Agriculture Reference
In-Depth Information
prolongs the farrowing duration (the consequences of which have already been discussed)
and increases the risk of crushing.
Crushing is generally reported as being the ultimate cause of the majority of neonatal
deaths and, given its importance, is a well-researched area of the hypothermia-starvation-
crushing complex. Sow behaviours influencing the risk of crushing include lack of
piglet-directed pre-lying behaviour, designed to remove piglets from the lying location,
frequency and nature of posture changes and failure to rise in response to a trapped piglet
(Andersen
et al.
, 2005; Marchant
et al.
, 2001; hodberg
et al.
, 2002). The latter aspect
is affected by the sow's body condition, which may be linked with parity, as well as her
inherent responsiveness and her farrowing environment. Older sows may experience
increased leg weakness, impeding posture changes (Damm
et al.
, 2005; Pedersen
et al.
,
2006), whilst the enforced restraint of a farrowing crate can limit the effectiveness of a
sow's response to a crushed piglet.
The sow's temperament also influences piglet mortality (Marchant
et al.
, 2001). here
are individual variations regarding maternal ability and sows who are deemed 'crushers'
behave differently than 'non-crushers' (Andersen
et al.
, 2005; Jarvis
et al.
, 2005). he
consistency of behavioural patterns within individuals, and the high variation within
populations, suggests a possibility of selecting for 'non-crushers' (Grandison
et al.
, 2003).
Neophobia and nervousness towards humans were also found to be associated with piglet
crushing (Lensink
et al.
, 2009), probably through increased reactivity to disturbance.
When litter size routinely exceeds the number of functional teats there is an increased
incidence of teat disputes amongst siblings causing increased disturbance at the udder,
which can lead to sow' restlessness and a larger number of sow-terminated nursings
(Chapter 13; Špinka and Illmann, 2015).
Crushing is not the only maternal behaviour that can directly cause piglet death - mis-
mothering in the form of maternal aggression or savaging can result in traumatic or fatal
injuries. Savaging is more prevalent in gilts (Chen
et al.
, 2007; Harris
et al.
, 2003; Vangen
et al.
, 2005), potentially because of a neophobic reaction to newborns. Higher incidences
of savaging are reported when sows are confined in crates and are unable to escape the
attention of the neonates (Lawrence
et al.
, 1994), whereas this behaviour is rarely seen
in alternative systems. Savaging sows are more restless and overly responsive towards
their piglets during parturition (Ahlstrom
et al.
, 2002). Thus, even if piglets escape direct
aggression, they risk being crushed and udder access is delayed. In addition, piglets are at
risk of infection and later death if they sustain non-fatal injuries as a result of over-lying
or savaging by the mother.
11.2.2
Piglet factors
This section will detail the consequences of piglets being born with physical and
behavioural detriments, with particular reference to their links with chilling, reduced
colostrum intake and crushing.
