This section applies AWIA to bovine TB and badger control policy. Three policy options are assessed:

(i) Do nothing. (ii) Badger culling. (iii) Badger vaccination.

Prior to the AWIA analyses, the species descriptions are provided in the section below.

AWIA: Species Descriptions

Tables 1 and 2 include species descriptions for the cow (or ox), Bos Taurus, and for the badger, Meles meles, respectively. The species descriptions include data that may influence decision making about policy options.

Table 1 AWIA species description—cow Full size table

Table 2 AWIA species description—badger Full size table

AWIA Analyses

The AWIA analyses for the three policy options are found in Tables 3, 4, 5, 6, 7 and 8.Footnote 8 Much of the data in the AWIA analysis tables are taken directly or extrapolated from a Natural EnglandFootnote 9 report documenting impacts of badger culling on the badger population (Natural England 2011). Based on the Natural England report, the badger population in England is considered to be 220,000 (Natural England 2011). The AWIA analysis for badger culling is based on achieving a 19% reduction in bovine TB in cattle. The number of badgers to be culled (85,000) is taken from the Natural England report, which assumes the granting of 33 cull licences using an average control area of 350 km2 over a four year period.Footnote 10 The 19% figure was proposed by the farming industry. It is based on the meeting of experts that was hosted by Defra to arrive at some consensus about the impact of badger culling, after the contradictory recommendations of the ISG and the King review. The 19% figure is larger than that the 12.4–16% reductionFootnote 11 agreed at the meeting of experts, itself based on the RBCT, because the culling areas are larger (350 km2) than those used in the RBCT (150 km2).Footnote 12

Table 3 AWIA analysis table—Policy option 1, ‘do nothing’, cow Full size table

Table 4 AWIA analysis table—Policy option 1, ‘do nothing’, badger Full size table

Table 5 AWIA analysis table—Policy option 2, ‘badger culling’, cow Full size table

Table 6 AWIA analysis table—Policy option 2, ‘badger culling’, badger Full size table

Table 7 AWIA analysis table—Policy option 3, ‘badger vaccination’, cow Full size table

The AWIA analyses compare impacts on cattle over a policy timeframe of 9 years. The impacts on badgers are based on the four year cull at the beginning of the 9 years. Natural England states that 4 years is the minimum cull period, but is expected to be the norm (Natural England 2011, p. 5).Footnote 13 Hence, since the AWIA analyses assess impacts on badgers for the 4 years of culling, this may underestimate the impacts on badgers, especially if culling licences are extended beyond 4 years. Indeed, in his report after the fourth year of culling in Somerset and Gloucestershire, the CVO recommends further annual culling to maintain the badger population at the suppressed level (Defra 2016a).

The ISG reported that 15% of road-killed badgers were infected with M. bovis. The prevalence was 16.6% in proactive cull areas (Bourne et al. 2007, pp. 74–76). Based on ISG data, Jenkins et al. report that 14% of badgers in proactive cull areas were tuberculous (Jenkins et al. 2008, p. 1530). Jenkins et al. have documented that unpublished studies have shown that more rigorous bacteriological examinations of RBCT badgers have revealed almost twice the number of sampled badgers were infected (Jenkins et al. 2008, p. 1358). Based on the same data, Donnelly reports that about 33% of RBCT badgers were actually infected (Donnelly 2013).Footnote 14 The figure of 33% of M. bovis-infected badgers in high incidence areas is used in this analysis.

The following sections discuss the AWIA analyses for the three policy options for badger control of (1) do nothing, (2) badger culling, and (3) badger vaccination.

Policy Option 1: ‘Do Nothing’

It is standard for government to have a ‘do nothing’ or minimal approach in its assessment of policy options. The do-nothing policy option here refers to badger-based measures alone. Hence, in the do-nothing policy option, bovine TB is controlled by cattle-based measures alone, such as tuberculin testing and slaughter of reactors, movement restrictions, slaughterhouse inspection of carcasses and on-farm biosecurity.

