Cortisol Profiles in Sows Submitted to an Intermittent Suckling Regime Compared with that of Abruptly Weaned Sows

Abstract

The aim of this study was to monitor changes in cortisol levels in sows around the time of separation from their piglets, in two different intermittent suckling regimes, compared with that in conventionally weaned sows. Sows were either weaned at 21 days of lactation (CONT) or subjected to an intermittent suckling regime (IS) from 14 days of lactation onwards. Sows in the IS regimes were separated from their piglets for 12 h every day, either from 08:00 to 20:00 hours (IS12) or from 08:00 to 14:00 hours and 20:00 to 02:00 hours (IS6). Separation caused a transient increase in cortisol levels on the first (CONT and IS12) and second (IS12) day of separation, compared with a gradual decline from early morning when the sows were still continuously suckling. In IS6 sows, in contrast, the transient rise in cortisol levels after separation at 08:00 hours was observed on the first 3 days and also on day 7 of the IS regime. Cortisol parameters were correlated with peri-ovulatory characteristics like onset of oestrus, onset of the LH surge and time of ovulation. Onset of the LH surge was delayed in IS6 sows. In conclusion, increase in cortisol levels as a consequence of separation of sows and piglets, is an acute, incidental phenomenon in IS12 and CONT sows, but shows a repeated acute elevation in IS6 sows, possibly placing IS6 sows at a higher risk of influencing peri-ovulatory processes and developing cystic follicles.