Effects of Slaughter Knife Sharpness on Blood Biochemical and Electroencephalogram Changes in Cattle

Abstract

The sharpness of the knife used for slaughter is of the utmost importance from an animal welfare perspective. The quantification of knife sharpness is almost impossible in abattoirs. The sharpness of the knife blade used to slaughter an animal, as well as its effects on animals’ pain and stress levels, is an important area of investigation that needs to be addressed. The objective of this study was to evaluate the effects of knife sharpness on blood biochemical parameters, plasma catecholamines, and electroencephalographic (EEG) responses. Twenty Brahman crossbred steers were either subjected to slaughter with a sharp knife (n = 10) or a commercial sharp knife (n = 10); knife sharpness was measured with the ANAGO® sharpness tester. There was significant increase in adrenaline (p < 0.0001), glucose (p = 0.0167), creatinine kinase (p = 0.0123) and lactate dehydrogenase (p = 0.0151) at post-slaughter compared to pre-slaughter in commercial sharp knife group than in thesharp knife group. A significant increase was observed in the median frequency (p < 0.0001) and total power (p < 0.0001) of the EEG, the parameters for pain and stress, in the animals slaughtered with the commercial sharp knife than those slaughtered with the sharp knife. Thus, EEG results also supported the hormonal and biochemical results. From the results, it is concluded that animals slaughtered with a sharp knife experienced the least amount of pain and stress compared to those slaughtered with a commercial sharp knife.

Pain at the Slaughterhouse in Ruminants with a Focus on the Neurobiology of Sensitisation

“…Lesions or trauma also stimulate a neuroendocrine reaction due to the intricate connections between the two systems. This reaction has three components: (1) the sympathetic-adrenomedullary (SAM) response mediated by catecholamines such as dopamine, noradrenaline and adrenaline, (2) Corticotropin-releasing hormone (CRH) activation of the hypothalamic-pituitary-adrenal (HPA) axis leading to production of glucocorticoids and (3) activation of the locus coeruleus and the noradrenergic limbic brain [ 2 , 23 , 24 ]. Limbic structures, including the hippocampus, amygdala and pre-frontal cortex have an inhibitory influence by resetting the HPA axis following a stressful event [ 25 ].…”

“…It has been suggested that following sticking in cattle, consciousness may last for 60 s or more [ 54 ]. During this period there is potential for animals to experience both pain and distress due to transection of a series of nociceptive fibers, that when activated generate a stream of sensory impulses that make pain perception inevitable [ 2 ]. In most jurisdictions, regulatory and guidance documents require that steps are put in place to mitigate the experience of pain associated with sticking.…”

“…Pain and distress arise due to the incision itself, which activates various nociceptors, but also due to sustained activation of the SAM system due to hypotension caused by bleeding. This causes tachycardia, tachypnea, hyperthermia and a redistribution of the blood [ 2 , 23 ].…”

“…It is imperative that all major blood vessels are severed to ensure time to death is reduced. The sticking process causes significant nociceptor stimulation [ 2 ], in addition to causing distress through method of restraint, as well as through aspiration of blood [ 3 , 4 ].…”

Welfare of cattle at slaughter

“…The origin of this hazard is identified to be lack of skilled operator and too short and /or blunt knife. Recently, Imlan et al (2020) evaluated the effects of knife sharpness on EEG responses in cattle. The results showed a significant increase in the median frequency and total power of the EEG, the parameters indicative of pain and distress, in the animals slaughtered without stunning by cutting soft tissues in the neck at the first cervical vertebra.…”