Does feed-back from a nest affect periparturient behaviour, heart rate and circulatory cortisol and oxytocin in gilts?

Abstract

To determine the effects of feed-back from a farrowing nest on periparturient behaviour, heart rate and hormones, 20 gilts housed in Schmid pens were permitted to build a nest of peat, straw and branches. Ten gilts then had their nest removed (NR) 10h after the onset of nest-building and again every 4h until parturition, whereas 10 gilts were given sham removals (C). Based on video recordings, gilt periparturient postures and nest-building behaviour were observed from 7h before until 6h after the birth of the first piglet. Maternal heart rate was measured using a transmitter belt and a watch receiver and the heart rate during the last 7h prepartum analysed. Maternal blood samples were taken via a jugular catheter every 20min over the last 7h prepartum and later analysed for plasma concentrations of cortisol and oxytocin.Treatment did not affect the quantity or timing of nest-building and postural behaviour prior to or during parturition. However, treatment significantly affected changes over time in heart rate and plasma cortisol as parturition approached. Heart rate (P=0.008) and plasma cortisol (P=0.002) increased for NR gilts, but remained constant for C gilts, although nest-building activity decreased during this period in both groups (P=0.006). Plasma oxytocin was unaffected by treatment. The prepartum increases in plasma cortisol and heart rate in NR gilts in the absence of greater activity suggest that nest removal was stressful. The observed treatment effects could have resulted from gilts perceiving environmental novelty following nest disruption, a specific lack of feed-back from the nest or disturbance from nest removal activity per se. The results emphasise the importance of the farrowing environment and the opportunity to construct a nest on sow welfare.