Quantification of cooling effects on basic tissue measurements and exposed cross-sectional brain area of cadaver heads from Holstein cows > 30 mo of age.

Penetrating captive bolt (PCB) is the primary method of preslaughter stunning for cattle and is also used for on-farm euthanasia. The objective of this study was to quantify the impact of cooling on the soft tissue thickness, cranial thickness, total tissue thickness, and cross-sectional brain area of cadaver heads collected from mature (> 30 mo of age) dairy cows following the application of a PCB stun in a frontal placement. Hide-on cadaver heads were obtained from culled dairy cows ( N  = 37) stunned in a frontal location using a handheld PCB device (Jarvis Model PAS-Type C 0.25R Caliber Captive Bolt, Long Bolt) at a commercial slaughter establishment. Following transport to the University of Wisconsin-River Falls, heads were split at midline along the bolt path by a bandsaw and then underwent FRESH, CHILL24, CHILL48, and CHILL72 refrigeration treatments. The FRESH treatment involved images collected immediately after splitting each head, the CHILL24 treatment involved images collected after 24 h of refrigeration, the CHIL48 treatment involved images collected after 48 h of refrigeration, and the CHILL72 treatment involved images collected after 72 h of refrigeration. Measurements of soft tissue thickness, cranial thickness, total tissue thickness, and cross-sectional brain area were recorded for each refrigeration treatment. Soft tissue thickness did not differ caudal to ( P  = 0.3751) or rostral to ( P  = 0.2555) the bolt path. Cranial thickness did not differ caudal to ( P  = 0.9281) or rostral to ( P  = 0.9051) the bolt path. Total tissue thickness did not differ caudal to ( P  = 0.9225; FRESH: 24.77 mm, CHILL24: 23.93 mm, CHILL48: 24.27 mm, CHILL72: 42.30, SE: 0.86) or rostral to ( P  = 0.8931; FRESH: 24.09 mm, CHILL24: 23.99, CHILL48: 24.26, CHILL72: 24.43 mm, SE: 0.79 mm) the bolt path. Cross-sectional brain area was not different ( P  = 0.0971) between refrigeration treatments (FRESH: 9,829.65 ± 163.87 mm 2 , CHILL24: 10,012.00 ± 163.87 mm 2 , CHILL48: 9,672.43 ± 163.87 mm 2 , CHILL72: 10,235.00 ± 166.34 mm 2 ). This study demonstrated that FRESH tissue parameters can be determined from cattle cadaver heads refrigerated for 24, 48, or 72 h.