Oxytocin delivered intranasally to gilts immediately after the birth of the first piglet decreased colostrum intake and growth of piglets

Oxytocin has a role in maternal care, maternal aggression and anxiety (Sabihi et al. 2014). When the effect of oxytocin was blocked in rodents, maternal care was impaired, conversely, increasing oxytocin improved maternal care and evoked maternal behaviour in virgin animals (Slattery and Neumann 2008). There are two pools of oxytocin; a central pool (within the brain) and a peripheral pool (outside of the brain). Delivery of oxytocin intranasally, via nasal spray has been shown to reach the brain, and actions of oxytocin through the brain are more likely to be directly involved with the control of behaviour (Neumann 2008). We hypothesised that a single intranasal dose of oxytocin delivered to gilts immediately after the birth of the first piglet would potentiate mother/offspring bonding, increase colostrum intake by piglets and increase the growth of piglets.

Gilts were randomly allocated to treatments and housed in conventional farrowing pens at Roseworthy piggery, Roseworthy, SA at ~110 days of gestation. The experiment was run over three replications in time. Treatments consisted of: a single 25 µg dose of oxytocin diluted in 1 mL saline (Auspep pty ltd, Melbourne Australia. equivalent to 12 IU) (n = 18) or a 1 mL dose of saline (n = 13) up one nostril immediately after the birth of the first piglet. Gilts were continually monitored by technicians throughout parturition in order to collect the following measures: farrowing duration, inter-piglet birth interval, total piglets born, piglets born alive, piglets born dead, 3-day piglet weight, 18-day piglet weight and the number of piglets saved from the sow by the researchers. Colostrum intake in the first 24 h was calculated using the method described by DeVillers et al. (2007). Data were analysed using a general linear model (sow measures) or a mixed model (piglet measures) in SPSS v24.0 (IBM, Armonk, NY, USA).

The number of piglets that had to be saved by the researchers during parturition because of risks of savaging or crushing was greater for gilts that received oxytocin than for gilts that received saline (Fig. 1; P < 0.05). Colostrum intake, 3-day piglet weight and 18-day piglet weight were significantly lower in piglets from gilts that received oxytocin than those that received saline (P < 0.05) There was a trend (P = 0.065) towards a reduction in farrowing duration, saline 240.85 min ± 29.75 and oxytocin 168.16 min ± 22.04 (mean ± s.e.m.), birth intervals and piglets born alive or dead did not differ between treatment (P > 0.05).

Fig. 1.  The effect of 25 µg of oxytocin delivered intranasally to gilts, on colostrum intake, piglet weight at d 3 and 18 and the number of piglets saved. *, P < 0.05.

Our data do not support our hypothesis, as the administration of intranasal oxytocin to gilts during farrowing had a negative impact on their piglets’ colostrum intake and growth. Gilts that were administered oxytocin spent significantly greater time ventral lying than lateral lying and this likely reduced the opportunity for piglets to suck. Future research is required to further explore the effect of intranasal oxytocin on gilt maternal behaviour, to determine if the dose of oxytocin was appropriate, and the most appropriate time to administer oxytocin intranasally.