Generally, pigs
are habitual animals and probably the majority of sows kept in gestational
stalls are relatively content to be there. However, a significant proportion
found it restrictive and to vent their frustration adopted certain vices, like
stall biting etc.
We must remember
how stalls came about. I remember Prof Richard Penny of London University
relating the tale. When dry sows were kept in yards and floor fed, there was
always a problem of feeding. There would be some fat sows, some medium sized and
some thin sows, which were bullied off the feed and did not get enough. Somebody
came up with the bright idea of individual feeders and this protected the
smaller, thinner sow and enabled her to get the right amount of food. Often,
even after feeding, sows would stay and lie in the stalls, presumably, for
protection. As a result, it was concluded; let's leave them in the stalls and
the development of the gestation crate system arrived. There are distinct
advantages, of reduced housing area, waste management with slatted floor/slurry
systems, better observation of the animals and reduced labour input. The
drawbacks were on the perceived welfare issues, stemming from the so-called
'five freedoms', of discomfort, increased leg injuries and restricted movement
and behaviour, which was demonstrated by the abnormal vices.
In the UK, when
we changed back to yards, or in some cases, outdoor reared sows, we had to
relearn the management skills of before, such as individual feeding control,
whether through individual feeders or automated electronic feeders, to protect
the sow from bullying and vulva and anus biting, but this took some time. In
addition, we have the additional problems of manure/straw management, sow
handling and poorer observation.
Overall, I don't
think we want to go back to the gestation stall system, but for those countries
that will have to change by 2013, forward planning and research to see what is
the best way forward is required to make it a relatively smooth transition,
without inducing increased welfare problems.