Agriculture Reference
In-Depth Information
recent study, Andersen
et al.
(2006) saw no clear influence of positive handling at the end
of pregnancy on the duration of farrowing. However, within the group of control sows
(sows without additional positive contacts), they observed that females having a higher
confidence score at the end of pregnancy tended to have a shorter farrowing duration.
Within the group of positively-handled sows, a similar difference was observed but it
was less marked as if the positive handling procedure had partly compensated for the
low confidence score observed before its application. Therefore, a positive perception
of humans (either spontaneous or after extensive positive handling) may facilitate the
farrowing process.
12.3.4
Parity effect on the sow's reactions to handling
Parity may affect the responses of sows to handling procedures, likely due to a learning
process. Yet, there is no general rule on the effect of parity since very few studies were
carried out. In some cases, sows react less to humans with advancing parities. For
instance, fear of humans seems to decrease with parity, gilts being less receptive (i.e.
expressing less attraction toward humans) to friendly contacts than sows in their third
parity (English
et al.,
1999). Primiparous sows also react more quickly than multiparous
sows to handling of their piglets by a human (Held
et al.,
2006) or to the playback of
screams of piglets being handled by a human (Hutson
et al.,
1992). They may learn
that there is no negative consequence of this handling situation, thereby becoming less
reactive with time. Evidence of such a learning process was also shown in 90 kg-pigs,
where training pigs to be transferred decreased their stress responses and increased the
speed of the transfer procedure (Lewis
et al.,
2008).
In other cases, a greater parity number was associated with higher withdrawal responses
in a human approach test, higher speed of transfer to the farrowing pen, and lower
number of baulks (Lensink
et al.,
2009a). The higher withdrawal responses clearly
indicated greater fearfulness of humans in older sows. The higher speed of transfer was
also likely related to greater fearfulness since fearful animals may move more quickly
in order to escape the stockperson who is behind them. This hypothesis is supported
by the positive correlation reported between the speed of transfer and the withdrawal
responses (Lensink
et al.
, 2009a). The negative correlation observed between the number
of baulks and the withdrawal reactions also supports that the lower number of baulks
observed in higher parity sows was a sign of greater fearfulness. The observation of an
increase in the withdrawal response to humans with advancing parities is in agreement
with findings from Hemsworth
et al.
(1999) but opposite to those of Grandinson
et al.
(2003) and Vangen
et al.
(2005). The positive or negative influence of parity on fearfulness
at a given age, likely depends on the quality of the interactions until that age. It can be
hypothesized that if the balance between negative and positive interactions with humans
is clearly biased towards negative interactions, the animals become more and more fearful
of humans.
