Hernandez Elein, James Fiona, Torrey Stephanie, Widowski Tina, Schwean-Lardner Karen, Monteith Gabrielle, Turner Patricia V
Department of Pathobiology, University of Guelph, Guelph, ON, Canada.
Department of Clinical Studies, University of Guelph, Guelph, ON, Canada.
Front Vet Sci. 2019 Sep 3;6:297. doi: 10.3389/fvets.2019.00297. eCollection 2019.
This study investigated changes in the electroencephalograph (EEG) power spectrum as well as physiological and behavioral responses to on-farm killing via mechanical cervical dislocation (MCD), manual cervical dislocation (CD) or intravenous pentobarbital sodium administration in lightly anesthetized laying hens, to evaluate the welfare impact of each method. A mixed group of 44 white Leghorn and Smoky Joe laying hens (60 weeks-old) were anesthetized with isoflurane in oxygen and maintained at 1.5-2% isoflurane/O until the killing method was applied. Birds were randomly assigned to one of three experimental groups on each trial day. The EEG was recorded bilaterally in a four-electrode montage. After recording a 5-min baseline, the killing method was applied and EEGs and other behavioral and physiological responses, including convulsions, gasping, cessation of body movements and feather erection were recorded for 5 min. Changes in EEG frequency bands (alpha, beta, delta, theta), median frequency (F50), 95% spectral edge frequency (F95), and total power (Ptot) were used to assess the quality of the on-farm killing event. Within 15 s after administration of pentobarbital sodium, there were significant decreases in mean frequency bands, increases in mean F50 and F95, and decreases in Ptot, suggesting brain death. In addition, birds presented a shorter latency to cessation of movement after pentobarbital sodium injection compared to MCD and CD (22 vs. 115 s and 136 s, respectively). There were significant increases in F95 and decreases in Ptot at 120 s after application of CD; and a concomitant decrease in the frequency bands at 135 s and isoelectric EEG at 171 ± 15 s. Changes consistent with brain death after MCD included isoelectric EEG at 207 ± 23 s and a significant decreases in some frequency bands at 300 s post-application. No other significant spectrum frequency changes were observed in the MCD group, suggesting brain death likely occurred near the 5-min endpoint. There was no clear association between behavioral, physiological, and EEG responses within CD and MCD treatments. The data demonstrate that pentobarbital sodium induced a rapid death with minimal behavioral and physiological responses regardless of strain of hens. In comparison, use of CD and MCD resulted in a slow onset of brain death in hens.
本研究调查了轻度麻醉的蛋鸡经机械颈椎脱臼（MCD）、手动颈椎脱臼（CD）或静脉注射戊巴比妥钠进行农场宰杀时脑电图（EEG）功率谱的变化以及生理和行为反应，以评估每种方法对福利的影响。一组由44只白来航鸡和烟熏乔蛋鸡（60周龄）组成的混合群体用异氟烷在氧气中麻醉，并维持在1.5 - 2%的异氟烷/氧气浓度，直到应用宰杀方法。在每个试验日，将鸡随机分配到三个实验组之一。采用四电极组合双侧记录脑电图。记录5分钟基线后，应用宰杀方法，并记录脑电图以及其他行为和生理反应，包括抽搐、喘气、身体运动停止和羽毛竖起，持续5分钟。利用脑电图频段（α、β、δ、θ）、中位数频率（F50）、95%频谱边缘频率（F95）和总功率（Ptot）的变化来评估农场宰杀事件的质量。在注射戊巴比妥钠后15秒内，平均频段显著下降，F50和F95平均增加，Ptot下降，提示脑死亡。此外，与MCD和CD相比，注射戊巴比妥钠后鸡停止运动的潜伏期更短（分别为22秒与115秒和136秒）。应用CD后120秒时F95显著增加，Ptot下降；在135秒时频段随之下降，171±15秒时脑电图呈等电位。MCD后与脑死亡一致的变化包括207±23秒时脑电图呈等电位，应用后300秒时一些频段显著下降。在MCD组未观察到其他显著的频谱频率变化，提示脑死亡可能在5分钟终点附近发生。在CD和MCD处理中，行为、生理和脑电图反应之间没有明显关联。数据表明，无论母鸡品种如何，戊巴比妥钠均可诱导快速死亡，且行为和生理反应最小。相比之下，使用CD和MCD导致母鸡脑死亡的起效较慢。
