Piglet mortality: causes and prevention - The Gestating and Lactating Sow - page 253

important breeding goal discussed by numerous authors (Damgaard et al. , 2003; Huby
et al. , 2003; Knol et al. , 2002a,b; Rydhmer, 2000). Selecting for improved placental
efficiency is another potential strategy to improve piglet outcomes (Van Rens et al. , 2005).
Furthermore, breeding for improved maternal behaviour (Baxter et al. , 2011a; Gade et
al. , 2007; Grandison, 2005) and defining new traits that characterise a more robust piglet
both have potential to reduce mortality.

11.3.2 Environmental design

Previous research to reduce piglet mortality was centred almost entirely around
alterations to the farrowing environment. Increased control over the macro- and micro-
climate of the birth site and nest area (Morrison et al. , 1983; Schmid, 1994) and, of
course, the introduction of the farrowing crate (Robertson et al. , 1966) are some examples
of tools put in place to improve piglet survival. Whilst the farrowing crate has given
significant benefits for piglet survival (Edwards and Fraser, 1997), it imposes physical
restrictions that impact on sow welfare, preventing the fulfilment of important species-
specific behaviours such as nest-building. Lawrence et al. (1994) found elevated cortisol
levels in crated sows and hypothesised that this was a consequence of the inability to
perform natural behaviours and a likely factor contributing to increased savaging in
restrictive environments (Jarvis et al. , 1998, 2004; Lawrence et al. , 1994; McLean et al. ,
1998). Improving maternal behaviour and farrowing progression by reducing stress in
the periparturient sow can indirectly assist the piglet. Farrowing duration, and risk of
hypoxia, may be reduced by ensuring appropriate sow condition, minimising heat stress,
and providing enrichment to allow nest-building behaviour and reduce frustration
(Damm et al. , 2003, 2005; Jarvis et al. , 2001, 2002; hodberg et al. , 1999). In choice
experiments (Herskin et al. , 1998), provision of bedding and substrate improved maternal
behaviour by reducing the number of posture changes, thereby diminishing crushing
risk. Providing substrate will not only improve maternal behaviour but will also provide
a micro-climate for newborn piglets. The importance of designing facilities to minimise
hypothermia at birth was illustrated in the early experiments of Morrison et al. (1983),
using supplementary radiant heating at the birth site and adjacent to the udder where
piglets spend the early hours of postnatal life. Such provision is easy in a farrowing crate
system which fixes the sow's location, but is more challenging in a loose farrowing pen
where the birth site cannot be reliably predicted. In loose pens, a significant reduction in
mortality was demonstrated with the use of floor heating in the nest area (Malmkvist et
al., 2006). Where loose farrowing pens are used, the incorporation of piglet protection
features, such as sloped walls to assist controlled lying by the sow and facilitate piglet
escape, are also critical features for success. The design of new farrowing systems, and
adjustments to existing systems, should consider options that build on understanding
pig behaviour in order to optimise both sow and piglet welfare (see review of Baxter et
al. , 2011b).