Submitted to: Applied Animal Behaviour Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2003
Publication Date: 8/27/2003
Citation: DAMM, B.I., PEDERSEN, L.J., MARCHANT FORDE, J.N., GILBERT, C.L. DOES FEED-BACK FROM A NEST AFFECT PERIPARTURIENT BEHAVIOR, HEART RATE AND CIRCULATORY CORTISOL AND OXYTOCIN IN GILTS?. APPLIED ANIMAL BEHAVIOR SCIENCE. 2003. Interpretive Summary: Around the time of giving birth, the domestic pig carries out a unique set of behaviors. Under natural conditions, she isolates herself from the herd and spends a great deal of time and effort selecting a nest site and constructing a nest in which to give birth. Once satisfied with the nest, she burrows into the bedding and delivers her litter. It has been proposed that this sequence of nesting behaviors is initially internally-driven, by changing hormone levels, but that nest-building completion is reliant on environmental feedback - i.e. the presence of a suitable nest. The majority of sows in industrialized pig industries give birth in farrowing crates with little or no access to nest-building material and it has been shown that many sows under these conditions continue to perform nest-building-type behaviors, even during the time that they are giving birth. It has also been proposed that the lack of a completed nest is stressful, disrupting hormonal balances and potentially affecting piglet viability and survival. Our study aimed to investigate whether manual disruption of nest-building did affect the sow's stress levels and her subsequent behavior towards her piglets. This paper deals with the first aspect. We found that disrupting the nest did not affect either the quantity or the timing of nest-building behavior and did not affect the levels of the reproductive hormones oxytocin or estradiol. However, nest disruption did result in significant increases in heart rate and the levels of the stress hormone cortisol as time progressed from the start of nest-building towards the birth of the first piglet, even though activity, which elevates heart rate and cortisol levels, was decreasing. These results indicate that nest disruption was stressful. This means that producers should be aware that sows are highly motivated to build a nest as farrowing approaches and that the inability to do so, in most farrowing systems currently in use, probably stresses the sow at a time that might impact the survival of the litter. They should therefore consider any modifications to their farrowing systems that might alleviate this stress, such as providing the sow with access to some nesting materials.
Technical Abstract: To determine the effects of feed-back from a farrowing nest on periparturient behaviour, heart rate and hormones, 20 primiparous sows housed in Schmid pens were permitted to build a nest of peat, straw and branches. Ten primiparous sows then had their nest removed (NR) 10 h after the onset of nest-building and again every 4 h until parturition, whereas 10 sows were given sham removals (C). Based on video recordings, sow periparturient postures and nest-building behaviour from 7 h before birth of the first piglet until 6 h after was observed. Maternal heart rate was measured using a transmitter belt and a watch receiver and the heart rate during the last 7 h prepartum analysed. Maternal blood samples were taken via a jugular catheter every 20 min over the last 7 h prepartum and immediately after the birth of three different piglets within the first two thirds of parturition. Plasma concentrations of cortisol, oxytocin and oestradiol-17 within the last 7 h prepartum were determined as were the plasma concentrations of oxytocin and oestradiol-17 during parturition. Treatment did not affect the quantity or timing of nest-building and postural behaviour prior to or during parturition. Treatment also did not have an overall effect on prepartum heart rate. However, as parturition approached, heart rate increased in NR but not C sows (P = 0.03), although nest-building behaviour and activity decreased during this period in both groups (P = 0.05). Similarly, during the last 4 h prepartum plasma cortisol was higher for NR than C sows (P = 0.04). Plasma oxytocin and oestradiol-17 , however, were unaffected by treatment both prepartum and during parturition. The prepartum increases in plasma cortisol and heart rate in NR sows in the absence of greater activity suggest that nest removal was stressful. The observed treatment effects could have resulted from sows perceiving environmental novelty following nest disruption or a specific lack of feed-back from the nest. The results emphasise the importance of farrowing environment and the opportunity to construct a nest on sow welfare.