Physiological and electroencephalogram responses in goats subjected to pre-and during slaughter stress

Abstract

A comprehensive stress assessment is vital in understanding the impact of the pre-slaughter procedure on animal welfare. The transportation and handling process was commonly reported to cause stress in animals. This research utilises electroencephalography (EEG) as an alternative stress indicator to non-painful acute stress measurement. EEG has been proved to be instantaneous and sensitive with specific results. Therefore, this study was aimed to determine the stress level of goats subjected to two different transportation duration and the effect of lairage based on their EEG activities and blood parameters changes. Eighteen adult male goats were divided into two transportation stress groups based on the transport duration: the two-hour (TS2) and six-hour (TS6) groups. Then, each group was then again divided into three smaller groups according to the lairage duration, which was three-hour (L3), six-hour (L6), and overnight (L12) groups. Blood was sampled before transport, after transport, and during slaughter while EEG was recorded before transport, after transport, after lairage, and during slaughter. Results revealed that there was a significant decrease in beta wave activity compared to baseline in TS2 goats (P < 0.05) after transportation, whereas no significant difference was detected in the TS6 goats. At the same time, goats from the TS2 group showed increase in creatine kinase (CK) and lactate dehydrogenase (LDH) compared to that in TS6 goats. Together with the observed cortisol concentration, these findings showed that the TS6 goats were fully adapted to the transportation stress while the TS2 goats were still under stress. As for the lairage duration, it was observed that the TS2L3 goats showed lower EEG activities than the values obtained after two-hour transportation, while lower EEG activities were found from the TS6L6 goats after six-hour transportation. Therefore, it can be concluded that three-hour lairage was adequate to lower the impact of two hours transportation stress, whereas six-hour lairage was required to reduce the impact of six hours transportation stress. Finally, it was also found that the TS6L3, TS6L6, and TS6L12 groups took a long time to die after slaughter than the TS2L3, TS2L6, and TS2L12 goats based on the time their EEG activity reached isoelectric.

Electroencephalogram and Physiological Responses as Affected by Slaughter Empathy in Goats

“…Various slaughter environments could be attributed to the increase in the alpha waves. The alpha waves were also recorded as significantly higher in lairage compared with the baseline value after 6 h of transportation in goats [ 31 ]. An increase in alpha wave activity was also recorded in lambs and goats after head-only and head-to-back electrical stunning [ 39 ].…”

“…In humans, a higher beta power was recorded under stressful conditions [ 42 ]. Several studies have recorded an increase in the beta waves during stress in animals such as during the transportation and slaughter of goats [ 31 , 32 ].…”

“…The delta waves followed a similar trend to that of the alpha waves with the treatment phase having higher but comparable values to the control phase. Higher delta waves were recorded in goats during slaughter compared with the corresponding value at the farm [ 31 ]. These waves are associated with a brain’s default mode network [ 43 ].…”

“…It is a technology used to measure the electric activity of neurons in the cerebrocortical region of the brain by fixing electrodes on various positions of the brain [ 28 , 29 ]. The electric activity of neurons was used to assess pain and stress in animal welfare during the slaughter process in goats [ 30 , 31 , 32 , 33 ]. However, the high cost of equipment, experimental conditions, and analysis still remain issues in its popularization.…”

Application of Electroencephalography in Preslaughter Management: A Review

“…Raghazli et al [ 123 ] utilized the EEG as an alternative, sensitive, painless tool for the instantaneous measurement of acute stress in goats in Malaysia. The authors studied the effect of transportation duration (2 h and 6 h) and lairage time (3 h, 6 h, and 12 h) on EEG variables and blood parameters.…”