021 Evaluation of different captive bolt lengths and breed influence upon postmortem leg activity in fed cattle

Captive bolt stunning is a widely used means across commercial beef plants to render animals insensible. After stunning, postmortem leg activity poses a safety risk for employees; hence, the objective of this study was to test captive bolt length effects on postmortem leg activity. It was hypothesized that captive bolt length and cattle breed do not influence postmortem leg activity. A total of 2,850 Holstein and non-Holstein Continental/British-bred fed cattle were sampled. The Jarvis USSS-1 (Jarvis Products Corp., Middletown, CT) penetrating pneumatic captive bolt stunner was used with 3 different bolt lengths: 15.24, 16.51, and 17.78 cm, constituting control, medium, and long treatment groups, respectively. The study was an unbalanced, randomized block design, blocked by day, and breed was recorded as Holstein or non-Holstein. The experimental unit was animal and data were analyzed within SAS 9.4 (SAS Inst., Inc., Cary, NC) using t-tests. Immediately after knocking, cameras were placed to record postmortem forelimb and hind limb kicking, the number of times each animal was stuck to be exsanguinated, and if the take away belt stopped. Immediately after stunning, cattle fall from the center track restrainer onto the take away belt to be shackled, which influences the stunning-to-exsanguination interval. There were more hind limb kicks using the long bolt (P= 0.03) compared with the medium bolt, and more Holstein hind limb kicks were observed relative to non-Holstein (P= 0.0009). Forelimb kicks were greater for medium (P< 0.0001) and long (P< 0.0001) compared with control, and more non-Holstein forelimb kicks occurred relative to Holstein (P= 0.0002). The number of take away belt stops was more for control than medium (P< 0.0001) as well as long (P< 0.0001). Take away belt stops was greater for Holstein relative to non-Holstein (P< 0.0001). Righting reflex and number of sticks did not differ regardless of treatment or breed (P> 0.23). These data show that captive bolt length and breed play a role in postmortem activity of fed cattle and that breed plays a role in take away belt stops and thus the stun-to-exsanguination interval. Further research is needed to explore the intricacies of these relationships.