Assessment of time to death, brain tissue damage and clinical signs of consciousness in mature Jersey x Holstein cattle receiving a secondary penetrating captive bolt gunshot at the poll or frontal sinus locations

Abstract

Providing cattle with a good death is an ethical imperative for the dairy industry. When using a penetrating captive bolt gun (PCBG), a secondary (adjunctive) method is currently recommended. Some farms prefer to apply the secondary shot in the poll location whereas others prefer the frontal-sinus location. Unfortunately, little is known about the efficacy of these alternative secondary shot locations. The purpose of this study was to compare clinical signs of consciousness and time to death for 2 different secondary PCBG shot locations in mature Jersey x Holstein cross dairy cattle. Data was collected contemporaneously at 6 dairy operations located in the Midwest U.S. After receiving the first PCBG shot in the frontal-sinus location, cattle requiring euthanasia (n = 46) were randomly assigned to receive a secondary PCBG shot in either the poll (Frontal- Poll) or the frontal-sinus location (Frontal-Frontal) and continuously monitored for clinical signs of consciousness (corneal and palpebral reflex, rhythmic breathing, threat response, etc.) and heartbeat. Signs of consciousness were rarely observed immediately following the first frontal-sinus shot. The median time period when the last heartbeat was heard (7-8 min) did not differ between groups (P = 0.253) nor did gross brain trauma scores (P = 0.247). We conclude the location of the secondary PCBG shot (frontal vs poll) does not seem to impact time to death or gross brain trauma scores. These findings confirm results of previous research involving younger cattle and suggest additional research is needed to better understand the effect of different PCBG locations.