Genetics and Animal Welfare - Genetics and the Behavior of Domestic Animals - page 445

and Rogers (1961) discovered a preference for alcohol over water in an
inbred mouse line. Crabbe (1983) found two distinct genetic effects and two
separate behavioral effects of alcohol. The first effect of alcohol on mice is
on activity levels after a dose. The second is “hypothermic sensitivity” which
includes a long sleep time after a dose of alcohol.
In rodents and small mammals used for research, welfare problems can
appear unexpectedly. In a German laboratory, workers reported an outbreak
of self-mutilation in checkered cross rabbits bred for a high resistance to
infection ( Inglauer et al., 1994 ). The rabbits bit off their own toes. The
researchers achieved the goal of increased disease resistance, but the price
was rabbits that injured themselves. This experience is just one more exam-
ple of behavioral and physiological traits linked in ways that are difficult to
predict.
DEPIGMENTATION PATTERNS AND THE NERVOUS SYSTEM
For centuries, animal breeders have recognized that a lack of eye and body
pigmentation may signal neurological defects. Animals with extensive depig-
mented areas on the body are more likely to have developmental or nervous
system abnormalities ( Cowling et al., 1994; Searle, 1968; Webb and Cullen,
2010 ). The degree of depigmentation could possibly serve as an early warn-
ing for welfare-related nervous system abnormalities in animals highly
selected for production traits.
It is important, however, to differentiate between depigmentation and ani-
mals with white hair and fully pigmented skin. Arab horses and Brahman
cattle have light hair and dark skin. Depigmented areas of the body are char-
acterized by both white hair and pink skin. The Holstein cow is depigmented
in the white areas of the body. Light-colored cattle, such as the Charolais,
are not depigmented and have brown eyes and some hair pigment. Most
beef breeds do not have large areas of depigmentation. In addition, some
crossbred white pigs with Duroc genetics have white hairs with a very faint
reddish tint. The Yorkshire and Landrace pig breeds have dark-colored eyes
and white hair and skin.
Coat color and patterns are controlled by a common genetic mechanism
in many different mammals ( Murray, 1988 ). For example, many domestic
animals have a white blaze on the forehead and a white tail tip. Dogs, cats,
and cattle are all found to have this pattern. Schaible (1969) and Schaible
and Brumbaugh (1976) explain that migration of pigment-producing cells
occurs during embryonic growth, and common patterns between species
frequently occur. For example: mice can be selected for a white belt on a
mostly black body. This pattern is very similar in appearance to that of
Hampshire pigs and Belted Galloway cattle. The common white areas in all
three species are characterized by a lack of pigment, both in the hair and in
the skin beneath the hair. In domestic horses, depigmented facial and leg