final report - ARCHIVE: Defra

Management tools
7.6.3 An additional problem is that high-density badger populations contain a considerable reserve of spare
breeding capacity amongst females. This means that fertility control is unlikely to cause a substantial
reduction in cub numbers unless the uptake rate of the agent in question, and its efficacy, are very
high. For this reason and others, models suggest that fertility control alone is unlikely to constitute an
effective means of controlling bTB prevalence, though it could conceivably have a role in combination
with culling (Swinton et al., 1997; White et al., 1997). The results of a recent field trial of fertility
control (by gonadectomy) in brushtail possums are no more encouraging, insofar as they showed no
overall effect on the rate of transmission of bTB within the possum population (Ramsey et al., 2006).
7.6.4 In conclusion, we see no reason to depart from the view of Krebs et al. (1997, p. 86) that fertility
control has little potential value as a bTB management tool. Research in this area should not be given
high priority.
7.7 Farm husbandry measures
7.7.1 Research has shown that visits by badgers to farm buildings could result in direct or indirect transmission
of bTB to cattle (see sections 4.6 and 7.1.8 above). Although this evidence is circumstantial in nature,
enough has been done to suggest that substantial numbers of farms are subject to visits by badgers.
From the point of view of management, the implication is that enhanced biosecurity, for example
by preventing badgers from accessing cattle sheds or feed stores, might reduce the risk of herd
breakdowns.
7.7.2 A likely bar to getting farmers and vets to take biosecurity seriously is the absence of any direct evidence
that it would reduce the risk of a herd breakdown (EFRA Committee, 2008, p. 46). In principle, the
relevant evidence could be collected but this would require a trial on the scale of the RBCT. In addition,
different farms are attractive to badgers for different reasons, making it impossible to identify a single
biosecurity measure, or a limited set of measures, that could be manipulated in an experimental test.
7.7.3 We conclude, therefore, that, notwithstanding the desirability of assessing, in a formal scientific
manner, the efficacy of enhancements to farm biosecurity, cost and other logistical considerations
make this impractical. However, provided that Defra knows about any biosecurity measures that
farmers implement, it should be possible, in the long term, to build up a case–control database that
would enable efficacy to be assessed. This depends on Defra opening and maintaining an effective
communication channel with farmers on biosecurity matters (see below and section 6).
7.7.4 One important finding from the relevant studies is that not all farms are attractive to badgers. Identifying
the reasons why some farms are visited by badgers while others are not is an important research
priority and is part of the remit of an ongoing project (SE3119). Depending on the outcome of that
project, further research in this area may be justified. In addition, more research may be needed into
the effectiveness and cost-effectiveness of different ways of deterring badgers, since electric fencing
is unlikely be a practicable solution in many cases. Above all, however, Defra needs to find ways of
persuading the farming community that a reasonable level of biosecurity makes sense, and this may be
a subject for research as well as for policy decisions (see also section 6).
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