This study was designed to assess the determinants of dominance and preferred association in light breed mares and foals. Similar studies have previously been
Ž conducted to assess the determinants of dominance in draft horses Ellard and Crowell-
. Ž
. Davis, 1989; Araba and Crowell-Davis, 1994 and ponies Asa et al., 1979 . Studies
involving light breed horses have been of Thoroughbreds or groups of various breeds Ž
. Houpt and Wolski, 1980; Houpt et al., 1978 and were not conducted in the field.
Instead, these studies determined dominance relationships from the results of paired feeding tests. The following study used observations of spontaneous behavior in the field
to assess dominance and preferred associate relationships among light breed mares and foals. The following hypotheses were tested:
I. The dominance rank of the foal in the foal herd correlates with that of its dam in the mare herd, but not with its order of birth into the herd.
Ž .
II. The dominance rank of the foal correlates with its size height or weight , but not gender.
III. Foals associate most often with the foal of their dam’s most preferred associate. IV. The foal’s most preferred associate is more likely to be of the same gender than of
the opposite gender. V. Foals are more likely to aggress toward other foals than toward their most
preferred associate per unit time spent near them. VI. The rank of the foal positively correlates with its rate of giving aggression.
VII. The rank of the foal is negatively correlated with the rate at which its aggression is ignored.
VIII. Males and females differ in the type of aggression they most often display toward other foals.
2. Subjects and study site
The subjects of this study were 14 light breed mares and their foals. The herd consisted of 10 Quarter horses, two Arabians, one Hanovarian, and one Saddlebred.
Among the foals there were several fillies, four colts, two early pre-pubertal castrates Ž
. EPC and one pre-pubertal castrate. The early pre-pubertal castrates were gelded at
approximately 1 month of age. The pre-pubertal castrate was gelded at approximately 4 months of age. The mares existed together as a herd for almost 12 months prior to the
birth of the first foal. Four to six weeks before a mare’s expected foaling date each mare was moved to an individual foaling pen. The foaling season started March 16 and lasted
Ž .
until the birth of the last foal on May 28, 1996 Table 1 . Observations were conducted at the Smithonia Breeding Center in Colbert, GA. The
Ž herd was maintained on a 10-ha pasture. The pasture is composed of fescue Festuca
. Ž
. Ž
sp. , common bermudagress Cynodon dactylon , coastal bermudabrass Cynodon dacty- .
Ž .
lon L. Pers. and rye grass Lolium perenne . Observations were also conducted in a small paddock to which mares were brought daily. Mares and foals were brought to the
Ž .
small paddock 0.11 ha for mares to be rebred and for foals to be weighed and
Table 1 Subject’s number, gender, birthdate and weaning date
Subject number Gender
Birthdate Weaning date
06F Male
May 1, 1996 September 27, 1996
07F Female
April 20, 1996 September 20, 1996
12F Female
April 6, 1996 September 11, 1996
18F Female
April 11, 1996 August 24, 1996
24F Female
April 2, 1996 August 26, 1996
30F Male
April 11, 1996 September 11, 1996
34F Male
May 28, 1996 August 26, 1996
35F Male
March 18, 1996 August 19, 1996
45F Male
April 6, 1996 September 27, 1996
53F Female
April 30, 1996 September 11, 1996
57F Male
April 22, 1996 September 27, 1996
00F Female
April 27, 1996 September 27, 1996
37F Male
April 22, 1996 September 20, 1996
100F Female
March 16, 1996 August 2, 1996
measured. The small paddock consisted of a mostly dirt substrate. Mares and foals were brought from the large field to the small paddock approximately five times a week until
early July. After this time, they were brought to the small paddock one to two times a week. Mares and foals would spend several hours in the paddock each time they were
housed there.
Foals were weaned at approximately 4 months of age. Therefore, foals were not weaned at the same time, though they were sometimes weaned in groups of two or three.
Throughout the weaning process, weaned foals remained in the pasture with unweaned foals and their mothers. The dams of weaned foals were moved to another pasture on the
premises. The practice of weaning foals at 4 months of age is a standard practice at the Smithonia Breeding Center.
Ž The caretakers distributed grain twice daily between 0830 and 0900 and between
. 1700 and 1730 in buckets approximately 3 m apart. Throughout the study there were
Ž .
Ž .
between 11 and 18 buckets from which 14 post-weaning to 28 pre-weaning animals fed. Distribution of food was not under the researcher’s control.
3. Methods
