Degree Type

Thesis

Date of Award

2015

Degree Name

Master of Science

Department

Animal Science

Major

Nutritional Sciences

First Advisor

Judith R. Stabel

Second Advisor

Donald C. Beitz

Abstract

Neonatal calves are immune-suppressed and susceptible to infection by Mycobacterium avium, subsp. paratuberculosis (MAP). Dietary colostrum and fat-soluble vitamins were hypothesized to enable positive regulation of microbial interactions through immunity. Thus, thirty Holstein calves were randomly assigned to experimental treatments: 1) colostrum deprived (CD), no vitamins; 2) colostrum replacer (CR), no vitamins; 3) CR, vitamin A; 4) CR, vitamin D3; 5) CR, vitamin E; 6) CR, vitamins A, D3, E, and were fed pasteurized whole milk (PWM) for 14 d. Calves were orally inoculated with 108 cfu of Mycobacterium avium subsp. paratuberculosis (MAP) per dose on d 1 and 3 of age. Blood was collected at birth and on d 1, 7, and 14, and feces were collected on d 7. Calves were euthanized on d 14 for collection of intestinal contents, mucosal scrapings, and tissues. Serum was assayed for immunoglobulin G1, inflammatory acute phase proteins, and metabolites of vitamins A, D3, and E, and peripheral and lymphoid mononuclear leukocytes were characterized by flow cytometry. The immune status and health of calves was related to intestinal microbial community structure.

Non-supplemented calves fed PWM were vitamin D and E deficient, and supplementation with colostrum and vitamins D3 and E decreased the likelihood of scours. Colostrum-deprived calves failed to passively acquire IgG1 and haptoglobin and exhibited decreased peripheral abundance of γδ T cells, which indicated TH1-biased immunity. TH1-like peripheral responses to PHA were observed in vitro, but TH2-like lymphoid responses to MAP in vitro included γδ T cell proliferation. Shedding of MAP was observed at d 7, and MAP colonized the distal small intestine in low abundance. Nutritional treatments affected microbial community structure in a manner consistent with clinical observations of health. Microbial communities of cecum and colon in CD calves were richer than in CR calves, and mucosal communities in the spiral colon of CD calves exhibited dysbiosis by harboring increased Proteobacteria and decreased Bacteroidetes. Disparity between lumen and mucosal microbial communities was related to decreased health. Thus, aberrant regulation of immunity upstream of the large intestine may affect MAP infection and potentiate opportunism in the cecum and colon.

Copyright Owner

Lucas Adam Krueger

Language

en

File Format

application/pdf

File Size

121 pages

Share

COinS