The influence of dietary supplementation with the leucine metabolite β-hydroxy-β-methylbutyrate (HMB) on chemotaxis, phagocytosis and respiratory burst of peripheral blood granulocytes and monocytes in calves
Abstract Background A healthy immune system plays a particularly important role in newborns, including in calves that are far more susceptible to infections (viral, bacterial and other) than adult individuals. Therefore the objective of this study was to evaluate the effect of HMB on the chemotactic activity (MIGRATEST® kit), phagocytic activity (PHAGOTEST® kit) and respiratory burst (BURSTTEST® kit) of peripheral blood granulocytes and monocytes in calves by flow cytometry. Results An analysis of granulocyte and monocyte chemotactic activity and phagocytic activity revealed significantly higher levels of phagocytic activity in calves administered HMB than in the control group, expressed in terms of the percentage of phagocytising cells and mean fluorescence intensity (MFI). HMB also had a positive effect on the oxidative metabolism of both granulocytes and monocytes after stimulation with Escherichia coli bacteria and with PMA (4-phorbol-12-β-myristate-13-acetate), expressed in terms of the percentage of oxidative metabolism and MFI. Conclusion HMB stimulates non-specific cell-mediated immunity, which is a very important consideration in newborn calves that are exposed to adverse environmental factors in the first weeks of their life. The supplementation of animal diets with HMB for both preventive and therapeutic purposes can also reduce the use of antibiotics in animal production.