Return-to-sensibility problems after penetrating captive bolt stunning of cattle in commercial beef slaughter plants

Objective-To evaluate efficacy of penetrating captive bolt stunning of cattle in commercial beef slaughter plants and identify potential causes of a return to sensibility among stunned cattle. Design-Observational study. Sample Population-21 federally inspected commercial beef slaughter plants. Procedure-In each plant, stunning of at least 100 cattle (19 large plants) or a minimum of 1 hour of production (2 small plants) was observed, and cattle were evaluated for signs of returning to sensibility on the bleed rail. Cattle with a limp, flaccid head, a lack of spontaneous blinking, and an absence of a righting reflex were considered insensible. Results-In 17 of the 21 (81%) plants, all cattle were rendered insensible before they were hoisted onto the bleed rail. The remaining 4 plants had cattle that had signs of returning to sensibility, these cattle were restunned prior to skinning or leg removal. Of 1,826 fed steers and heifers, 3 (0.16%) had signs of returning to sensibility, whereas 8 of 692 (1.2%) bulls and cows did. Return-to-sensibility problems were attributed to storage of stunner cartridges in damp locations, poor maintenance of firing pins, inexperience of the stunner operator (ie, shooting cattle too high on the forehead), misfiring of the stunner because of a dirty trigger, and stunning of cattle with thick, heavy skulls. Conclusions and Clinical Relevance-Results suggest that efficiency of captive bolt stunning of cattle in commercial slaughter plants can be safely and objectively assessed. Care should be taken to maintain stunners correctly, particularly when stunning bulls and cows with heavy skulls.