Genetics and Animal Welfare - Genetics and the Behavior of Domestic Animals - page 452

Since these mice lack normal habituation, their welfare may be severely
compromised during standard laboratory procedures. To maintain an
acceptable level of welfare, these mice need to be housed in conditions where
exposure to sudden novelty is minimized. Severely compromised welfare can
occur in these high-fear mice if not slowly trained to tolerate novelty.
Selecting for excessive appetite motivation may cause stress, stereotypies, and
other abnormal behaviors, especially in feed-restricted breeding animals. If
stereotypies develop in large numbers of breeding animals housed and fed
under the best conditions, genetic selection may have gone too far in the wrong
direction. In some situations, a genetic line with low levels of repetitive stereo-
typies had higher-fear temperaments ( Hansen and Jeppensen, 2006; Svendsen
et al., 2007 ). More recent research has shown that relationships between
temperament and high and low stereotypies are not simple. Minks showing
low fear when fear was measured by willingness to explore a stick stuck in
their cage may become very frightened when fear is measured with a different
method. Minks with high levels of stereotypies had higher fecal cortisol
metabolites after they were immobilized ( Malmkwist et al., 2011 ). High
stereotyping minks had more kits, but the low stereotyping minks had fewer,
better-quality kits ( Meagher et al., 2012 ). Maybe the high stereotyping minks
were high “seekers” and more willing to approach novelty (see Chapter 1).
Malmkwist et al.(2011) conclude that minks with high stereotypies may be
more sensitive to stress. An animal demonstrating continuous stereotypies has
severe difficulty with basic functioning.
Siamese cats with mildly crossed eyes have good welfare, but animals
bred to have constant epileptic seizures may have poor welfare if not housed
in an environment free of seizure triggers. It is clear that animal welfare pro-
blems have occurred in some animals as a result of overzealous selection for
a single trait. Many dog breeds have structural problems that compromise
welfare ( Ackerman, 2011; Arman, 2007; Ott, 1996 ). Some examples are eye
problems in collies, back problems in dachshunds, breathing problems in
bulldogs, and hip problems in many breeds. Many of these traits can be
selected without compromising welfare if selection is done in moderation.
Animal breeders need to take a more holistic view when selecting breeding
stock, and think about optimizing the whole animal instead of selecting for
a few traits. This would help prevent the mistakes made by pig breeders
discussed earlier in this chapter. Pig breeders selected for production traits
and forgot to examine animals for structural soundness, and failed to see the
leg problems until half of the pigs became lame.
The science of genetic engineering now makes it possible to delete genes
or swap genes between species. A major difference between conventional
selective breeding and genetic engineering is that the process of selection is
greatly sped up ( Fox, 1989, 1992; Grandin, 1991; Rollin, 1995 ). The speed
of change is accelerated to a point where less time is available to take
corrective action if selection mistakes are made.