Animal Welfare Assessment and Meat Quality through Assessment of Stress Biomarkers in Fattening Pigs with and without Visible Damage during Slaughter

Abstract

The study aimed to investigate the physiological and meat quality differences between Non-Ambulatory, Non-Injured (NANI), and without apparent abnormalities (non-NANI) pigs in a commercial slaughterhouse setting, focusing on the impact of stress and health conditions on the overall well-being and meat quality of the animals. A total of 241 surgically castrated crossbred male pigs from Southern Brazil were analyzed, with 131 non-NANI pigs and 110 NANI pigs. Infrared orbital temperature, rectal temperature, hematological parameters, and meat quality measurements were collected. Statistical analysis included ANOVA tests and principal component analysis (PCA). NANI pigs exhibited significantly higher infrared orbital temperatures and rectal temperature (p < 0.01). Hematological analysis revealed higher levels of hemoglobin, hematocrit, and red blood cells in NANI pigs (p < 0.05). White blood cell count and lactate dehydrogenase were significantly elevated in NANI pigs (p < 0.01), indicating potential infections or inflammatory responses. Meat quality parameters showed that NANI pigs had lower pH values, higher luminosity, and increased drip loss (p < 0.01), reflecting poorer water retention and potential muscle glycogen depletion. The study highlights the physiological and meat quality differences between NANI and non-NANI pigs, emphasizing the impact of stress, health conditions, and handling procedures on the animals. Blood biomarkers proved valuable in assessing physiological stress, immune response, and potential health issues in pigs, correlating with meat quality abnormalities. Utilizing these biomarkers as predictive tools can enhance animal welfare practices and contribute to improving meat quality in the swine industry.

Keywords: fatteners; physiological response; slaughter; slaughtering performance; stress.

Figure 1

Classification of the meat quality of NANI and non-NANI pigs. NANI = non-ambulatory, non-injured; non-NANI = pigs showing no apparent anomalies. Superscript * mean that treatments are significantly different (p > 0.05). PSE = pale, soft, exudative; PFN = pale, firm, and nonexudative; RSE = red, soft, exudative; RFN = red, firm, and nonexudative; DFD = dark, firm, and dry.

Figure 2

Principal component analysis with infrared orbital temperature and hematological and biochemical parameters of NANI and non-NANI pigs. PC1 = Principal Component 1; PC2 = Principal Component 2; RT = rectal temperature; HB = hemoglobin concentration; HT = hematocrit; RBC = red blood cells; MCV = mean corpuscular volume; MCH = mean corpuscular hemoglobin; MCHC = mean corpuscular hemoglobin concentration; RDW = red blood cell distribution width; WBC. = white blood cells; Seg. = segmented neutrophils; Lymph. = lymphocytes; Pl. = platelets; LDH = lactate dehydrogenase.

Figure 3

Principal component analysis with infrared orbital temperature and meat quality parameters of NANI and non-NANI pigs. PC1 = Principal Component 1; PC2 = Principal Component 2; IROT MAX = maximum infrared orbital temperature; IROT MIN = minimum infrared orbital temperature; IROT AVG = average infrared orbital temperature; RT = rectal temperature; L* = luminosity; a* = green-red component; b* = blue-yellow component; pH LT = longissimus thoracis pH; pH SEM = semimembranosus pH; WL = weight loss during cooling.