April 10, 2019

Interpretive Summary: Immune response and productivity of heifers during viral-bacterial challenge

Interpretive Summary: Effects of combined viral-bacterial challenge with or without supplementation of Saccharomyces cerevisiae boulardii strain CNCM I-1079 on immune upregulation and DMI in beef heifers.

By: Anne Wallace

Bovine respiratory disease is extremely detrimental to animal welfare and production despite vaccinations and antibiotics. Therefore, alternative therapies are desired. In this paper published in the March 2019 Journal of Animal Science, Saccharomyces cerevisiae boulardii strain CNCM I-1079, a direct-fed microbial (DFM) live yeast (LY), was evaluated for its effects on immune response and productivity of heifers during a viral-bacterial (VB) challenge.

Prior to the study period, heifers were vaccinated for Clostridial and respiratory pathogens; blood was additionally tested for Mannheimia haemolytica (MH) and bovine herpes virus-1 (BHV-1) antibodies. This study included 38 healthy, eleven-month-old Angus crossbred heifers. Feed was either supplemented with LY, or did not contain LY, and all animals were either endobronchially inoculated with VB-challenge (BHV and Mannheimia haemolytica), or a phosphate buffer solution (PBS) negative control. 

Results indicated that the innate immune response of VB-challenged heifers was increased over PBS controls—heifers challenged with VB had elevated rumen temperature (RUT), blood immune markers (e.g. neutrophils), and clinical symptoms of a respiratory tract infection (e.g. nasal lesions). There was no significant difference in dry matter feed intake (DMI), body weight,or average daily gain (ADG) in animals fed diets with or without LY. However, VB-challenged animals had reduced DMI (days 3-7) and ADG compared to negative PBS controls. Animals whose feed was supplemented with LY, however, had increased neutrophils and monocytes in their blood—indicative of an increased innate immune response. 

Overall, the results of this study suggest that Saccharomyces cerevisiae boulardii yeast may be able to alter the immune response in heifers dealing with a VB challenge. How these changes may potentially impact BRD warrants further studies.

To view the article, visit the Journal of Animal Science.