Effect of systemic cortisol on pregnancy rate in repeat breeding cows during early pregnancy

The effect of systemic cortisol on pregnancy rate during early pregnancy in repeat breeding cows was estimated.

Oestrus synchronisation was done in 20 repeat breeders and samples were collected on different days of post-insemination to estimate cortisol.

Trans-rectal ultrasonography on 26^th day of post insemination revealed a pregnancy rate of 45%. When two groups were compared, serum, salivary and urinary cortisol level of non-pregnant animals were significantly (P<0.05) increased than that of pregnant animals on different days of post-insemination. Within non-pregnant animals, serum, salivary and urinary cortisol levels showed a significant (P<0.05) variation between different days of post insemination, but this variation was not observed in pregnant animals. Spearman rho correlation revealed positive association (P<0.05) of systemic cortisol with pregnancy rate. In non-pregnant animals, salivary and urinary cortisol levels were observed to be positively correlated (P<0.05) with serum cortisol. The results indicate that systemic cortisol has influence on pregnancy rate in repeat breeding cows, this may be due to its effect on embryo implantation and hormonal balance, which requires further validation. Association of salivary and urinary cortisol with serum cortisol indicates their use as non-invasive samples to monitor the hypothalamic-pituitary-adrenal axis activity in repeat breeders.