Pre-weaning plane of nutrition and Mannheimia haemolytica dose influence inflammatory responses to a bovine herpesvirus-1 and Mannheimia haemolytica challenge in post-weaning Holstein calves

Authors: SHARON, KATE - Texas Tech University; LIANG, YU - Texas Tech University; Sanchez, Nicole; Carroll, Jeffery - Jeff Carroll; Broadway, Paul; DAVIS, EMILY - Texas Tech University; BALLOU, MICHAEL - Texas Tech University

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2019
Publication Date: 10/1/2019
Citation: Sharon, K.P., Liang, Y., Sanchez, N.C., Carroll, J.A., Broadway, P.R., Davis, E.M., Ballou, M.A. 2019. Pre-weaning plane of nutrition and Mannheimia haemolytica dose influence inflammatory responses to a bovine herpesvirus-1 and Mannheimia haemolytica challenge in post-weaning Holstein calves. Journal of Dairy Science. 102(10):9082-9096. https://doi.org/10.3168/jds.2018-15997.
DOI: https://doi.org/10.3168/jds.2018-15997

Interpretive Summary: A common practice in the dairy industry is to restrict the quantity of milk solids fed to dairy calves to accelerate calf starter consumption and decrease the age of weaning. Unfortunately, many dairy producers have adopted this management practice without understanding the long-term impacts of restricting milk solids in early life. Data demonstrates that this may have negative effects on immunity, and impaired immunity during the pre-weaning period can have significant negative consequences on growth and productivity. A study was conducted with researchers from Texas Tech University and the USDA-ARS Livestock Issues Research Unit to determine the effect of previous plane of milk replacer nutrition on the inflammatory responses to a combined viral-bacterial respiratory disease challenge, and whether the dose of the bacteria used in the challenge would influence the responses. Claves were fed either a low or high plane of milk replacer nutrition prior to weaning. A month after weaning, calves were challenged with a viral respiratory pathogen (bovine herpes virus-1) and three days later challenged with three different doses of a main bacterial respiratory pathogen (Mannheimia haemolytica). Data from this study demonstrate that feeding calves a low plane of milk replacer nutrition prior to weaning had significant negative consequences on immune function. Specifically, calves fed the low plane of milk replacer nutrition had reduced survival after the challenge and impaired disease resistance. Additionally, it appeared that the greater doses of bacteria in the challenge model were better for the study of clinical disease, while the lower dose was more suitable to study disease resistance. Overall, the lower plane of milk replacer nutrition may have impaired or delayed the adaptive immune response, resulting in an altered innate immune response. These data will be of interest to dairy calf producers, as well as scientists in the field of immunology and dairy calf production.

Technical Abstract: The objectives were to determine whether previous plane of milk replacer nutrition (PON) and M. haemolytica (MH) dose influenced inflammatory responses to a viral-bacterial respiratory challenge. Holstein calves (1 d of age; n=30) were assigned to treatments in a 2 x 3 factorial with pre-weaning PON and MH dose as main effects (n=5/treatment). Calves were fed either a low (LPN; n=15) or a high PON (HPN; n=15) from birth through weaning. Calves fed the LPN were fed 436g DM/d of milk replacer until weaning, and HPN calves were fed 797g DM/d of milk replacer from 1 to 10 d and 1080g DM/d from 11 d until weaning. Calf starter and water were offered ad libitum. Calves were step-down weaned beginning at 54 d and moved into an enclosed barn at 70 d. Indwelling rectal temperature (RT) recording devices and jugular catheters were inserted at 80 d. Calves were challenged with 1.5x108 PFU/mL/nostril of bovine herpesvirus-1 (BHV-1) at 81 d and with either 106, 107, or 108 CFU of MH at 84 d. Blood samples were collected at varying intervals respective to BHV-1 and MH challenges. Four LPN calves either died or were euthanized soon after the 144 h observation period, whereas all HPN calves survived the entire observation period. As dosage of MH administered increased, the acute and systemic inflammatory responses increased in challenged calves. The greater doses resulted in increased neutrophils, leukocytes, and haptoglobin concentrations in infected calves. The data from the current study suggest that the greatest dose, 108 CFU, reflects weaned calves’ acute disease response, while the lower dose of 106 CFU may be a more appropriate model to study infection and disease resistance in weaned dairy calves. The impacts of PON on disease resistance as well as response show the reduced PON had impaired disease resistance. Calves fed a LPN had increased peripheral neutrophil and leukocyte counts, serum IL-6, and serum haptoglobin concentrations post BHV-1 challenge. Additionally, following the MH challenge LPN calves had increased peripheral neutrophil counts, a greater neutrophil:lymphocyte ratio, and numerically greater serum haptoglobin concentrations. There was also an increase in mortality in the LPN treatment. Calves previously fed a HPN had increased antibody titers 9 d post BHV-1 challenge compared to LPN calves. These data demonstrate that greater doses of MH increase the acute inflammatory response and prolong inflammation and that calves previously fed a LPN responded more severely to the combined viral-bacterial respiratory challenge.