Hamilton Emma M, Vogel Kurt D, Kirk Ashlynn A, Rossi Michael, Anderson Karly N
Department of Animal and Food Science, University of Wisconsin - River Falls, River Falls, WI 54022, USA.
Humane Handling Institute, University of Wisconsin - River Falls, River Falls, WI 54022, USA.
Transl Anim Sci. 2024 Dec 5;8:txae170. doi: 10.1093/tas/txae170. eCollection 2024.
Yaks are a domesticated species utilized for meat, fiber, and transportation in many countries. In the United States, yak meat is growing in popularity due to its classification as a "healthy" meat. Penetrating captive bolt (PCB) is an approved method of preslaughter stunning and euthanasia for cattle. At the time of our study, peer-reviewed literature or industry guidelines for PCB stunning or euthanasia did not appear to exist for yaks. This study aimed to identify and describe an ideal placement based on the location of the thalamus, part of the brain that is important for sensibility, and to describe the tissue depths at this placement. To do this, 10 hide-on cadaver heads from yaks were sourced from a population of 30 yaks aged 24 to 48 mo, which had a mean hot carcass weight of 180.1 ± 52.0 kg (±SD). Source animals were stunned in a frontal location with a handheld PCB during normal slaughter procedures at the collaborating slaughter establishment. Cadaver heads were stored in a walk-in freezer for 96 d before head processing. Head weight, total head length, horn tip spread, and horn base circumference were measured. Heads were split down the midline using a band saw. Heads were imaged and tissue thicknesses of the exposed surface of each head were measured. Thalamic depth and measurements to describe the location of the thalamus relative to external head anatomy were recorded from these images. Results are reported as mean ± SD. On average, the total length of the head from the poll to the nose was 37.74 ± 2.83 cm. The center of the thalamus was located 11.86 ± 1.32 cm below the poll: 23.88 ± 1.56% down the frontal plane of the head. The exposed diameter of the thalamus on the frontal plane of the head was 3.43 ± 0.31%. Thus, an ideal PCB placement for yaks is located approximately 25% of the way down the frontal plane of the face of the animal. Tissue depth measurements are reported as mean ± SD followed by a 97.5% one-sided upper reference limit (URL). Soft tissue thickness was 16.03 ± 3.26 mm (URL: 23.77 mm), cranial thickness was 30.69 ± 4.34 mm (URL: 40.97 mm), and total tissue thickness was 46.71 ± 7.15 mm (URL: 63.68 mm). Thalamic depth was 92.22 ± 11.60 mm (URL: 119.74 mm). These results show that an ideal PCB placement for yaks is located at 23.88 ± 1.56% of the distance from the poll to the nose down the frontal plane of the head and a penetration depth of 92.22 ± 11.60 mm is required to reach the thalamus.
牦牛是一种被驯化的物种，在许多国家被用于获取肉类、纤维以及作为运输工具。在美国，牦牛肉因其被归类为“健康”肉类而越来越受欢迎。穿透式 captive bolt（PCB）是一种被批准用于牛的宰前致昏和安乐死的方法。在我们进行研究时，似乎不存在针对牦牛的关于PCB致昏或安乐死的同行评审文献或行业指南。本研究旨在根据丘脑的位置确定并描述理想的穿刺位置，丘脑是大脑中对感觉很重要的一部分，并描述该位置的组织深度。为此，从30头年龄在24至48个月的牦牛群体中获取了10个带皮牦牛尸体头部，这些牦牛的平均热胴体重为180.1 ± 52.0千克（±标准差）。在合作屠宰场的正常屠宰过程中，用手持式PCB在动物正面位置对来源动物进行致昏。尸体头部在步入式冷藏库中储存96天，然后进行头部处理。测量了头部重量、头部总长度、角尖间距和角基部周长。使用带锯将头部沿中线劈开。对头部进行成像，并测量每个头部暴露表面的组织厚度。从这些图像中记录丘脑深度以及描述丘脑相对于头部外部解剖结构位置的测量值。结果以平均值 ± 标准差报告。平均而言，从头顶到鼻子的头部总长度为37.74 ± 2.83厘米。丘脑中心位于头顶下方11.86 ± 1.32厘米处：在头部额平面向下23.88 ± 1.56%处。丘脑在头部额平面上的暴露直径为3.43 ± 0.31%。因此，牦牛理想的PCB穿刺位置大约在动物面部额平面向下25%处。组织深度测量值报告为平均值 ± 标准差，随后是97.5%的单侧上参考限值（URL）。软组织厚度为16.03 ± 3.26毫米（URL：23.77毫米），颅骨厚度为30.69 ± 4.34毫米（URL：40.97毫米），总组织厚度为46.71 ± 7.15毫米（URL：63.68毫米）。丘脑深度为92.22 ± 11.60毫米（URL：119.74毫米）。这些结果表明，牦牛理想的PCB穿刺位置位于从头顶到鼻子的头部额平面距离的23.88 ± 1.56%处，到达丘脑需要92.22 ± 11.60毫米的穿刺深度。