Cattle Population Impacts

The number of cattle slaughtered per herd breakdown is calculated by dividing the total number of cattle slaughtered by the number of new herd incidences. These figures are derived from Defra’s Quarterly publication on bovine TB incidence and prevalence in Britain (Defra and GSS 2016). The figures for high risk areas in England areas are 7.78 (26,185/3364) cattle slaughtered per new herd incident to end June 2016 and 6.72 (22,778/3392) to end June 2015. This analysis uses the mean of the figures for high incidence areas to end June 2015 and end June 2016, which is 7.25 ((7.78 + 6.72)/2). Hence, Defra’s data reveal that 7.25 cattle are slaughtered per new herd incident in high risk areas across June 2014–June 2016.

Thus, the baseline number of cattle culled in 33 high incidence areas is calculated by multiplying the estimated figure of 12,800 new breakdowns over 9 years without badger culling (Natural England 2011, p. 17) by the number of cattle culled per breakdown in high incidence areas (using Defra end June 2014–2016 figures). Hence, in the do-nothing policy option, 92,800 (12,800 × 7.25) cattle are estimated to be culled over a nine year timeframe.

Badger Population Impacts

The total badger population over 4 years in the 33 cull areas can be calculated based on the central estimate of 85,000 badgers culled and the objective to cull 70% of badgers. Therefore, if 85,000 is 70% of the badger population then the total badger population across 4 years in the 33 cull areas is 121,429 (85,000 × 100/70). Based on the total badger population in the 33 cull areas, estimates for welfare impacts can be made. Donnelly (2013) and Jenkins et al. (2008) report that 33% of badgers in high bovine TB incidence areas are infected with M. bovis. Hence, 40,072 (33% × 121,429) badgers are infected with M. bovis over 4 years. Jenkins et al. found that 1% of M. bovis-infected badgers in the proactive areas of the RBCT had extensive and severe lesions at necropsy (Jenkins et al. 2008, p. 1350). Hence, 401 (1% × 40,072) badgers can be assumed to suffer medium-duration, strong intensity, negative welfare due to M. bovis infection. Most badgers do not suffer severely from M. bovis infection (Defra 2010b; Jenkins et al. 2008). However, it can be assumed that M. bovis infection does have some degree of negative impact on quality of life. Hence, the 39,671 (40,072–401) M. bovis-infected badgers that do not have severe and extensive lesions are considered to experience a medium-duration, mild intensity, negative impact on welfare. Despite this, these badgers are considered to have a life of net positive value, since the negative impact of M. bovis infection is likely to be outweighed by other positive value in life.

Finally, the AWIA analysis in this paper is concerned with assessing the impacts of the policy options of (1) do nothing, (2) badger culling, and (3) badger vaccination. For simplicity and to facilitate comparing the impact of the three policy options, it is assumed that cattle and badger populations in general have a life of net positive value. The assumption is to provide a baseline but is not arbitrary. To illustrate, if a cow has a life of net positive value, then M. bovis infection, since it leads to slaughter, causes a (very) negative impact. However, if that cow had a life of net negative value (for instance due to chronic severe lameness), infection with M. bovis and consequent culling would in fact be a positive impact, since her death would be the end of her suffering.

Policy Option 2: ‘Badger Culling’

Cattle Population Impacts

The Natural England report to Defra includes a section on the potential benefits for bovine TB control based on industry proposals in Annex D (Natural England 2011, p. 17). The report uses the ‘Donnelly model’, which estimates bovine TB incidence based on 5 years of badger culling, followed by 4 years of non-culling (Jenkins et al. 2010). As the Natural England report states, because licensing criteria are based on a four year cull, using the Donnelly model may overestimate the benefits of the proposed government badger culling policy. Based on the Donnelly model, without badger culling, there would be ~12,800 new breakdowns over the nine year period in 33 control areas. Based on the Donnelly Model’s 5 years of culling and a four year post-cull period, there would be ~10,350 (19% reduction) new herd incidents, or a reduction of 2450.

