First report on whole saliva profiling of Landlly pigs for stress, inflammation, immunity, and systemic homeostasis appraisal: a pilot study

Abstract

Given the stressful nature of blood collection, it is ideal to use saliva as a source of biomarkers that can reveal information about the health of pigs. Nevertheless, no research on the characterization of salivary analytes has been undertaken for Landlly pigs. In this study, the viability of two saliva sampling procedures was tested and a sialochemistry panel was developed. A total of 30 Landlly (Landrace x Ghurrah) pigs (15 males, 15 females) in their growing phase (8-10 weeks old) were chosen to obtain the normal reference ranges of 13 salivary analytes, specifically those related to stress (cortisol, α-amylase), inflammation (diamine oxidase, DAO; calprotectin, CALP), immune status (IgA, Cu, Zn) and systemic homeostasis (glucose, total protein, Na, K, Mg, Fe). The 'cotton rope method' allowed the pigs to gnaw on a hanging cotton rope for half an hour while the 'cotton swab method' included swabbing a piece of cotton (5 cm × 5 cm) inside the pigs' mouths for five minutes. Saliva was then removed by squeezing the wet materials and centrifugation. The cotton swab method achieved the best combination of reduced sampling time and low contamination. The overall mean salivary values of cortisol, α-amylase, DAO, CALP, IgA, Cu and Zn were 40.01 ng/ml, 2086.60 IU/L, 26.76 ng/ml, 0.63 ng/ml, 116.82 ng/ml, 123.33 µg/dl and 49.43 µg/dl, respectively. Moreover, the mean salivary values were 1.71 mg/dl, 0.89 g/dl, 95.74 mmol/l, 8.94 mmol/l, 0.41 mmol/l, and 5.33 μg/dl for glucose, TP, Na, K, Mg, and Fe, respectively. All salivary analytes exhibited a positive correlation with their serum equivalents, except for K and Fe. These preliminary findings illustrate that the cotton rope method works well for pooled saliva sampling while for individual saliva samples, the cotton swab approach is appropriate. Salivary analytics has a high potential for usage in farm settings as a quick, easy, affordable, and non-invasive diagnostic method for Landlly pigs.

Keywords: CALP; Cotton rope method; Cotton swab method; DAO; Non-invasive; Sialochemistry.