Blood parameters as biomarkers in a Salmonella spp. disease model of weaning piglets

Abstract

Background: The weaning pig is used as an experimental model to assess the impact of diet on intestinal health. Blood parameters (BP) are considered a useful tool in humans, but there is very scarce information of such indicators in the weaning pig. The objective of the present study is to evaluate the use of different BP as indicators in an experimental model of salmonellosis.

Methodology: Seventy-two 28-day-old piglets were divided into four groups in a 2x2 factorial arrangement, with animals receiving or not a probiotic combination based on B. infantis IM1® and B. lactis BPL6 (109 colony forming units (cfu)/d) and orally challenged or not a week later with Salmonella Typhimurium (5x108 cfu). Blood samples of one animal per pen (N = 24) were taken four days post-inoculation for the evaluation of different BP using an I-stat® System and of plasmatic concentrations of zinc, iron and copper.

Principal findings: Results reported marginal deficiencies of zinc in piglets at weaning. Moreover, plasmatic zinc, copper and iron presented good correlations with weight gain (r 0.57, r -0.67, r 0.54 respectively; P < 0.01). Blood electrolytes (Na+, Cl- and K+) decreased (P < 0.01) only when the performance of the animals was seriously compromised and clinical symptoms were more apparent. Acid-base balance parameters such as HCO3-, TCO2 and BEecf significantly correlated with weight gain, but only in the challenged animals (r -0.54, r -0.55, and r -0.51, respectively; P < 0.05), suggesting metabolic acidosis depending on Salmonella infection. Glucose was affected by the challenge (P = 0.040), while Htc and Hgb increased with the challenge and decreased with the probiotic (P < 0.05). Furthermore, correlations of Glu, Htc and Hgb with weight gain were observed (P < 0.05). Overall, BP could be regarded as simple, useful indexes to assess performance and health of weaning piglets.

Fig 1. Evolution of the mean fecal scores in the different experimental groups during the post-inoculation period.

Treatments: CN (challenged + no probiotic), CP (challenged + probiotic), NN (non-challenged + no probiotic) and NP (non-challenged + probiotic) (challenged groups n = 8; non-challenged groups n = 4). Values represented are LSmeans with their standard errors. ^A Challenge: main effect of the Salmonella Typhimurium inoculation (5 x 10⁸cfu). ^B Probiotic: main effect of a daily dosage (10⁹cfu) of a combination of B. infantis IM1^® and B. lactis BPL6. ^C Days after the challenge with Salmonella.