Effect of Dietary Supplementation of Capsicum Extract on Immune Responses, Blood Cell Counts, Blood Chemistry, and Oxidative Stress Markers in Lactating Dairy Cows

Abstract Text: The objective of this experiment was to investigate the effects of dietary Capsicum extract (CE) on T-cell phenotypes, phagocytotic and oxidative burst activity of neutrophils, blood cell counts, blood chemistry, and oxidative stress markers in lactating dairy cows. Eight multiparous Holstein cows (DIM, 50 ± 9.6 d; BW, 591 ± 32.6 kg), including 3 ruminally-cannulated, were used in a replicated 4 × 4 Latin square design with 25-d periods. Treatments were 0 (CON), 250, 500, and 1,000 mg CE/cow/d, in which the principal active compounds were capsaicin and dihydrocapsaicin. The CE was mixed with a small portion of the TMR and topdressed. Compared with CON, CE did not affect concentration of cluster of differentiation antigen (CD) 4 positive, CD8⁺, CD25⁺, and γδ⁺ cells. The phagocytosis and oxidative burst activity of neutrophils were also not affected by CE. Relative to CON, total white blood cells, neutrophils, and eosinophils were linearly increased (P = 0.04, 0.01, and 0.03, respectively) with CE supplementation. Treatments had no effect on lymphocytes, monocytes, and basophils. Red blood cells quadratically increased (P = 0.04) with CE. Hemoglobin was higher (P < 0.01) for CE than CON and responded quadatically to CE level of supplementation. Platelets were lower for CE than CON and linearly decreased (P = 0.04) with CE supplementation. Glucose, creatinine, albumin, and total protein in blood plasma were not affected by CE. Blood urea N was increased (P = 0.02) by CE relative to CON and blood plasma P concentration tended to be lower (P = 0.09) for CE than CON. Although there was no effect of CE on oxygen radical absorbance capacity (ORAC) and thiobarbituric acid reactive substances (TBARS), CE tended to decrease (P = 0.09) 8-isoprostane relative to CON (14.7 vs. 16.5 pg/mL, respectively). In conclusion, dietary supplementation of CE did not affect T cell phenotypes and neutrophil activities in this study. However, CE increased total white blood cells, neutrophils, and eosinophils, and tended to decrease 8-isoprostane. It is suggested that CE may facilitate cells with function in innate immunity and reduce blood oxidative stress markers in lactating dairy cows.

Keywords: capsicum extract, immune response, oxidative stress