Biology Reference
In-Depth Information
FIGURE 11.1 The pig is a generalist. Feral pigs are common, e.g., in Australia, and in Europe
wild boar pigs thrive in the city center. These pigs live in Berlin. Photograph: Florian Mo¨llers/
wildesBerlin
U.S.A. ( Wyckoff et al., 2009 ) and Dzieciolowski et al. (1992) report that
under the pressure of natural selection, characteristics of feral pigs return to
those of wild boars.
Two common tests used for genetic studies of individual temperament are
the open-field test and the novelty test. The open-field test was developed for
rodents. Animals are tested in an open field to induce a conflict between
aversion and voluntary exploration of a novel environment. Locomotion and
exploration are used as indicators of adaptation to change. A short period to
the first move in the open field and a high level of activity may reflect a low
level of anxiety ( R´ale et al., 2007 ), but the interpretation of pigs' reactions
has been questioned since pigs and rodents do not exhibit the same motiva-
tional processes. The response to novelty can be measured by introducing a
novel object in the home pen, or in a test arena after a period of acclimatiza-
tion to the novel environment. Usually, the first reaction to the novel object
is to freeze. The latency until the animal reacts, i.e. moves or gets in contact
with the object, is used as a measure of its boldness ( R ´ ale et al., 2007 ).
Even though pigs show the ability to modify their behavior to adapt to
the present environment, many behaviors are repeatable across situations and
some of them are inherited. Behavior traits do, however, differ from many
other traits in that they are changed by experience and learning. For instance,
there is a strong effect of age on the interest for a given object used in the
novelty test ( Docking et al., 2008 ). Early contact with humans influences
subsequent levels of fear ( Hemsworth and Barnett, 1992 ). Thus, individuals
in a group of young pigs may enter the growing
finishing facility with very
different experiences. They may also have different genotypes, for example,
regarding explorative and aggressive behavior.
Search WWH ::




Custom Search