Supplementing a Saccharomyces cerevisiae fermentation product modulates innate immune function and ameliorates bovine respiratory syncytial virus infection in neonatal calves Link: https://pubmed.ncbi.nlm.nih.gov/32780814/ Ultimate Message: We do have an ability to modulate immune responses to make them less damaging within the respiratory tract of our calves and potentially beyond that if you start to look outside of this study. Big 3 Take Aways: Number one, there are differences between prebiotics, probiotics, and postbiotics. Is one necessarily better than the other? Do you need one more than the other? Not necessarily, but the ability of the postbiotics to be more concentrated versus diluted in what you'll see as the prebiotic and the probiotic potentially has a bigger impact than those other two factors and is worth considering when you're considering your source or your dollar investment for your clients. Number two, innate training. We can train the immune system to respond in a less destructive way, to just respond in a more phagocytic way versus more of kind of that nuclear bomb or uncontrolled damage type of way. That's very interesting that we have the ability to do that. Number three, we have the ability to control inflammation. And that again, ties into the response we get. We have less free oxygen oxidative species going out there, less oxidative bursts occurring, less overall damage and destruction to the overall airways. Abstract: The objectives of this study were to determine the effects of oral supplementation with Saccharomyces cerevisiae fermentation products on immune function and bovine respiratory syncytial virus (BRSV) infection in preweaned dairy calves. Twenty-four Holstein × Angus, 1- to 2-d-old calves (38.46 ± 0.91 kg initial body weight [BW]) were assigned two treatment groups: control or SCFP treated, milk replacer with 1 g/d SCFP (SmartCare) and calf starter top-dressed with 5 g/d SCFP (NutriTek). The study consisted of one 31-d period. On days 19 to 21 of the supplementation period, calves were challenged via aerosol inoculation with BRSV strain 375. Calves were monitored twice daily for clinical signs, including rectal temperature, cough, nasal and ocular discharge, respiration effort, and lung auscultation. Calves were euthanized on day 10 postinfection (days 29 to 31 of the supplementation period) to evaluate gross lung pathology and pathogen load. Supplementation with SCFP did not affect BW (P = 0.762) or average daily gain (P = 0.750), percentages of circulating white blood cells (P 0.05), phagocytic (P = 0.427 for neutrophils and P = 0.460 for monocytes) or respiratory burst (P = 0.119 for neutrophils and P = 0.414 for monocytes) activity by circulating leukocytes either before or following BRSV infection, or serum cortisol concentrations (P = 0.321) after BRSV infection. Calves receiving SCFP had reduced clinical disease scores compared with control calves (P = 0.030), reduced airway neutrophil recruitment (P 0.002), reduced lung pathology (P = 0.031), and a reduced incidence of secondary bacterial infection. Calves receiving SCFP shed reduced virus compared with control calves (P = 0.049) and tended toward lower viral loads in the lungs (P = 0.051). Immune cells from the peripheral blood of SCFP-treated calves produced increased (P 0.05) quantities of interleukin (IL)-6 and tumor necrosis factor-alpha in response to toll-like receptor stimulation, while cells from the bronchoalveolar lavage (BAL) of SCFP-treated calves secreted less (P 0.05) proinflammatory cytokines in response to the same stimuli. Treatment with SCFP had no effect on virus-specific T cell responses in the blood but resulted in reduced (P = 0.045) virus-specific IL-17 secretion by T cells in the BAL. Supplementing with SCFP modulates both systemic and mucosal immune responses and may improve the outcome of an acute respiratory viral infection in preweaned dairy calves.
