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Many small slaughter facilities use head-only electrical stunning to render swine unconscious and insensible to pain before slaughter. Head only electrical stunning is a reversible procedure that is optimally effective for approximately 15 s after stun completion. In many small North American slaughter plants, the authors have observed hoist speeds that are too slow to achieve a short enough stun-to-bleed interval to maintain insensibility through exsanguination. Unlike many European plants, there is no separate high speed hoist for pigs and exsanguination on the floor is not condoned. As a result, a 2-stage stunning method was proposed where head-only stunning for 3 s was immediately followed by application of the same stunning wand to the cardiac region of the animal for 3 s while lying in lateral recumbancy. A paired-comparison study was conducted on 89 pigs in a small slaughter facility to compare the head-only method applied for 6 s with the head/heart method. The objective was to evaluate signs of return to sensibility, stun-to-bleed time, blood lactate concentration, muscle pH, drip loss, and fresh meat color to validate the head/heart electrical stunning method for small slaughter plants. Incidence of corneal reflex was not different (P > 0.05) between head/heart (93.8%) and head only (85%) stunning. Nose twitching was more common (P < 0.05) in head only (26.5%) than head/heart (5%) stunning. Head/ heart stunning eliminated rhythmic breathing, natural blinking, eye tracking to moving objects, and righting reflex, which were all observed in head-only stunned pigs. Eye tracking to moving objects was observed in 40.8% of head-only stunned pigs. Blood lactate was not different (P > 0.05) between stunning methods (head only: 8.8 ± 0.7 mmol/L, head/heart: 7.8 ± 0.7 mmol/L). Stun-to-bleed time did not differ (P> 0.05; head only: 32 ± 1 s, head/heart: 33 ± 1 s). Mean time to loss of heartbeat with the head-only method was 121 ± 5 s. No heartbeat was observed with the head/heart method. Longissimus thoracis pH, color, and drip loss were not different (P > 0.05) between stunning methods. This study determined that the head/heart electrical stunning method reduces the incidence of signs of return to sensibility without significant effects on meat quality, plant operation speed, or blood lactate concentration. In addition, the head/heart method requires no capital investment for plants that are currently using the head-only method. [ABSTRACT FROM AUTHOR]

Captive bolt stunning is commonly used as a means of quickly and effectively rendering cattle insensible prior to slaughter. Effective stunning of cattle is partially ensured by proper placement of the device, which may be breed dependent. For Holsteins, stun placement is typically recommended 2.5 cm above common placement for other breeds. The purpose of this study was to determine if head dimensions and brain location differ between Holstein and non-Holstein breeds. This study also examined the effects of different bolt lengths on physical brain damage. It was hypothesized that head size and brain damage would not differ based on bolt length or breed. This study used a randomized, unbalanced block design, with treatment blocked by day. Experimental unit was animal, and analyses were performed using t-tests in SAS 9.4 (SAS Inst. Inc., Cary, NC). The stunner used was a Jarvis USSS-1 (Jarvis Products Corp., Middletown, CT), a penetrating, pneumatic captive bolt gun. For brain damage assessment, 292 heads were randomly sampled across 3 collection periods, with an approximately equal split between Holstein and non-Holstein breeds. Each period was assigned the control bolt (CON), medium bolt (MED), or long bolt (LON), with lengths of 15.2, 16.5, and 17.8 cm, respectively. Heads were collected, immediately measured, and chilled for splitting and damage analysis at the Colorado State University Necrology Laboratory (Colorado State University Veterinary Teaching Hospital, Fort Collins, CO). For head dimension assessment, 426 heads equally distributed between Holstein and non-Holstein breeds were sampled. Head width, poll to orbit, right orbit to poll, and left orbit to poll did not differ between breeds (P > 0.13). Head length and orbit to nose length were greater for Holsteins (P = 0.0046). Brain size, length, and width as well as skull thickness did not differ between breeds (P > 0.32). Stunning metrics included bolt entrance hole diameter, which was greatest for the LON, least for the MED, and intermediate for the CON (P < 0.0001). Bolt penetration depth was greatest for the MED (P < 0.0001). Sagittal brain damage was least for the CON, with greater damage measured on the MED and LON (P < 0.0001). Dorsal damage was least for the CON and increased for the MED and LON (P < 0.0001). The data in this study suggest that differing bolt lengths affect brain damage and that head dimensions appear to be different between breeds only in nose length, indicating that current recommendations for differing stun placement based on breed may need to be reevaluated. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the effect of captive bolt lengths on penetration hole characteristics, brain damage, and specified risk material (SRM) dispersal. Cattle were stunned with a pneumatic captive bolt stunner using: standard (15.2 cm; STRD), medium (16.5 cm; MED), or long (17.8 cm; LON) bolts. Heads (N = 293) and exsanguination blood (N = 103) were collected for analyses. Penetration hole diameter and depth differed by treatment (P ≤ 0.004); both parameters were greatest for LON (P < 0.05). Presence of damage in frontal, parietal, and occipital lobes, olfactory bulb, and collective area including the corpus callosum, fornix and thalamus were impacted by treatment (P < 0.003). Treatment did not impact SRM dispersal (P = 0.33), determined by presence of glial acidic fibrillary protein. Data suggest that bolt length affects both the extent of brain damage and the specific structures damaged but all bolt lengths are successful in causing substantial brain damage and subsequent insensibility. [ABSTRACT FROM AUTHOR]