The productivity and behaviour of sows and piglets housed in farrowing pens with temporary crating or farrowing crates : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science, Massey University

Pen-based alternatives to farrowing crates have been researched for decades, in an effort to improve the welfare of farrowing and lactating sows. However, high piglet mortality, and a lack of commercially-relevant studies, has been a barrier to the acceptance of these systems in the pork industry. The purpose of this thesis was to compare the performance and behaviour of sows and piglets in farrowing pens with temporary crating, and in farrowing crates, in a commercial setting. In the first study, sows were housed in either a farrowing crate from 5 days pre-farrowing until weaning at 28 days; or in a pen where sows were crated from 3 days pre-farrowing until the 4th day of lactation. The farrowing system (crate or pen) from which a sow was weaned had no effect on subsequent reproductive performance. However, pre-weaning piglet mortality was significantly higher in pens (10.2%) than in crates (6.1%). Sow and piglet behaviour was studied during the first 6 days post-farrowing in the second study. Sows in crates were confined throughout this observation period, whereas sows in pens were crated for days 1 – 3 post-farrowing and loose in the pen during days 4 – 6 post-farrowing. There was no difference between systems for the amount of time sows spent lying or standing during days 1 – 6, though sows in pens were more active once they were loose. Penned sows touched and investigated their piglets more once they were loose, compared to when they had been crated. There were few differences in piglet behaviour between farrowing systems. The influence of the birth and rearing location (crate or pen) on gilt behaviour was examined in the third study. Gilts were identified as having been born and reared in a farrowing crate or in a pen. Gilts and their piglets were observed during the first three days after giving birth in the system they were born and reared in, or in the system they were not born and reared in. Gilts born and reared in pens with temporary crating touched and vocalised towards their piglets more than gilts born and reared in farrowing crates, irrespective of whether they farrowed in a crate or a pen. This finding has implications for the transmission of maternal behaviour. The associations between sow behaviour, gilt behaviour and piglet behaviour were compared in farrowing crates and pens with temporary crating using the data of the second and third study. Some associations between sow and piglet behaviour changed when the sow was no longer confined in a crate. This finding could be the link that explains differences in the later behaviour of gilts that were reared in different systems. Future studies should focus on the transition period between a sow being crated and then let loose in a pen, to improve sow and piglet welfare in these systems