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CHAPTER 7
TABLE 3
Time post cut (mean ± SD, range (s)) to indicators for loss of consciousness in sheep slaughtered without prior stunning. Reference
N
Indicator for loss of consciousness
Observed time post cut (s) mean ± SD (range)
Nangeroni and Kennet (1963)
5
Relevant EEG changes
7 ± 5 (3-15)
Schulze et al. (1978)
17
Relevant EEG changes
4-61
Newhook and Blackmore (1982b)
5
EEG amplitude <10 μV and > 35 μV
2-7
Gregory and Wotton (1984)
20
Time to loss of brain responsiveness determined from VEPs2
14 ± 1
Blackmore (1984)
33 2
Loss of ability to stand and loss of apparent coordinated attempts to rise
3 ± 1 (2-3) 4 ± 1 (3-4 )
Loss of apparent coordinated attempts to rise
10 ± 1 (9-11) 9 ± 1 (8-9)
EEG amplitude <10 μV
14 ± 7 (8-22)
Devine et al. (1986) Tidswell et al. (1987)
4
2
Kallweit et al. (1989)5
4
3
9 Verhoeven et al. (2015b)
21
3
Decline of EEG to <10 μV
7 and 8
ECoG iso-electric
13 (5-20)
EcoG iso-electric
12 (8-17)
Start of high amplitude, low frequency EEG
15 ± 4 (6-24)
Cited by von Holleben et al. (2010) who stated that the original report and data of the project Hazem et al. (1977) revealed that, though the authors concluded loss of consciousness being highly probable after 4 to 6 seconds in the publication, they recorded unchanged EEG until 8 seconds after the cut and concluded in the original report that sheep lost consciousness latest 10 seconds after the neck cut. 2 Visual evoked potentials. 3 Lambs. 4 Observations following decapitation. 5 Cited by von Holleben et al. (2010). Four sheep were non-stunned slaughtered according to halal rites and 9 sheep were non-stunned slaughtered according to shechita rites. 1
Terlouw et al. (2016a) observed loss of consciousness in chickens and turkeys after on average 35 s, ranging in chickens from 12 to 202 s and in turkeys from 18–51 s (Bourguet, Deiss and Terlouw, personal observations, cited by Terlouw et al., 2016a). Some of the variation between studies can be attributed to different indicators used to assess times to loss of consciousness. Indicators used in the different cited studies consisted of loss of standing posture (Gregory et al., 2010), onset of low frequency activity (Nangeroni and Kennett, 1963) loss of evoked potentials (Daly et al., 1988) or changes in EEG activity (Verhoeven et al., 2015b; Verhoeven et al., 2016a). But even within a single study, the variation between animals remains large. Gregory et al. (2010) observed an average time to collapse of 20 s after the neck cut in 174 cattle. In 8% of those cattle, however, it took 60 s or more to collapse after severing both carotid arteries. Two phenomena are believed to contribute to prolonged consciousness in cattle during the bleeding phase. In a proportion of the slaughtered cattle, occlusion of the severed arteries, and therefore impaired bleeding out may occur. Gregory et al. (2006) observed this in 25