Reproductive and Maternal Behavior of Livestock - Genetics and the Behavior of Domestic Animals - page 158

breeding patterns, male reproductive capability is maintained throughout the
year, even though libido, spermatogenesis, and male fertility may be lowered
during the non-breeding period. Although artificial selection has changed
many characteristics of domestic animals, it has had relatively little effect in
altering the breeding patterns of seasonal breeders despite economic pres-
sures to do so, for example in horses ( Chemineau et al., 2008 ).
Environmental change is also relevant to this discussion on genetic
aspects of reproductive and maternal behavior, with the greatest effects being
likely in those species which rely upon seasonal changes for breeding, hiber-
nation, or migration ( McPherson and Chenoweth, 2012 ). For example, the
time of mating in many mammalian species has evolved within their envi-
ronmental context in which seasonal differences occur in nutritional
resources. This is most evident in seasonal breeders which rely on photope-
riod as well as other cues such as ambient temperature and food availability
to initiate breeding behavior ( Chemineau et al., 2008; Scaramuzzi and
Martin, 2008 ). In addition, adverse effects may derive from direct anthropo-
genic influences on mating systems and efficiency ( Lane et al., 2011 ) such
as occurs with the changing of habitats and phonologies (either by changing
the local environment or relocations) and increasing the presence of environ-
mental factors such as endocrine disruptors.
In summary, each livestock species has developed a distinct repertoire of
courtship, copulatory, and maternal behaviors to ensure optimal reproductive
success within its native environment. Those features of domestication which
reinforce these behaviors should lead to greater reproductive “success” than
those which are in conflict. Thus a better understanding of these behaviors
has practical considerations for reproductive management of captive and
domestic animals. The ensuing discussion will provide an overview of the
reproductive and maternal behaviors among different domestic animals,
emphasizing those aspects which are of evolutionary and genetic interest. As
there is a significant amount of relevant information available on domestic
cattle, this will be used to illustrate a number of the phenomena and princi-
ples involved.
LIVESTOCK REPRODUCTIVE BEHAVIOR
In general, livestock species are both polygynous and promiscuous. Most
evolved as prey animals (although some, such as swine, are both prey and
predator) and generally exist in social groups, which may be matriarchal or
patriarchal in nature. Females undergo estrous cycles in which there are
defined periods of mating. This combination of prey status, female estrus
and grouping has led to a variety of mating strategies.
Female sexual behavior in domestic animals has been classified into
categories of attractivity, proceptivity, and receptivity ( Beach, 1976 ). Here,
attractivity represents the female's passive ability to stimulate male interest,