Short communication: Salivary haptoglobin and chromogranin A as non-invasive markers during restraint stress in pigs.

The objective of present study was to investigate changes in salivary components during restraint to identify potential markers of stress. Pigs were subjected to a nasal snare stress (Experiment 1) or an immobilization stress (Experiment 2) by being enclosed in a steel cage. Saliva was collected before, during and after the stress, respectively. Salivary cortisol, serum amyloid A (SAA), haptoglobin (HP), chromogranin A (CgA), amylase, K+, Ca2+ and lactoferrin content were detected. The results showed that in Experiment 1, HP and CgA content increased significantly at 10min during the restraint (P<0.05, P<0.05), in agreement with the significantly increased cortisol and SAA levels (P<0.01, P<0.05), while amylase, K+ and lactoferrin concentrations did not significantly change. In Experiment 2, salivary HP and CgA concentrations also changed significantly during the restraint (P<0.01, P<0.01), yet cortisol, SAA, amylase, K+ and lactoferrin levels did not show obvious change. The results confirmed that salivary HP and CgA content may be useful candidate biomarkers to monitor the physical state in pigs during stress.