http://digitool.library.colostate.ed...8xNjM0Ng==.pdf

Time to loss of consciousness
Scientific researchers agree that sheep lose consciousness within 2 to l5 seconds after both carotid arteries are cut (Nangeroni and
Kennett, 1963; Gregory and Wotton, 1984; Blackmore, 1984). However, studies with cattle and calves indicate that most animals
lose consciousness rapidly, however, some animals may have a period of prolonged sensibility (Blackwore, 1984; Daly et al, 1988)
that lasts for over a minute. Other studies with bovines also indicate that the time required for them to become unconscious is more
variable than for sheep and goats (Munk et al., 1976; Gregory and Wotten, 1984). The differences between cattle and sheep can be
explained by differences in the anatomy of their blood vessels.

Observations by the first author of both calf and cattle slaughter indicate that problems with prolonged consciousness can be
corrected. When a shochet uses a rapid cutting stroke, 95% of the calves collapse almost immediately (Grandin 1987). When a
slower, less decisive stroke was used, there was an increased incidence of prolonged sensibility. Approximately 30% of the calves
cut with a slow knife stroke had a righting reflex and retained the ability to walk for up to 30 seconds.

Gregory (1988) provided a possible explanation for the delayed onset of unconsciousness. A slow knife stroke may be more likely
to stretch the arteries and induce occlusion. Rapid loss of consciousness will occur more readily if the cut is made as close to the jaw
bone as religious law will permit, and the head holder is loosened immediately after the cut. The chin lift should remain up.
Excessive pressure applied to the chest by the rear pusher gate will slow bleed out. Gentle operation of the restrainer is essential.
Observations indicate that calm cattle lose consciousness more rapidly an