The objective of this project was to determine the impact of cooling on the soft tissue thickness, cranial thickness, and cross-sectional brain area of cadaver heads from market pigs. Documenting the effect of cooling on tissue dimensions of swine heads is valuable and important for future investigations of physical stunning and euthanasia methods that use cadaver heads. Scalded and dehaired cadaver heads with intact jowls were sourced from market pigs stunned with CO2 gas. After transport to the data collection location, a penetrating captive bolt (PCB) shot (Jarvis Model PAS—Type P 0.25R Caliber Captive Bolt Pistol with Medium Rod Assembly and Blue Powder Cartridges) was applied in the frontal position. Following PCB application, each head (n = 36) underwent an UNCHILLED treatment followed by CHILLED treatment. The UNCHILLED treatment involved images collected immediately after splitting each head along the bolt path, and the CHILLED treatment involved images of the same heads after storage in a walk-in cooler for 24 h at 2 to 4°C. All measurements for each treatment were collected from images of the heads on the plane of the bolt path immediately prior to and immediately after the refrigeration treatment. Measurements were performed by two observers. Across all measurements, mean interobserver coefficient of variation was 11.3 ± 0.6%. The soft tissue caudal to the bolt path was different (P = 0.0120) between treatments (CHILLED: 6.4 ± 0.2 mm; UNCHILLED: 7.2 ± 0.2 mm). The soft tissue thickness rostral to the bolt path was different (P = 0.0378) between treatments (CHILLED: 5.5 ± 0.2 mm; UNCHILLED: 6.1 ± 0.2 mm). Cranial thickness caudal to the bolt path was not different (P = 0.8659; CHILLED: 18.1 ± 0.6 mm; UNCHILLED: 18.3 ± 0.6 mm), nor was there a significant difference (P = 0.2593) in cranial thickness rostral to the bolt path between treatments (CHILLED: 16.2 ± 0.6 mm; UNCHILLED: 15.2 ± 0.6 mm). Cross-sectional brain area did not differ (P = 0.0737; CHILLED: 3633.4 ± 44.1 mm; UNCHILLED: 3519.9 ± 44.1 mm). A correction factor of 1.12 was determined from this study for cases where estimation of UNCHILLED soft tissue thickness from CHILLED soft tissue thickness is necessary.

The objective of this study was to contrast the soft tissue thickness, cranial thickness, total tissue thickness, cross-sectional brain area, and bolt–brain contact from the common frontal application of captive bolt euthanasia with the alternative location behind the ear in cadaver swine heads. Twenty-three cadaver heads from pigs that were approximately 136 kg and 6 mo of age were collected from a regional slaughter establishment following CO2 stunning and assigned to either the FRONTAL (n = 11) or the CAUDAL TO PINNA (n = 12) application of the captive bolt. The soft tissue thickness was different (P < 0.0001) between the 2 applications (FRONTAL: 8.3 ± 3.4 mm; CAUDAL TO PINNA: 56.5 ± 3.4 mm). The cranial thickness was different (P < 0.0001) between the applications (FRONTAL: 23.4 ± 2.9 mm; CAUDAL TO PINNA: 26.5 ± 2.9 mm). There was also a difference (P < 0.0001) in the total tissue thickness between the 2 applications (FRONTAL: 31.7 ± 3.8 mm; CAUDAL TO PINNA: 73.4 ± 3.8 mm). Cross-sectional area was calculated from images collected immediately after the heads were cut along the plane of bolt travel by bandsaw and was different (P = 0.0028) between the 2 applications (FRONTAL: 25.2 ± 1.3 cm2; CAUDAL TO PINNA: 18.9 ± 1.3 cm2). Bolt–brain contact was also assessed from the images, and a difference (P = 0.0360) between the 2 applications (FRONTAL: 100 ± 10.5%; CAUDAL TO PINNA: 66.7 ± 10.5%) was identified. The results of this study suggest that the FRONTAL application may provide a bolt path with less tissue to travel through when compared with the CAUDAL TO PINNA application for pigs of the approximate age and weight of those in this study. Ultimately, the FRONTAL location may present less risk for the captive bolt euthanasia of swine at market weight at this time. Additional refinement of the CAUDAL TO PINNA procedure and modification to the captive bolt device to penetrate to a suitable depth to ensure brain damage is recommended.

The weaning period is a stressful time for beef calves because they must quickly gain independence from their dam. Gradual methods of weaning, such as when the calf is fitted with a nose flap to prevent suckling, are known to reduce the behavioral and physiological indicators of stress. Nose flaps are held in place by the nasal septum and are worn for 4 to 7 d. In the present study, the objectives were to 1) identify if a plastic nose flap worn for 7 d caused nasal injuries, (2) identify if factors like calf body weight or septum size predict injuries or flap loss, and (3) create a scoring system that could reliably score wound characteristics. Eighty-two (N = 82) Angus and Angus-Hereford crossbred beef calves were randomly assigned to ‘Flap’ or ‘No Flap’ treatments. Calves weighed 247 ± 29 kg and those with a flap had septums that were 39 ± 2 mm (mean ± SD). Images were taken of each nostril before flap insertion, on the day of removal, and 6 d after removal. Wounds were scored for the presence/absence of 3 characteristics in either nostril: damage (tissue where the flap rested was a different color than surrounding nostril), impression (edges of the wound were clearly raised or sunken), and blood. One trained observer scored a subset of photos (N = 64) twice, in a consistent manner for all 3 characteristics (damage, impression, and blood; 97%, 91%, and 100% agreement between 1st and 2nd evaluations, respectively), indicating that our system is repeatable. Thirty-two percent of calves in the Flap treatment lost their flap before the day of removal. No calves in the No Flap treatment were injured. All animals that kept their flap in for 7 d had damage and impressions in at least 1 nostril and 86% of calves had blood present immediately after nose flap removal (P ≤ 0.001 compared to No Flap) indicating that the flaps altered the nasal tissue and created open wounds. Six d after flap removal, 100% still had visible damage, 64% had impressions, and 29% had blood, indicating that while damage is longer lasting, wounds can start to repair after the flap is removed. Injuries were prevalent in all calves, thus there was no relationship between calf size (body weight or septum width) on these wounds (P ≥ 0.374). Body weight or septum size did not differ (P ≥ 0.489) between calves that kept or lost their flap. Injuries inflicted from a nose flap may counteract the previously documented benefits of this method of weaning, making it less advantageous than alternatives and raise concerns about other uses of these devices in other contexts.