Darling, Kjersten D.V.M, and James
M. Griffin, M.D. Veterinary Guide to Horse Breeding. New York: Howell
Book House, 1999.
Georgi, R. P., Et al. The Horse.
2nd ed. New York: W. H. Freeman and Company, 1990.
Lose, M. Phyllis V.M.D, Blessed
are the Brood Mares. New York: Macmillan Publishing CO., Inc., 1978.
Senger, P.L. Ph.D., Pathways to Pregnancy and
Parturition. Pullman: Current Conceptions, Inc., 1999.
Vale, M. M., D.V.M., and Don M.
Wagoner, eds. The Veterinary Encyclopedia for Horsemen. Grand Prairie:
Equine Research, Inc., 1977.
Age
at puberty:
12 to 24 months Classification of uterine anatomy: Bicornuate
Average
number of offspring: 1 foal Normal size of follicle at
ovulation: 35 to 60 mm
Cycle
length: 21
to 23 day (14 days diestrus, 7 days estrus)
Determining
pregnancy:
failure to come back in heat (17-21d), rectal palpation (18-20d), ultrasound
(14-18d), Equine chorionic gonadotropin (50d) and progesterone (16d) tests
Gestation
length: 335
to 340 days (colts are often carried 2 to 7 days longer than fillies)
Reproductive
senescence:
Mares over fifteen often have lower conception rates then younger mares but
mares can have foals well into there twenties with proper care.
Type
of estrous cycle: seasonal polyestrus (long day breeders)
Type
of placental attachment: Diffuse
The Ampullary-isthmic junction is the control point that stops non-fertilized oocytes from passing in to the uterus.
The Ovum travels to the uterus approximately 6 days after fertilization
The cervix relaxes and becomes softer during estrus and more sensitive, stimulations causes muscular contractions; the cervix is not a barrier to sperm and may extend partially into the vagina.
The infundibulum covers the ovary so to catch the ova as it ovulates.
The
placenta is formed by 3 membranes the chorion, allantois and the amnion
and at least six layers of tissue separate the mare’s blood from the fetus’s
blood.
Age
at puberty:
12 to 19 months Length of spermatogenic
cycle: 54 day
Classification
of penis anatomy type: Cavernosum penis
Age
that maximum reproductive potential is reached: 6 years
Ejaculate
volume (gel free): 20mL to 300mL (average 50mL to 60mL)
Number
of ejaculations per day: up to 5 fertile ejaculations
The
scrotum:
less pendulous then the bull or ram,
Number
of sperm considered critical for fertilization: 200 million sperm per
ejaculation
Sperm
concentration:
10 to 15 billion sperm per ejaculation
Seamen
delivery:
at the cervix and under pressure such that it travels through to the uterus:
delivered in 8 seminal jets with the first three jets containing 80 percent of
the sperm.
Seamen
storage:
seamen extenders should be added to seamen collected for A.I. purposes so that
the ration is 25 to 50 million sperm per mL. Seamen can be stored in the dark
for up to 12 hours at room temperature. Seamen can be cooled to temperatures
around 4 to 8 °C to for periods of 48 hours but sperm motility is reduced the longer
the sperm remains cooled.