Reproductive and Maternal Behavior of Livestock - Genetics and the Behavior of Domestic Animals - page 173

male ungulates apply urine to their coats during the breeding season; a prac-
tice which probably augments their biostimulatory ability (Izard, 1983).
Despite this, it is probable that non-olfactory cues, such as auditory or visual,
play either a complementary or synergistic role ( Delgadillo et al., 2009 ).
The enabling circumstances for this to occur include the novel introduc-
tion of the male(s) to transitional females, as is commonly exploited as a
management tool at the beginning of the breeding season. A similar phenom-
enon occurs with goats and it has been suggested that the “ram effect”
evolved as a strategy in wild ungulates to ensure synchrony of mating
( Delgadillo et al., 2009 ). It is now apparent that male “novelty” is more
important than prior isolation, and also that this effect is not restricted to
anovulatory females ( Delgadillo et al., 2009 ). Further, the effectiveness of
biostimulation is related to the sexual activity of the males involved
( Delgadillo et al., 2009; Perkins and Fitzgerald, 1994; Signoret et al., 1984 ).

REPRODUCTIVE BEHAVIOR IN SWINE
Wild pigs generally form small matriarchal herds containing one or more
sows and their young, with males living elsewhere and joining the herd for
breeding ( Signoret et al., 1975 ). Although feral swine reportedly show a
preference for breeding in the autumn, or fall, this is not generally evident in
domesticated animals ( Signoret et al., 1975 ). Sows will actively seek boars,
with both proestrous and estrous females being strongly attracted to the male
( Signoret, 1970 ).
Males, in turn, show little discrimination between estrus and nonestrous
females, often identifying receptive females by a process of trial and error
( Chenoweth, 1981 ). Despite this, mounting attempts are rarely made with anoes-
trous sows ( Tanida et al., 1989 ). Flehmen is generally not observed in boars. In
free-range systems, courtship is often lengthy, with the sow showing relatively
few overt signs of impending estrus. Immobility of the female is the most impor-
tant indication that she is in estrus, although she may show special interest in the
male, including attempts to mount him ( Signoret et al., 1975 ). Stimuli from the
male are, however, important in eliciting standing behavior in estrous females,
with both olfactory and vocal stimuli being important ( Chenoweth, 1981;
Signoret et al., 1975 ). The mating reaction of boars is stimulated by both visual
and tactile factors, and they will readily mount immobile objects resembling the
rear end of a female. Full erection of the fibroelastic penis generally occurs after
mounting is achieved and copulation time is often prolonged compared with cat-
tle and sheep ( Chenoweth, 1981; Signoret et al., 1975 ).

Male Reproductive Behavior
A female in late pro-estrus receives increased attention from the boar, who
will attempt to stay in close attendance while attempting nosings and