As discussed in policy option 1, the mean number of cattle slaughtered per new herd incident from end June 2014 to 2016 is 7.25. Hence, the total number of cattle slaughtered in the badger culling policy option is 75,038 (10,350 × 7.25) Based on these figures, a 19% reduction in bovine TB incidence due to badger culling would mean 17,763 (2450 × 7.25) fewer cattle slaughtered. Additional to the harm of killing, cattle culled due to bovine TB can be assumed to suffer short-duration, moderate-strong intensity, negative welfare due to the transportation, lairage and slaughter process (FAWC 2003). Thus, a 19% reduction in bovine TB incidence results in 17,763 cattle avoiding this negative welfare impact due to being prematurely culled over a nine year timeframe.Footnote 15

Badger Population Impacts

For badgers, direct non-killing welfare impacts are defined as the welfare impacts caused directly by the methods of being shot. The government controlled/free-shooting humaneness target for the pilot badger culls was fewer than 5% of badgers taking over 5 min to die after being shot. The IEP reported that 7.4–22.8% of badgers took over 5 min to die (IEP 2014). The AWIA uses the central estimate of 15.1% of badgers, based on the IEP figures. The IEP also reported that cage trapping and shooting was used extensively in the pilot culls. After a Freedom of Information Act request, it was revealed that around 75% of badgers culled in the 2013 Gloucestershire and Somerset pilot culls were cage-trapped and shot (Press Association 2014). The Defra summary report of the 2016 culls reveals that 55% of badgers were culled using controlled/free-shooting and 45% using cage-trap and shooting (Defra 2016c). The AWIA assumes that 50% of badgers are killed by controlled/free-shooting and 50% by cage trapping and shooting across the 4 years of culling. The AWIA accounts for the welfare impacts of the 15.1% of badgers in controlled/free-shooting taking over 5 min to die as short-duration, strong intensity, negative welfare. Cage trapping wild animals such as badgers also causes negative welfare. The AWIA accounts for the impact of cage-trapping badgers as short-duration, moderate intensity, negative welfare.

Indirect non-killing welfare impacts are defined as welfare impacts due to the culling process other than direct impacts. Based on the RBCT, the ISG found that badger culling causes social disruption of badger groups, which leads to perturbation (Bourne et al. 2007; Woodroffe et al. 2006). The best explanation for the cause of perturbation due to the culling process is stress caused to the badger population by the activity of culling. The process of badger culling includes killing individual badgers and causing disruption of social groups due to these deaths. Further stress and perturbation is likely to result from the loud sounds of shots being fired. There are no data to quantify the indirect non-killing welfare impacts of culling, i.e. the stress caused to the local badger population. It is estimated here that 25% of the population experience indirect non-killing negative welfare due to culling causing disruption of social groups.Footnote 16

Policy Option 3: ‘Badger Vaccination’

There are no direct scientific data on how the BCG vaccination affects transmission of M. bovis from badgers to cattle. It has been shown that inoculation results in a 73.8% reduction in positive serological test results for M. bovis in badgers (Chambers et al. 2011, p. 1913). Defra recommends the vaccination of badgers around culling zones to reduce the impact of perturbation (Defra 2011b, p. 10). BadgerBCG can reasonably be assumed to have some positive impact on the reduction of transmission of M. bovis from badgers to cattle. However, there are no data to quantify this impact.

For the purpose of illustration, the AWIA analysis for badger vaccination is based on the following. First, an assumption is made that BadgerBCG reduces the transmission rate of M. bovis from vaccinated badgers to cattle by 50%.Footnote 17 Secondly, Donnelly and Nouvellet report that badgers are responsible for 50% of cattle reactors in high TB-incidence areas. This includes initial badger-cattle transmission (5.7%) and subsequent cattle–cattle transmission (94.3%) (Donnelly and Nouvellet 2013). Using the assumption of the efficacy of BadgerBCG to reduce badger-cattle transmission rates, the findings of Donnelly and Nouvellet, and the number of badgers vaccinated, the impact of badger vaccination can be estimated. The figures in the AWIA analysis in Tables 7 and 8 are based on the vaccination of 50% of the badger population in control areas.

