Effect of repeated ACTH-stimulation on early embryonic development and hormonal profiles in sows.

This study was conducted to evaluate the effect of adrenal stimulation by synthetic adrenocorticotrophic hormone (ACTH) on the first 2 days of pregnancy in 22 multiparous sows. The experiment was performed during the second oestrus after weaning and the sows were divided into one control (C-group) and one experiment group (E-group). To determine the time of ovulation, transrectal ultrasonographic examination was performed. E-group sows were treated repeatedly with 0.1 mg/kg bodyweight of synthetic ACTH (tetracosactide) i.v. 4-8h after ovulation and continuing every 6h, until slaughter. Blood samples were collected every second hour from about 12h before expected ovulation until slaughter and were analyzed for cortisol, prostaglandin F(2 alpha) -metabolite, and progesterone (P(4)). All sows were slaughtered approximately 48 h after ovulation and the isthmic part of the oviduct was divided into three equally long segments and flushed separately with phosphate buffered saline (PBS). The uterine horns were also flushed with PBS. The embryos of the E-group sows tended (P=0.056) to have a lower cleavage rate than the embryos of the C-group sows but there was no difference between groups in oviductal transport rate of the embryos. In the E-group, significantly (P<0.05) more sows had only embryos with <20 spermatozoa attached to the ZP compared with the C-group. The plasma concentration of cortisol was significantly higher (P<0.0001) in the E-group sows during the time of treatment while the baseline level of prostaglandin F(2 alpha) -metabolite was significantly lower. The baseline level of progesterone increased in both groups after ovulation but there was no significant difference between the groups. Repeated ACTH-stimulation (1) had no effect on the oviductal transport rate of the embryos, (2) had a negative effect on the embryo development, (3) and caused a changed endocrine profile that might have changed oviductal milieu affecting embryo development.