Effects of N-carbamylglutamate and L-arginine on steroidogenesis and gene expression in bovine granulosa cells

•N-Carbamylglutamate inhibited granulosa cell estradiol and progesterone production.•L-Arginine inhibited estradiol production but did not affect progesterone production.•N-Carbamylglutamate and L-Arginine increased granulosa cell proliferation. Feeding N-carbamylglutamate (NCG) and arginine (ARG) improves reproductive measures in pigs and reduces systemic steroid levels in pregnant ewes. We hypothesized that the effects of NCG and ARG on reproduction were due to direct effects on the ovary. Thus, the objectives of this study were to investigate the effects of NCG and ARG on granulosa cell (GC) steroidogenesis, gene expression, and cell proliferation in vitro. GC were collected from small (1–5mm) bovine follicles and treated in vitro with NCG or ARG in serum-free medium for 24h to 48h. Both NCG and ARG inhibited (P