Yes, but does this keep them from getting into heaven?
Date: Sun, 27 Mar 94 13:07:39 PST
Subject: Yes, but does this keep them from getting into heaven?
Forwarded-by: bostic@vangogh.CS.Berkeley.EDU (Keith Bostic)
From: The Journal of Theriogenology, Vol.31 No.2, February 1989
Stallion Ejaculation Induced by Manual Stimulation of the Penis
by Jim Crump, Jr. and Julia Crump
Roanoke AI Laboratories, Inc.
8535 Martin Creek Road,
Roanoke, VA 24018
Received for publication: February 25, 1988
Accepted: November 21, 1988
This paper reports the use of a procedure for collection of semen from
stallions by manual stimulation of the penis while the stallion is standing.
Our use of this method with 18 stallions of various ages and types of semen
collection experience indicates that this method may be an efficient
alternative to traditional semen collection techniques using an artificial
vagina and stimulus mare or dummy mount mare. Our observations, together
with those of others who have tried the manual technique, suggest that both
animals and handlers can be readily trained to use this method. Limited data
suggests that semen samples obtained by manual stimulation are similar to
those obtained using an artificial vagina.
Key Words: equine, stallion, semen collection, artificial insemination
The authors wish to thank Drs. R.M. Kenny and Sue M. McDonnell of Hoffman
Center for Reproductive Studies, University of Pennsylvania School of
Veterinary Medicine, for assistance in preparation of this manuscript.
A number of methods, including condom, vaginal sponge and artificial vagina,
have been employed for collection of semen from stallions (1). Currently,
the most widely recommended technique is the artificial vagina with a mare
or dummy mount. Successful collection of semen using an artificial vagina
with the stallion standing on the ground was recently reported (2). Since
1965, we have employed an even simpler method of collecting semen from the
stallion using manual stimulation of the penis, and holding a disposable
plastic bag over the end of the penis to catch the ejaculate. This technique
gradually evolved during our first year of implementing artificial breeding
on a small, remote farm, where semen collection equipment was not readily
obtainable. Initially, we attempted to fashion a home-made Mississippi style
artificial vagina (3) using a latex rubber tube occluded at one end by two
sticks and foam rubber padding. While manipulating this flimsy device, we
found that manual pressure applied to the penis elicited pelvic thrusting
and ejaculation, even before the stallion mounted the mare. Accordingly, we
proceeded to collect semen from stallions by manual stimulation and by
substituting a plastic bag for the artificial vagina. We continued to use
this method and it remains our preferred technique for obtaining semen for
our artificial insemination and semen freezing programs.
MATERIALS AND METHODS
Plastic bags of various sizes are successfully employed. A bag should extend
8 to 12 in. up the shaft of the penis and be large enough for the glans
penis to fully engorge. It is important to use a bag made of material which
is not toxic to sperm. We presently use 6" x 10" polyethylene (1.5 mil) bags
(Bel-Art Products, Pequannock, NJ). In addition to the bag, we use a 500-ml
plastic squeeze bottle filled with warm water (48 to 52 C), which is used to
wash the penis and to warm the hand of the operator before manipulation.
The stallions is stimulated to achieve an erection, but is not allowed to
mount. Some horses will respond adequately to a mare or gelding presented at
a distance, or a brief glimpse of a mare or gelding walking past a doorway;
others respond adequately to a dummy mare; still others will respond in
their stalls to the operator rubbing the horse's chest, abdomen, flank or
thigh. We have also used an in vitro olfactory stimulus (the urine of an
estrous mare presented on a paper towel) to arouse a stallion for collection
of semen. This stimulus seems to work particularly well with young,
inexperienced stallions. We have found that intensely aroused stallions
often fail to respond favorably to manipulation. Therefore, our aim is
generally to present the least amount of stimulation to schieve and maintain
When erection is achieved, the penis is rinsed with warm water from the
squeeze bottle. This usually elicits some engorgement of the glans penis as
well as shallow pelvic thrusting. The plastic bag is then placed over the
shaft of the penis and secured with one hand placed proximally to to the
preputial ring. The other hand is placed over the glans penis with the thumb
behind the corona, as shown in figure 1. [Figure deleted here, unfortunately].
