Date of Graduation

5-2015

Document Type

Thesis

Degree Name

Bachelor of Science in Agricultural, Food and Life Sciences

Degree Level

Undergraduate

Department

Animal Science

Advisor

Rosendrans, Charles F

Reader

Powell, Jeremy G

Second Reader

Coffey, Kenneth P

Abstract

Research has shown that immune cells increased from an immune response, and endocrine concentrations directly affect sperm characteristics (Jones and Mann, 1976; Hansson et al., 1989; Grattan et al., 2007). Previous findings show a negative relationship between leukocytes and sperm function (Jones and Mann, 1976) and prolactin and fertility (Grattan et al., 2007). On the other hand, research has shown a positive relationship between insulin-like growth factor (IGF) and sperm characteristics (Hansson et al., 1989). The objective of this study is to identify biomarkers for yearling bull sperm associated with endocrine response and activation of the immune system. Seventeen Brahman-influenced bulls (mean age 1.1 ±􏰀0.1 yr; BW 478 ±􏰀38 kg) were administered lipopolysaccharide (LPS) (Salmonella typhimirium 0.7 ug/kg of body weight) intraperitoneally. Blood was collected using EDTA vacuum tubes and serum separator tubes 0, 3, 6, 9, and 24 hours after LPS injection. The blood was analyzed for differential cell count on a Cell-Dyn 3500 (Abbott Diagnostics, Abbott Park, IL). Phase Haptoglobin Assay from Tridelta Development Ltd (Kit # TP 801) was used to determine Haptoglobin concentration. Concentration of the hormones prolactin, testosterone, insulin-like growth factor (IGF), and cortisol were quantified using validated radioimmunoassays (Hallford, New Mexico University). Semen was collected using electroejaculation with an Electroejac IV (Ideal Instruments/Neogen Corp., Lansing, MI) every month for five months. Sperm was analyzed for motility and morphology characteristics listed in Table 1 using Animal Motility Software, version 12.1, in 10 different fields to analyze sperm motility. An eosin-nigrosin-based live-dead stain (Jorvet Stain, Jorgensen Laboratories, Loveland, CO) was used to fix and evaluate sperm for morphology. Data was then analyzed using SAS procedures (SAS Inst., Inc., Cary, NC). Time was treated as a repeated measure and bull was the subject in the analysis of variance. Stepwise regression was used to predict sperm characteristics. Endocrine responses to stress and immune response had an effect on sperm characteristics. At weaning, certain endocrine levels and sperm characteristics were correlated. Progressive, rapid, live, dead, and live % were correlated (r > 0.51; P < 0.05) with the IGF- 1/cortisol ratio (IC). Number of sperm was correlated (r > 0.65; P < 0.01) with the IGF- 1/prolactin ratio (IP). Medium speed was correlated (r > 0.50; P < 0.05) with the cortisol/testosterone ratio (CT). Number of sperm was negatively correlated with prolactin (r < - 0.55; P < 0.05) and the prolactin/cortisol ratio (PC) (r < -0.53; P < 0.05). When the immune challenge through LPS was administered, the immune response had an effect on sperm characteristics. Slow speed and area of sperm heads were correlated with total white blood cell count (WBC) (r > 0.50; P < 0.05). Slow speed was also correlated with neutrophil concentrations (r > 0.58; P < 0.05). Number of sperm was correlated (r > 0.51; P < 0.05) with mean cell hemoglobin concentration (MCHC). Straightness was negatively correlated (r < -0.62; P < 0.01) with WBC and neutrophils. Linearity was negatively correlated (r < -0.53; P < 0.05) with WBC and lymphocytes. Straightness was also negatively correlated (r < -0.55; P < 0.05) with lymphocytes. Using regression analysis we predicted what caused the variance for number of sperm, progressive, and path velocity (VAP). The following relationships were determined: number of sperm = 172.43 + 12.8 (IGF/prolactin), r2 = .43; progressive sperm = -1469.6 + 1.63 (IGF/cortisol) + 14.41 (average temperature during immune challenge), r2 = .43; VAP = -337.52 + 0.846 (age) - 0.41 (IGF, ng/mL) + 8.39 (cortisol, ng/mL) + 13.1 (IGF/cortisol) + 3.29 (lymphocyte number x 1000), r2 = .84. This study showed that endocrine response to stress and activation of the immune system caused differences in number of sperm, progressive sperm, amount of rapid, medium, and slow sperm, percentage of live and dead sperm, straightness and linearity of sperm, and area of sperm heads.

Keywords

endocrine system, cattle industry, immune system, bull sperm

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