Haematological changes to assess stress arising from different methods of slaughtering in pigs

Abstract

This study aimed to investigate the blood profile and neutrophil and lymphocyte ratio (NLR) in pigs subjected to stunning and non-stunning. Forty pigs, aged between 6-8 months and weighing 80-100 kg, were used to assess haematological changes associated with different slaughter techniques and to evaluate stress levels. The samples were divided into two groups, the first group was subjected to stunning (with a captive bolt), and the other served as a non-stunning (control). Blood samples were collected from each pig using EDTA anticoagulant tubes, with 3 mL of blood collected per sample. These samples were then analyzed using an auto-haematology analyzer to measure various parameters including RBC, HB, PCV, MCV, MCH, WBC, neutrophils, lymphocytes, monocytes, and eosinophil, as well as the ratio of neutrophils and lymphocytes. The results showed that stunning pigs with a captive bolt exhibited significantly higher levels of RBC, PCV, and lymphocytes with a value of 8.144±1.66 (×106/µL); 41.5±13.62(%) and 41.805±7.82(%), compared to non-stunning pigs with a value of 7.209 ± 1.22 (×106/µL); 36.65±6.12(%); and 22.2±12.24 (%), respectively. However, stunning pigs exhibited lower WBC and neutrophils, measuring 13.825 ± 8.56 × 103/µL and 41.75±16.64(%) with captive bold, compared to non-stunning pigs with a value of 20.375±9.83 (×103/µL) and 63.30±19.04 (%) respectively. The NLR index was higher in non-stunning pigs, with a value of 2.851, compared to stunning pigs subjected to a captive bolt, with an index of 1.006. In conclusion, stunning with a captive bolt was found to reduce the stress level of pigs before slaughter, potentially leading to improvements in meat quality.