The primary aim of this thesis was to facilitate the commercial uptake of free
farrowing systems by providing management recommendations based on scientific evidence. The included management strategies were designed to be implemented easily and to have tangible benefits for piglet survival and performance.
All known establishments in the UK which currently use both conventional farrowing crates and less confined farrowing systems - both in industry and research - do so within the same herd and interchange sows between the confined and unconfined farrowing systems. Chapter three is the first published research to present the role of the previous farrowing system on piglet mortality, and confirmed the hypothesis that piglet mortality can be reduced by returning sows to the same farrowing system amongst both conventional farrowing crates and free farrowing pens (but not temporary crates). Piglet mortality was highest amongst sows which were interchanged between conventional and temporary crates, whilst sows which farrowed in free farrowing pens had a larger subsequent litter size and lower pre- processing crushing mortality in their second parity. Parity effects were also observed, with only pre-processing or post-processing mortality affected by the current farrowing system in the first or second parity, respectively. Individual differences in mortality were consistent throughout the first but not second parity. Additionally, to further research the role of previous farrowing experience, Chapter four compared the farrowing behaviour of second parity sows whilst housed in free farrowing pens, who had previously farrowed in either a free farrowing pen or
temporary confinement crate. Differences were observed between sows with different prior farrowing experience, confirming the hypothesis that sows which previously farrowed in a free farrowing pen would exhibit better farrowing behaviour, and expanding upon findings from previous studies (Jarvis et al., 2001; Thodberg et al., 2002a, 2002b). During parturition, sows with prior free farrowing pen experience exhibited increased lateral lying and decreased ventral lying, sitting and dangerous posture changes during parturition. Postpartum, the average duration of nursing bouts was increased, whilst the percentage of nursing bouts that were successful increased and those that were sow-terminated decreased amongst these sows. The study also found associations between nesting, partum and postpartum behaviours similar to previous studies (Thodberg et al., 2002a, 2002b). Finally, sow behaviour
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also showed seasonal variation, with the frequency of nesting, intensity of peak nesting and successful nursing bout duration all increased in the autumn/winter than the spring/summer.
Temporary confinement crates are often considered a more reasonable compromise to free farrowing for commercial use, as sows are confined during the first few days postpartum when piglet mortality is greatest. However, the abrupt environmental change that occurs when temporary confinement crates are opened may cause piglet mortality to increase as sows are required to adapt their behaviours mid-lactation. Chapter five is the first published research to confirm that piglet mortality risk
increases after the opening of temporary confinement crates. The study also trialled different crate opening strategies, which had different short-term effects on sow behaviour, and identified a strategy which successfully reduced piglet mortality during the post-opening period.
Commercial farms regularly perform cross-fostering to equalise piglet number and size across litters. Moreover, late cross-fostering, performed after 24 hours
postpartum, is likely to become more prevalent with increasing live born litter sizes and the subsequent reliance on foster and nurse sows. Because sows are highly maternal and protective of their offspring, late cross-fostering was hypothesised to be more disruptive amongst penned sows, which have greater freedom to interact with unknown piglets. Chapter six will be the first published study to compare the effects of late cross-fostering on sow behaviour and piglet weight gain amongst both penned and crated animals, which confirmed the hypothesis that sow behaviour would be more disrupted, and piglet weight gain more reduced, after late cross-fostering in free farrowing pens. Specifically, it was found that penned foster sows exhibited
increased ventral lying, decreased lateral lying and decreased nursing bout
frequency on the day following cross-fostering. This was associated with the reduced weight gain of both resident and foster piglets immediately after cross-fostering and a continued reduction of weight gain for foster piglets throughout lactation and of
resident piglets.
The thesis focussed on management alterations, rather than management additions. Stockperson time is already limited, therefore alterations to existing routines are more likely to remain implemented in the long-term instead of recommending additional practices, such as increased supervision of farrowings or drying of new-born piglets (Kirkden et al., 2013; Rosvold et al., 2017), which may be both unrealistic to perform
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consistently and unsustainable in a commercial setting. The thesis also aimed to highlight the imperative need to work with, and not against, the natural behaviour of sows in order to manage free farrowing systems successfully. Farrowing crates facilitate various management practices designed to promote piglet survival – such as split suckling, cross-fostering and supplementary feeding of piglets (Baxter and Edwards, 2018) – by protecting the piglets, giving stockpeople safe and easy access to assist piglets and limiting the possible behavioural responses of the sow.
Therefore, stockperson routines whose effects may not be very noticeable on the behaviour of confined sows can have a significant impact on the behaviour of sows in unconfined farrowing systems. Ensuring systematic practices which support the correct performance and development of sow maternal behaviours throughout their reproductive life should reap returns in improved sow productivity and piglet survival. This style of management is arguably of vital importance for the commercial success of free farrowing systems, where sow farrowing and maternal behaviour has a more tangible effect on piglet survival and performance than when housed in the
behaviourally restrictive conventional farrowing crate.