Long-stemmed straw as an additional nesting material in modified Schmid pens in a commercial breeding unit: effects on sow behaviour, and on piglet mortality and growth

The aim of this study was to determine whether provision of nest materials in a form and amount that could be handled in a commercial Danish pig farm with modified Schmid pens would affect the environment for sows and piglets to an extent that could be detected in sow behaviour and parameters relevant both for production and piglet welfare, i.e. piglet mortality and growth. Three-hundred twenty-six farrowings were included in the study and the sows in the treatment group were provided with 2.5 kg long-stemmed barley straw from 2 days prior to expected farrowing until 4 days after farrowing in addition to the 4 kg chopped straw that was given both at treatment (n = 163) and control farrowings (n = 163). The median mortality rates (and interquartile ranges) due to still-birth were 6.7 (0-17.6) and 6.3 (0-13.3)% for the treatment and control group, respectively. The median mortality rates within the first 3 weeks after birth for live-born piglets that remained with their biological mother, i.e. piglets that were not cross fostered, were 18.2 (6.3-30.8)% and 20.0 (7.7-30.8)% for the treatment and control group, respectively. On average, the live-born piglets that had remained by their biological mother died 0.76 +/- 0.05 days after birth in the treatment group and 0.74 +/- 0.06 days after birth in the control group. The primary mortality causes were still-birth and piglet crushing, but 72% of all the live-born piglet which died had also not received colostrum. The mortality rates, the distribution on specific mortality causes and the time of death did not differ between treatments. The results indicate that 2.5 kg long-stemmed straw in addition to the chopped straw provided to both groups was insufficient to achieve the positive effect on maternal behaviour suggested possible in previous more fundamental studies of provision of nest materials to sows. This conclusion was supported by behavioural observation on a randomly selected subset sample (27 treatment farrowings and 20 control farrowings). The observations revealed no significant differences between treatment and control group in frequency of nest building or lying in lateral recumbency without changing posture from 4 h prepartum until 6 h postpartum. There was also no difference in the inter birth intervals or percentage of the litter that was suckling during the first 8 h after birth of the first piglet. The results emphasise the need for further studies of the amounts and types of nest materials that should be given in order to fulfil the intention of the EU requirement for nesting materials to periparturient sows, and to obtain the effects on behaviour and production that have been suggested possible by previous more fundamental studies on nesting materials to loose housed sows. (c) 2004 Elsevier B.V. All rights reserved.