994.
Clinical mastitis in cows treated with sometribove
(recombinant bovine somatotropin) and its relationship to milk
yield. J. Dairy Sci. 76:(in press).
13. Wilkinson, J.I.D. 1993. Summary of Mastitis Incidence - 34
trials (922 cows) with bovine somatotropin (Eli Lilly Co.,
somidobove). Evaluated by the UK Medicines Commission on
01/15/93.
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Dottie Ceurter PH: 607-255-2262 FAX: 607-255-9829
Department of Animal Science, Cornell University, 262 Morrison Hall
Ithaca, NY 14853-4801
It's nice to be important, but it's more important to be nice.
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