Author ORCID Identifier

https://orcid.org/0000-0001-6409-1878

Semester

Spring

Date of Graduation

2024

Document Type

Dissertation

Degree Type

PhD

College

Davis College of Agriculture, Natural Resources and Design

Department

Animal and Nutritional Sciences

Committee Chair

Scott Bowdridge

Committee Member

Scott Greiner

Committee Member

Ibukun Ogunade

Committee Member

Jianbo Yao

Committee Member

Eric Kelley

Abstract

Our understanding of the complex connection between selection for parasite resistance and the overall health outcomes in livestock is unclear. This study investigates the impact of post-weaning fecal egg count (PFEC) estimated breeding values (EBV) on health outcomes and immune responses in Katahdin sheep. Selection for PFEC, favoring Low-PFEC lambs, not only affects survivability to weaning but also suggests broader implications for immunity beyond parasite resistance. The effect of PFEC EBV on antibody production in response to vaccination against Clostridium perfringens type C&D and tetanus toxoid (CD&T) revealed a stepwise decrease in immunoglobin (IgG) from Low-PFEC to High-PFEC groups upon booster vaccination (2246 µg/mL, 2103 µg/mL, 1431 µg/mL; P < 0.0001). Additionally, ewes with Low-PFEC EBV were found to produce colostrum with significantly higher IgG concentrations across lactation stages (631 ng/mL vs 222 ng/mL; P < 0.0001). This difference in IgG concentration was most notable in colostrum (937 ng/mL for Low-PFEC vs. 319 ng/mL for High-PFEC; P < 0.0001). Comparisons with St. Croix (STC) and Suffolk (SUF) sheep reveal Katahdin sheep's distinct physiological responses to lipopolysaccharide (LPS) challenge, with HiKAT sheep exhibiting heightened eosinophil counts, elevated haptoglobin levels, and greater hemolysis compared to LoKAT sheep. The study provides valuable insights into the impact of PFEC EBV on health outcomes, colostrum components, and immune responses of Katahdin sheep, offering avenues for improving animal welfare and disease resistance strategies in small ruminants.

Download

Share

COinS