Characterization of Changes in Swine Blood Metabolite Concentrations from Weaning to Finishing

Abstract Measurement of blood metabolites is often performed for a variety of diagnostic and research purposes. Evidence exists in the literature describing normal references ranges, however the origin of these measures is often not clearly described as well as description of important factors such as health status, dietary nutrient levels, and management practices. As a preliminary analysis within a larger project aimed to characterize the relationship between blood biomarkers and growth performance outcomes, a total of 144 high-health offspring (DNA 241 × 600) from first litter sows were used to characterize changes in circulating blood metabolite concentrations from weaning until market. Non-fasted blood samples were collected from each pig at weaning (d 18 of life), end of the nurser period (d 70 of life), midpoint of the finisher (d 123 of life) and end of finisher (d 161 of life). Whole blood samples were analyzed for a panel of 24 metabolites, including proteins, vitamins, minerals, and blood metabolites, using iCheck Vitamin E (BioAnalyt, Teltow, DE), iSTAT Alinity (Abbott, Park, IL), and VetScan (Zoetis, Parsippany, NJ) -based rapid analysis technologies. Data were analyzed in SAS using a repeated measures model, with dam and animal ID included as random effects. The pigs were also utilized in sow, nursery, and finisher feeding trials with sow treatment, nursery treatment, finishing treatment, and each of their interactions with sampling time were included in the model as fixed effects to standardize for concurrent experimental treatments. All biomarkers demonstrated age-dependent changes. Some metabolites, such as Vitamin E exhibited a quadratic decrease (P 0.0001), reaching their lowest concentrations at the midpoint of the finisher before increasing again at the final blood collection timepoint. Hemoglobin and hematocrit exhibited a quadratic increase (P 0.001) throughout the pig’s life, with the greatest increase occurring from the midpoint of the finisher to the final blood collection event. Ionized Ca quadratically increased (P 0.001) until the end of the nursery and then decreased thereafter. Creatinine exhibited a linear increase (P 0.0001) from weaning until the last collection timepoint at the end of the finisher. These findings provide a preliminary characterization of changes in swine blood metabolites across production stages in healthy pigs. Further analysis will explore associations of metabolite concentrations with measures of productivity including growth rate.