Genetics and Behavior During Handling, Restraint, and Herding - Genetics and the Behavior of Domestic Animals - page 132

multiple potential sources of phenotypic variation, and each of these sources
reflects a different underlying cause.
One source of variation is found in Bergmann's rule. This principle that
states that within a broadly distributed genus, species of larger size are found
in colder environments, and species of smaller size are found in warmer
regions. These differences are described by Goodwin (2002) , and Moen
(1973) identified a geographic cline (gradual change) that affects morphol-
ogy and behavior. Individuals from the northern extent of the range tend to
be stockier—with adaptations for energy conservation in cold climate—and
to have less reactive temperament. Individuals from the southern extent tend
to be more gracile (slender) in build—with adaptations to heat dissipation in
hot climate and a tendency to be more reactive. A clear example of this prin-
ciple can be seen in differences between Bos Tauras (English and
Continental breeds) and Bos Indicus (Brahman) cattle. The phenotypic varia-
tion is obvious in body shape and size, coat colors, and temperament.
Considerably more phenotypic variation exists in domesticated species like
dogs than in non-domesticated species. Domesticated species differ from their
wild ancestors in a number of physical characteristics and traits, generally
referred to as the domesticated phenotype. Domestication produces simulta-
neous changes in a number of both physiological and behavioral traits
(Kukova, et al., Chapter 10). It has been shown that selection for one trait asso-
ciated with the domestic phenotype can lead to simultaneous changes in others.

Body Type and Temperament in Domestic Animals
Body shape in animals is related to temperament. Krushinski (1961) reported
that slender, narrow-bodied dogs had increased excitability compared to
“athletic wide-bodied” dogs. The narrow-bodied dogs were more fearful.
Martins et al. (2009) used 11 body measurements in Braford cows and clas-
sified temperament using both a restraint test and an exit speed test. Animals
of big body size performed better in the temperament tests compared to the
groups with medium and small body size. The first author has observed that
selecting pigs and cattle for lean meat and thin back fat has resulted in ani-
mals that are more reactive to sudden novelty. This idea is supported by Holl
et al. (2010) who found that leaner pigs were more agitated on a weigh scale.
When animals are selected for leanness and bulging muscles they tend to be
less reactive than lean, smooth-bodied slender animals. However, both types
of lean animals are probably more reactive than animals with more body fat.
Holmes et al. (1972) found that double-muscled Angus cattle had more
excitable temperament scores. The first author observed that Charolais cattle
bred in Quebec, Canada, with heavy bones and muscular bodies are very
calm at a noisy livestock auction compared to slender lean Charolais cattle
bred in the U.S. When we looked at the different body shapes and sizes of
different breeds of pigs, cattle, and horses,

the physique temperament