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lean growth and low back fat is associated with tail biting in Landrace pigs.
This agrees with the first author's observations of thousands of market pigs
at many slaughter plants. A much higher percentage of bitten tails is seen in
certain genetic lines of pigs. Pigs from these lines are more excitable and
chew harder on a person's boots compared to other genetic lines. Taylor
et al. (2010) has an interesting hypothesis and suggests three types of tail
biting, each with different motivations. The differences are referred to as;
“sudden,” “forceful,” and “obsessive” ( Taylor et al., 2010 ). The first author
speculates that intense, persistent boot chewing by these pigs may be the
“obsessive” motivation. Other forms of tail biting may be misdirected forag-
ing. Biting tails and fighting may have two totally different motivations.
Tail-biting pigs spend more time manipulating enrichment devices
( Zonderland et al., 2011 ), and victims of tail biting are more aggressive than
pigs that bite tails. Misdirected foraging is very different than aggression
( Zonderland et al., 2011 ). On a novel object test, tail biters had lower anxiety
compared to victims ( Zupan et al., 2012 ). Sinisalo et al. (2012) report breed
differences in tail biting and found that when Yorkshire and Landrace pigs
are mixed, the Yorkshires are more likely to be victims of tail biting. When
the first author visited Japan, she observed confinement-reared pigs that did
not have to have their tails docked to prevent tail biting ( Figure 12.1 ).
Whether tail biting is motivated by aggression or misdirected foraging, Van
der Weerd et al. (2008) found that the use of straw and chewable enrichment
devices may help to prevent severe tail biting. In this study, three enrichment
procedures were used; straw, a rootable feed dispenser, and a feed dispenser
providing flavorful water when chewable rods were manipulated. Results
show that a full bed of straw was the most successful way of occupying the
FIGURE 12.1 These Japanese pigs seldom bite tails even though they live in an environment
that is barren. Genetic factors have an influence on the occurrence of tail biting.
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