Semester

Summer

Date of Graduation

2014

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Animal and Nutritional Sciences

Committee Chair

Dr. Robert Dailey

Committee Co-Chair

Dr. Scott Bowdridge

Committee Member

Dr. Ida Holaskova

Abstract

Early pregnant ewes, 5 or 6 day post coitus (dpc) were used as a model to study early embryonic loss via gram-negative bacterial infections, such as mastitis. Ewes 5/6 dpc were injected with a gram-negative bacteria cell wall component, lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNF-&agr;), to induce an innate immune system acute phase response (APR). The induction of the APR and its reactant molecules, such as TNF-&agr; and acute phase proteins (APP), haptoglobin (Hp) and serum amyloid A (SAA), were initiated to study their effects on embryonic loss. In addition, ewes were also injected with LPS plus dexamethasone (Dex) to study its effects on indirectly altering embryonic loss through toll-like receptor 4 (TLR4). Thirty-eight Dorset x Texel ewes were synchronized for estrus and bred by fertile rams. On 5 or 6 dpc, ewes were assigned to one of four treatment groups per pen and received via the jugular vein either 2.5 mL of 0.1% BSA/PBS (controls, n=9), 2.5 mL of 2.5 &mgr;g/kg of LPS (n=9), 5 mL of 1 &mgr;g/kg of TNF-&agr; (n=10) in two bolus injections given thirty minutes apart, or 2.5 mL of solution containing 2.5&mgr;g/kg of LPS after having received 3.5 mL of solution containing 0.14 mg/kg BW im dexamethasone (Dex, n=10) at -12 and 0 hours. Plasma was collected from the jugular vein before challenge, followed by post challenge samples every 30 minutes until 3 hours and every hour until 12 hours, and once at 24, 36, and 48 hours. In addition, behavioral changes and rectal temperature were also documented before challenge injections followed by every hour for 12 hours post challenge, and processed soon after collection for total white blood cell counts, and plasma was stored at -80°C. A white blood cell differentiation was determined by staining and counting one hundred cells classified among monocyte, lymphocyte, eosinophil, neutrophil, or basophil cell types. Assays were conducted for APR reactants, TNF-&agr;, SAA, Hp. Jugular samples were collected in EDTA treated tubes on days 9 or 10 and 25 or 26 pc for determination of concentrations of progesterone (P4) for evaluation of luteal function. At day 25 or 26 pc, detection for pregnancy was examined. Intoxication of day 5 or 6 pregnant ewes treated with LPS, TNF-&agr;, or LPS+Dex did not differ in pregnancy status among treatment groups (p=0.298) and more control ewes plus ewes treated with TNF-&agr; tended to remain pregnant than ewes treated with LPS or LPS+Dex (p=0.05). Total white blood cell count differed by treatment (p<0.0001), hour (p<0.001), and treatment by hour (p<0.0001). There was an effect of treatment on lymphocytes (p<0.0001) and monocytes (p=0.0103). There was an effect of hour on lymphocytes (p<0.0001), neutrophils (p<0.0001), and monocytes (p<0.0001). There was an effect of treatment by hour on neutrophils (p=0.0047). There was no difference in Hp concentration by treatment (p=0.0859), hour (p=0.4317), and treatment by hour (p=0.0996). There was a difference in SAA concentration by treatment (p<0.001), hour (p<0.001), and treatment by hour (p<0.001). The inflammatory response and APR was elicited via treatment with LPS. Although LPS treatment affected pregnancy, treatment with TNF-&agr; did not. Dexamethasone did attenuate the inflammatory response but did not increase pregnancy outcome.

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