Slaughtering of Water Buffalo (Bubalus bubalis) with and without Stunning: A Focus on the Neurobiology of Pain, Hyperalgesia, and Sensitization.

Simple Summary: Due to anatomical differences in the skull of the water buffalo (Bubalus bubalis), the currently applied mechanical stunning methods in cattle (genus Bos) have shown to be ineffective in buffaloes by not damaging vital cerebral structures associated with consciousness. The present review analyzes these anatomical particularities of water buffaloes to discuss the importance of selecting a stunning method suitable for the species to avoid pain and suffering. Potential pain-related processes such as hyperalgesia and sensitization are also addressed. In addition, the signs to assess stun quality and return to consciousness are discussed to elucidate the importance of recognizing these indicators and prevent physiological consequences and affectation to water buffaloes' welfare and quality of death. The slaughter process in livestock is considered a stressor where the transport and handling of animals, as well as the selected stunning and bleeding methods, can cause acute pain, distress, and suffering. In water buffaloes, although stunning is known to be performed before bleeding to induce unconsciousness, no emphasis is made on the nociceptive events during this process. Particularly, current mechanical stunning methods applied to cattle are unsuitable for water buffaloes due to anatomical differences in the skull from other large ruminants. Furthermore, although very high-pressure pneumatic (200–220 psi) may be effective in the frontal position for lighter-weight water buffalos, for heavier animals, it is less likely to be effective. The present review aims: (1) to analyze the anatomical particularities of water buffaloes to discuss the importance of selecting a stunning method suitable for buffaloes, and (2) to revise the potential pain-related consequences, such as hyperalgesia and sensitization, and the signs to assess the stun quality and death to comprehend the relevance of a proper technique according to the species. [ABSTRACT FROM AUTHOR]