Abstract

This study investigated the effect of continuous elevated cortisol concentrations during standing oestrus on time of ovulation and patterns Of progesterone. oestradiol and luteinising, hormone (LH) in sows. The elevation of cortisol concentrations was achieved through repeated intravenous injections of synthetic adrenocorticotropic hormone (ACTH) every 2 It for approximately 48 h, from the onset of the second standing oestrus alter weaning. Treatment was terminated when ovulation was detected (monitored by transrectal ultrasonography every 4h) or when (lie sow had received a maximum of 24 injections. The close of ACTH (2.5 mu g/kg) was chosen to mimic the cortisol concentrations seen during mixing of unfamiliar SOWS. The sows (n = 14) Were surgically fitted with jugular vein catheters and randomly divided into a control (C group) where only NaCl solution were injected) or an ACTH group. Blood samples were collected every 2 h. In parallel with the blood sampling, saliva samples for cortisol analyses were taken from eight sows before onset of treatment and from four of the sows during treatment. There was no difference in time from onset of standing, oestrus to ovulation between the two groups. The interval between the peaks of oestradiol and LH to ovulation was prolonged in the ACTH group compared to the C group (p < 0.05). with a tendency towards all earlier decline of oestradiol in the ACTH group. Cortisol and progesterone Concentrations were significantly elevated during treatment in the ACTH group (p < 0.001). with cortisol peak concentrations occurring between 40 and 80 min after each ACTH injection. Cortisol concentrations in saliva and Plasma were highly correlated (p < 0.001). In conclusion, elevated cortisol concentrations from the onset of standing oestrus increase progesterone concentrations and prolong the interval between oestradiol and LH peaks to ovulation, the latter possible due to an early decline in oestradiol concentrations and a change of the LH peak outline. the effect these hormonal changes have on reproductive performance need to be further investigated. (C) 2008 Elsevier B.V. All rights reserved.

Keywords

Pig endocrinology; Cortisol; Oestradiol; LH; ACTH; Stress

Published in

Animal Reproduction Science
2009, volume: 110, number: 1-2, pages: 172-185

Authors' information