Background: Accepting that it is ethical for meat to be consumed as food, then, in any context, religious or secular, it is indefensible for animals to be subjected to undue pain. Animal slaughter must therefore be predicated on the minimization of pain. Nonstun slaughter (NSS) of bovines involves ventral neck incisions, resulting in an abrupt loss of cortical blood flow and causing nearly instantaneous loss of consciousness (LOC). However, some reports have suggested that LOC after NSS is not instantaneous. This paper presents an overview of the neurobiology underlying NSS and a systematic review of the literature on time to LOC in bovines following NSS. Methods: A literature review was conducted across PubMed, Google Scholar, the Cochrane Library, Medline, and the Web of Science, with 3 coauthors independently screening articles to reduce bias. Only original research and review articles specifically addressing time to LOC in bovines after NSS were included; studies not focused on this outcome were excluded. The quality of evidence was ranked based on hierarchy of evidence utilizing predefined criteria. Results: 15 studies were identified: 4 high quality, 3 medium quality, and 8 low quality. High-quality evidence consistently indicates that LOC occurs within 10 seconds of NSS of bovines when done correctly with low-stress, ideal slaughterhouse conditions. Clinical Relevance: Our findings provide important insights to optimize NSS practices, promoting animal welfare while maintaining religious requirements.

Objective: To investigate the hemodynamic consequences of carotid sectioning, as performed in religious slaughter, on cerebral blood flow (CBF) and pressure in cattle. Religious slaughter typically does not allow preslaughter stunning, which has led to scrutiny over concerns that blood flow from intact vertebral arteries or vascular occlusions could delay loss of consciousness and potentially result in unnecessary pain and suffering. Methods: A numerical model of the bovine cerebrovascular system was developed using COMSOL Multiphysics, incorporating anatomical and physiological parameters. Simulations were conducted across pre, immediate, and postcarotid sectioning states and scenarios involving vessel occlusions. Results: The simulation revealed a near-instantaneous loss of approximately 99% of CBF and pressure immediately following carotid sectioning. Vertebral artery flow is redirected away from the brain, via the vertebral-occipital anastomosis, toward the severed carotids. Simulated carotid occlusions did not meaningfully alter cerebral hemodynamics or delay the loss of blood flow and pressure. Conclusions: Carotid sectioning causes an almost complete and immediate cessation of cerebral perfusion, with vertebral artery flow and carotid occlusions exerting negligible influence. The results support the conclusion that religious slaughter methods, such as shechita and halal, in which the major blood vessels are severed, induce rapid loss of CBF and pressure and therefore rapid loss of consciousness. Clinical Relevance: This work underscores the value of numerical modeling in providing objective insights into the hemodynamics of religious slaughter without causing undue harm to any animals and confirms prior findings of a precipitous drop in blood pressure and flow following the incision.

Background: Electroencephalographic (EEG) methods have been employed to evaluate pain-related neurophysiologic responses during slaughter of cattle and have contributed to scientific discussions informing slaughterhouse regulations. The interpretation of EEG changes as pain remains controversial. This systematic review critically evaluates the literature on EEG used to infer pain during slaughter and other forms of noxious stimuli. Methods: A systematic review was conducted in accordance with Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. PubMed/MEDLINE, Web of Science, Scopus, and Google Scholar were searched. Included studies evaluated EEG responses to slaughter or other forms of noxious stimuli in cattle. Risk of bias was assessed using ROBINS-I. Results: 9 studies met inclusion criteria. Electroencephalographic changes following ventral neck incision and other noxious stimuli were characterized by transient increases in high-frequency activity and shifts in spectral indices (F50, F95, Ptot). The risk of bias across studies was judged to be moderate. Clinical Relevance: Current evidence suggests that electrophysiologic changes observed after ventral neck incision may reflect nociception, defined as neural signaling in response to a noxious stimulus, but do not establish conscious pain perception, which requires preserved consciousness and integrated cortical function. In the context of slaughter, the observed EEG changes likely reflect rapid hemodynamic and metabolic deterioration of cortical function. Findings are limited by methodological heterogeneity, reliance on surface EEG recordings, motion artifacts, small sample sizes, and inherent limitations of EEG in localizing deep pain-processing structures and indirect inference of pain from EEG activity.