Introduction: Periconception dietary protein can affect fertility in cattle. This study investigated the effect of dietary crude protein intervention on gene expression in granulosa cells, metabolite concentrations in follicular fluid and serum anti-Müllerian hormone (AMH) concentrations.
Methods: Non-pregnant Angus cross heifers (n=320) were group fed an isocalorific low (LP 10%) or high (HP 14%) crude protein diet for >60 days prior to slaughter. Serum was prepared from whole blood collected at exsanguination. Ovaries were collected and antral follicle count (AFC) recorded. Follicular fluid and granulosa cells were collected from healthy medium-sized follicles (49 mm). Serum AMH concentrations were measured by ELISA. Metabolite concentrations were measured using a Randox RX-IMOLA autoanalyser. RNA was extracted from granulosa cells (GC). Next-generation sequencing of GC was completed using the Illumina platform and differential genes identified using theTuxedo bioinformatics pipeline.
Results and discussion: AFC was positively correlated with circulating AMH concentrations, with increased AMH concentrations in the LP diet (P<0.05). Albumin concentrations were elevated in the follicular fluid of the HP treatment (P<0.05), however urea concentrations were lower (P<0.01). Gene expression analysis of GC identified 232 differentially expressed genes (>twofold change, P<0.05) with a more stringent analysis revealing 12 genes down-regulated and 26 genes up-regulated in the HP treatment (P<0.05). Gene ontology (GO) analysis showed that genes were enriched in GO terms including response to external stimulus, proteinaceous extracellular matrix and extracellular matrix structural. These genes are associated with the AP-1 transcription factor network (regulation of cell proliferation and differentiation) and focal adhesion pathways (cell migration and signal carriers). These pathways included genes such as STAR and IGFBP5.
In conclusion, periconceptional dietary protein was observed to affect AFC and was associated with altered GC gene expression and follicular fluid metabolites.
Funded by AHDB, BBSRC and School of Veterinary Medicine and Science, University of Nottingham.
11 Jul 2016 - 11 Jul 2016