Behavioral Genetics in Pigs and Relations to Welfare - Genetics and the Behavior of Domestic Animals - page 403

In intensive, large-scale indoor production systems, a varying environ-
ment is probably not the main welfare problem. On the contrary, the unifor-
mity and lack of events may be a large challenge for growing pigs. Thus we
have to stress the question “Appropriate environment for whom?” Are there
any lines of pigs with the genetic ability to “thrive” in the ordinary indoor
conditions where pigs are usually kept during the growing finishing period?

The pig is an explorative animal, but there is not much to explore in pens for
growing pigs. Breed differences in explorative behavior have been found; in
a comparison between young Large White, Landrace and Duroc pigs, the
Durocs were more exploratory ( Breuer et al., 2003 ). Meishan sows perform
more explorative behavior than Large White sows ( Canario et al., 2009 ). In
the Code of good practice for farm animal breeding and reproduction organi-
zations ( EFAB, 2013 ) the industry has agreed that breeding organizations
must maintain “the intrinsic characteristics of domesticated species”. The
members of the Federation of Veterinarians of Europe are concerned about
breeding resulting in “animals with unnatural behavioral characteristics”

( FVE, 1999 ). The meaning of natural and unnatural for domestic animals
will be discussed later, but uncurious pigs could be regarded as unnatural.
“Freedom from Discomfort” also implies providing “a comfortable resting
area”. No matter how well designed the pen or the floor is, there will be little
rest if the pigs are continuously disturbing each other. Entire males perform
more social behavior than castrates and too much social behavior seems to
decrease animal welfare even when it is not painful ( Rydhmer et al., 2010 ).
Nosing, pushing, sniffing, and nibbling are social behaviors normally per-
formed by pigs. Bench and Gonyou (2007) found that breed and also sire
within breed had a significant effect on belly-nosing and sucking behaviors in
young weaned pigs. In a breed comparison by Breuer et al. (2003) , Duroc
pigs performed less belly-nosing than Landrace and Large White, suggesting
a genetic background to these behaviors. If rearing of entire males for slaugh-
ter would become the dominating production system, selection for an optimal
frequency of both aggressive and non-aggressive social behaviors could be
relevant.

...

FREEDOM FROM PAIN, INJURY OR DISEASE
Tail Biting
Tail biting is difficult to prevent because its occurrence has a multi-factorial
origin. The most extreme preventive treatment is to cut off the tails as a
means of improving pig welfare. According to the European Food Safety
Authority ( EFSA, 2007 ), over 90% of the pigs within the European Union
are tail docked, even though routine tail docking is prohibited (EU Directive
91/630 EEC). In Sweden, where no tail docking is performed, tail biting or
other tail damage is observed in 7% of the pigs at

the slaughter plant