Citat fra EFSA – det europæiske ekspertpanel i EU vedr. spørgsmål om
dyrevelfærd, rapport 2004:
(Der findes ikke nyere rapporter på dette fagområde)
ESFA`s konkluderende anbefaling:
2.1.2. Recommendations
The penetrating captive bolt should be used for cattle and
calves. The non-penetrating captive
bolt stunning method available at present is unreliable and
should not be used.
Citat fra rapporten:
7.1.2. Non-penetrating captive-bolt-stunning
To ensure effective stunning in adult cattle, the captive bolt must be placed 2 cm above
the cross-over point of imaginary lines drawn between the base of the horns and the
63
contralateral eyes (HSA, 1998). Proper restraint of the animal and fixation of the head
allows adequate positioning of the instrument and shooting of the animal.
Studies on 12 adult cattle found that frontal non-penetrating captive-bolt-stunning
(Figure 7-2) resulted in immediate loss of consciousness in all animals, as indicated by
immediate collapse and, after brief tetanic spasms, in slow uncoordinated hindlimb
movements of increasing frequency (Finnie, 1995). Rhythmic breathing was absent. The
animals presented a depressed fracture of the frontal bone and widespread subarachnoid
haemorrhage, particularly beneath the impact site, in the temporal and frontal lobes, and
around the brainstem. Petechial haemorrhage was observed in the basal ganglia and
thalamus. Duration of unconsciousness has not been reported as animals were
immediately bled.
A recent field study (Moje, 2003) on non penetrating captive bolt stunning on about
1200 cattle in 2 abattoirs found that 20 to 30% needed an immediate re-stun. Depending
on the abattoir, more than 90% or 40% of the animals showed skull fractures. The author
concludes that from the animal welfare point of view the method is unsatisfactory, due to
the relative high failure rate. He suggests that improvement of the shape of the bolt,
better fixation of the head, and standardisation of cartridge power, may improve the
results. He further indicates the necessity of rapid sticking.
Electroencephalic studies found that frontal non-penetrating captive-bolt-stunning (Cash
knocker, cartridges for light weight cattle) produced immediate unconsciousness in 80%
of 31 calves (6 months, 200 kg; Lambooij et al., 1981). Increasing cartridge force may
help to improve efficiency, but may also cause skull bone fracture. In the latter case,
efficient stunning may be more difficult to obtain as the skull absorbs part of the impact,
the kinetic energy transferred to the brain is reduced proportionally to the extent of the
fracture (Von Wenzlawowicz, pers. comm., 2003). Another study found that 80% of 90
calves (1 to 2 weeks of age, Hantover knocker, using air pressures of between 35 and
50 kg/cm2) were effectively stunned as determined by behavioural observations
(Blackmore, 1979).
In calves, outward signs of effective non-penetrating captive-bolt stuns were described as
the appearance of 5-15 sec tonic convulsions and spasms prior to relaxation, or of
extensor rigidity and some generalised muscular tremors, followed by slow hind leg
movements, developing into vigorous hind leg kicking (clonic spasms or convulsions)
(Blackmore, 1979; Lambooij et al., 1981). Absence of the righting reflex lasted at least
60 sec. In effectively stunned calves, palpebral, corneal, labial, spinal and digital reflexes
were absent, but the corneal reflex often returned within 20 sec, while respiration
stopped for up to 35 sec (Blackmore, 1979). These observations suggest that duration of
unconsciousness depends on the animal and on the impact energy, but could last 20 to 35
sec In addition, nystagmus (involuntary, rhythmical, repeated oscillations of one or both
eyes), inward rotation of the eyes and a reflex vocal response were frequently observed
immediately following the stun. Inward rotation of the eyes may indicate that the state of
unconsciousness is not profound (Gregory, 1998).
Non-penetrating captive bolt stunning was accompanied by gross brain haemorrhage in
50 to 100% of the calves (Blackmore, 1979; Lambooij et al., 1981). In calves, occipital
non-penetrating captive bolt stunning (Figure 7-3) had a lower success rate (3 out of 8
calves) than frontal application (15 out of 19 calves) and therefore, occipital shooting is
less effective and not advisable (Lambooij et al., 1981).
efficient (Anil et al., 1995b) and should be rapid to avoid the return of consciousness. As
the stun may last as short as 20 sec (determined for calves; no data for cattle), and as
chest sticking induces a blood pressure of near 0 after about 8 sec (Anil et al., 1995b),
animals should be chest stuck no later than 12 sec after the stun.
Summarising, limited data show that frontal non-penetrating captive bolt stunning
induced unconsciousness in 100% of the adult cattle and in 80% of calves. Occipital
non-penetrating captive bolt stunning in calves had an even lower success rate.
7.1.2.1. Description of effective use
Since the duration of insensibility induced by this method could be as short as 20 sec,
animals should be bled as soon as possible after stunning.
The air has to be sufficiently compressed or the cartridge chosen has to produce
sufficient velocity to stun the animal.
A penetrating captive bolt as a backup stunning device is essential.
7.1.2.2. Monitoring points
Effective non-penetrating captive bolt stunning produces the same outwardly signs as
penetrating captive bolt stunning (see 7.1.1.2.).
7.1.2.3. Advantages
There are no animal welfare advantages compared to penetrating captive bolt stunning
7.1.2.4. Disadvantages
Non-penetrating captive bolt stunning is not always effective for all types of animals.
When the skull is immature, bones (calves) may be crushed and the impact may be
insufficient. When the skull is very thick (bulls), the power of the gun may be
insufficient. Occipital and temporal non-penetrating captive bolt stunning should be
avoided.
The duration of unconsciousness is relatively short. Animals should be chest stuck
within 12 sec.
7.1.3. Free bullet
Free bullets are not used in slaughterhouses, except under exceptional conditions (their
use under disease control situations will be described in chapter 13)