Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis


Agriculture, Food and Environment


Animal and Food Sciences

First Advisor

Dr. Phillip J. Bridges


Selenium (Se) is an important trace mineral in the diet of cattle. Our objective was to determine whether the form of supplemental Se fed to the dam would affect the expression of genes regulating steroidogenesis in the newborn testis. Twenty-four Angus-cross cows were assigned randomly (n=8) to individual ad libitum access of a mineral mix containing 35 ppm of Se supplied as sodium selenite (inorganic, ISe; Prince Se), Sel-Plex (organic, OSe; Sel-Plex, Alltech) or a 50/50 mix of ISe/OSe (MIX) 4 months prior to breeding and throughout gestation. All male calves were castrated within 2 days of birth and total testis RNA was subjected to microarray analysis using the Affymetrix Bovine 1.0 ST array. Ingenuity Pathway Analysis of differentially expressed genes, separated by one-way ANOVA (p<0.05) and a post-hoc LSD test, identified eight mRNAs associated with steroidogenesis. Specifically, mRNAs involved in the conversion of testosterone to estradiol were increased in the testis of OSe-supplemented when compared to ISe-supplemented animals, and mRNAs encoding genes regulating the conversion of androstenedione to testosterone or androstenedione to estradiol were decreased in the testis of MIX-supplemented when compared to ISe-supplemented cows.Expression in the neonate may equate to differences in fertility in the adult animal.