Table 8 AWIA analysis table—Policy option 3, ‘badger vaccination’, badger Full size table

Cattle Population Impacts

Based on the assumptions and figures above, the impact of badger vaccination on bovine TB incidence, and thus the number of cattle culled as reactors, can be estimated. The AWIA analysis estimates that badger vaccination will result in 11,600 fewer cattle being culled over a 9 year timeframe. This figure is derived in the following way: 92,800 (cattle slaughtered, do nothing) × 0.5 (badger wildlife reservoir causing 50% reactors) × 0.5 (50% badgers vaccinated) × 0.5 (assumption of BadgerBCG reduced badger-cattle transmission efficacy) = 11,600. Thus, the number of cattle culled over a 9 year timeframe in the badger vaccination policy option is estimated to be 81,200 (92,800–11,600).

As for the do-nothing and badger culling policy options, slaughtered cattle are assumed to experience short-duration, moderate-strong intensity, negative welfare due to transportation, lairage and slaughter process. Thus, badger vaccination results in 11,600 fewer cattle experiencing this degree of negative welfare as a result of being culled as bovine TB reactors.

Badger Population Impacts

Chambers et al. (2011, p. 1913) have shown that BadgerBCG reduces positive serological test results in badgers by 73.8%. As discussed in the do-nothing policy option, Donnelly (2013) and Jenkins et al. (2008) report that 33% of badgers in proactive areas in the RBCT were infected with M. bovis. Around 1% of tuberculous badgers had extensive and severe lesions at necropsy (Jenkins et al. 2008). The AWIA analysis for the do-nothing policy option found that the majority of the 33% of M. bovis-infected badgers experience medium-duration, mild intensity, negative welfare impact. However, this is outweighed by other positive value in their lives, so this group of infected badgers still have a life of net positive value. Hence, if BadgerBCG vaccination reduces M. bovis infection by ~75% (73.8%), 15,027 (121,429 badger population × 33% population M. bovis-infected × 50% population vaccinated × 75% BadgerBCG efficacy) benefit from vaccination. Of the 1% (401) of M. bovis-infected badgers suffering from extensive and severe lesions in the baseline do-nothing policy, BadgerBCG results in a medium-duration, strong intensity, positive welfare impact in 150 badgers (401 suffering badgers × 50% badger population vaccinated × 75% BadgerBCG efficacy). Since these badgers were assumed to die from M. bovis infection, BadgerBCG vaccination results in 150 badgers avoiding death. The remaining 14,877 badgers (15,027–150) experience a medium-duration, mild intensity, positive welfare impact due to inoculation. Finally, the cage-trapping of wild species such as badgers can be assumed to cause moderate negative welfare. Thus, 60,715 badgers (121,429 total population × 50% population vaccinated) over a 4 year timeframe experience short-duration, moderate intensity, negative welfare due to the inoculation process.

Summary of Killing Impacts of Bovine TB Policy Options

Arguably, it is the killing impacts, for both cattle and badgers that are most relevant in AWIA of bovine TB policy options. Table 9 summarises the killing impacts of bovine TB policy options.

Table 9 Killing impacts of bovine TB policy options Full size table

The 17,763 cattle not slaughtered as a result of badger culling is based on the 19% reduction in bovine TB incidence. The figure is based on Natural England’s advice to Defra (Natural England 2011). Based on the AWIA vaccination policy option model and its assumptions in this analysis, badger vaccination is estimated to reduce the number of cattle culled by 11,600, which represents a 12.5% reduction in bovine TB incidence. With respect to the badger population, the badger culling policy involves the killing of 85,000 badgers over 4 years. The number of badgers culled over the nine year policy timeframe would ultimately depend on whether culling was extended beyond the original 4-year culling licences granted by Natural England. The do-nothing and badger vaccination policies do not involve the culling of badgers.

These figures are consistent with the Natural England advice to Defra (Natural England 2011). Natural England reported that ~30–50 badgers would be killed for each TB breakdown in cattle. The figures of 85,000 badgers culled to avoid the slaughter of 17,763 means that 4.785 badgers are killed for every cow which avoids slaughter. The AWIA has calculated that each herd breakdown results in ~7.25 cattle slaughtered. Hence, 34.69 (4.785 × 7.25) badgers are culled to prevent each bovine TB herd breakdown in cattle.