Housing, management and environment during farrowing and early lactation - The Gestating and Lactating Sow - page 223

increased farrowing time was either the direct result of less optimal conditions for nest-
building, or the indirect result of subsequent stress. Because pens allow the sow to better
express nest-building behaviour, at least in part, they are beneficial to the health and
welfare of both the sow and the piglets (Algers, 1994).

10.5.2 Effects of housing on hormonal variables associated with

farrowing

There is evidence that sows housed in crates show greater salivary cortisol concentrations
than sows in pens between 2 and 5 days post-farrowing (Oliviero et al. , 2008a). In the
penned group, during that period, cortisol concentrations returned to their pre-farrowing
levels instead of remaining higher as in crated group (Figure 10.2). This greater level of
salivary cortisol in crated sows could be linked to the prolonged duration of farrowing.
As previously mentioned, the lack of an environment in which the sow can fully express
nest-building behaviour (Jarvis et al. , 2002) contributed to raise the stress level beyond
a threshold above which other physiological mechanisms may have been altered. Lower
concentrations of oxytocin found in crated sows may explain such an alteration (Oliviero
et al. , 2008a) because insufficient concentrations of oxytocin at parturition are thought to
be an important cause of prolonged farrowing (Castrén et al. , 1993).

The average post-expulsion oxytocin pulse concentration (measured within 6 min after
expulsion of the piglet) for sows housed in crate was shown to tend to be lower than
that for sows housed in pens (Oliviero et al. , 2008a). The duration of farrowing was
strongly associated with these oxytocin concentrations. In addition, without taking into
consideration the different housing, farrowings longer than 5 h were strongly associated
with lower oxytocin concentrations.

Pen
Crate

40

30

20

10

0

-5 -4 -3 -2 -1 0 1 2 3 4 5

Days to farrowing (0)

Figure 10.2. Average salivary cortisol concentrations for sows housed in pens and in crates. Results are means
± standard deviation (Oliviero et al ., 2008a).