Seminal plasma from bulls with divergent plane of nutrition minimally alters bovine uterine endometrial epithelial cell gene expression in vitro

Young beef bulls are often fed high-energy diets to maximize postweaning growth; however, overnutrition has been associated with decreased semen quality. Seminal plasma has been shown to prime the uterus for early pregnancy events in mammalian species; thus, alterations in this response caused by overnutrition could be detrimental or beneficial. The present study evaluated the impact of seminal plasma from bulls exposed to overnutrition on the transcriptome of endometrial epithelial cells in vitro. Yearling half-sibling beef bulls (n = 20) were stratified by age, body weight, and body condition score before being randomly assigned to one of two diets: 1) a diet formulated to elicit a target average daily gain (ADG) of 1.81 kg/d (High Gain, n = 10) or 2) a diet formulated to elicit a target ADG of 1.22 kg/d (Moderate Gain, n = 10). Seminal plasma was collected from each treatment group at three timepoints and then pooled and passed through a 22 μm sterile filter. Based on preliminary experiments, cells were randomly assigned to 1 of the 3 treatment groups: no treatment (Control), 1% seminal plasma from moderate gain bulls (Moderate Gain), or 1% seminal plasma from high gain bulls (High Gain) and cultured at 38.5 °C, 95% O2, 5% CO2 for 12 h. Experiments were conducted in duplicate per treatment, 3 times for a total of 6 experimental units per treatment group. Following the treatment period, total RNA was extracted from cells and underwent sequencing on the Illumina platform. Raw reads were mapped to the ARS-UCD1.3 Bos taurus RefSeq transcriptome, then converted to gene-level counts. The quasi-likelihood negative binomial generalized log-linear model (glmOL) from edgeR was used to test for significantly differentially expressed genes (DEG) at Benjamin-Hochberg adjusted (B.H. adj) P ≤ 0.05. There were 7,905 DEG (Padj ≤ 0.05) in bEND cells treated with seminal plasma from High Gain bulls compared with the Control. There were 8,933 (Padj ≤ 0.05) DEG in bEND cells treated with seminal plasma from Moderate Gain bulls compared with Control. There were 28 DEG (Padj ≤ 0.05) in bEND cells treated with seminal plasma from High Gain compared with Moderate Gain bulls. Metabolic pathways were depleted in each of these comparisons. In conclusion, seminal plasma alters the bEND cell transcriptome; however, the plane of nutrition had minimal effects.