While applying firm pressure, the shaft and glans are gently
manipulated in a rhythmic fashion until the horse reponds with pelvic
thrusting. As the horse thrusts forward, the hands follow the thrusting
motion. Steady pressure is maintained on the shaft. Simultaneously, the
glans is rhythmically massaged with rotation motion, with the thumb
massaging the firm protuberance of the corpus cavernosum penis into the
glans penis. During initial training of a stallion, the position of the
hands as well as the rhythm and strength of the pressure applied on the
shaft and glans are varied depending on the response of the stallion, with
the goal of inducing deep pelvic thrusts and engorgement of the glans
characteristic of normal copulatory response. The stallion must be allowed
freedom to lower the head when thrusting. Ejaculatory pulses are easily
palpated and visualized. Premature release of pressure seems to interrupt
ejaculation in some stallions. In fact, s sperm rich portion of the
ejaculate may be obtained by releasing manual pressure after one or two
RESULTS AND DISCUSSION
Table 1 summarizes data on 18 stallions at our facility that were trained to
ejaculate in response to manual stimulation. The ejaculates obtained have
been used for insemination of mares, as fresh or processed semen (cooled for
24 to 36 h; 4,5).
Table 1. Summary of data on 18 stallions trained to ejaculate in repsonse to
Previous Number of Training Number Attempts for
Animal Age(a) Experience Sessions Required(b) Routine Collection(c)
Arabian 2 mo none 1 1 to 3
Arabian 3 mo none 2 1 to 3
Arabian 3 mo none 1 1 to 3
Arabian 3 mo none 1 1 to 3
Arabian 5 mo none 1 1 to 3
Arabian 5 mo none 1 1 to 3
Arabian 1.5 yr none 1 1 to 3
Arabian 1.5 yr none 1 1 to 3
Arabian 1.5 yr none 1 1 to 3
Arabian 2 yr natural 1 2(d)
Arabian 2 yr natural <3 1 to 3
Arabian 2 yr none 9 1 to 3
Arabian 3 yr natural 4 1 to 3
Arabian 4 yr none 1 1 to 3
Arabian 4 yr natural 1 1
Arabian 5 yr natural unsuccessful after 22
Arabian 12 yr natural <3 3 ejaculations 28 sessions
(a) Age at time of training
(b) The number of training sessions before successful ejaculation. Each
session consisted of several attempts to collect semen during an
approximately 15-min period.
(c) The number of attempts routinely required to collect semen. One
attempt consisted of placing the bag on the erect penis and
manipulating the penis.
(d) This stallion, over a period of 21 years, consistently would
ejaculate during the second attempt.
We have successfully employed this technique with novice and experienced
stallions. To better understand developmental changes in semen
characteristics and sexual behavior, we have trained several young colts to
semen collection procedures and have periodically examined ejaculates
throughout the first two years of life. The youngest stallion trained in
this collection technique was 2 mo old (Crump, unpublished studies). Other
stallions that were trained had previously been bred for many years by
natural service or artificial vagina. Training time does not seem to vary
systematically with the animal's experience. Generally, training is
accomplished within one or two sessions. Novice stallions have produced
ejaculates during the first attempt. Training time has varied from one to
several attempts for each of 9 sessions. One stallion was never successfully
trained after 22 training sessions over a three year period.
The manual stimulation technique was used successfully to collect semen from
one Arabian stallion for 21 yr, from 2 to 23 yr of age. The technique does
not appear to interfere with natural breeding or other collection
techniques, and many stallions with which we worked returned to or
alternated between natural service or artificial vagina programs.
In our various uses of semen, we have not detected any systematic
differences between ejaculates obtained by this manual method and by
traditional artificial vagina methods. For example, Table 2 summarizes nine
ejaculates obtained from one stallion over a period of 4 mo using four
variations of artificial vagina and manual stimulation methods. As shown,
there appear to be no systematic differences between samples obtained by the
various collection methods.
Table 2. Summary of 9 semen samples from a 12 yr Akhel-Teke stallion
obtained by three methods.
Collection Method of Volume ml Concen- Sperm
Date Interval Collection Semen Gel tration(a) Number(b) %TM(c)
Mar 31 not known AV/ground 20 0 283.0 5.7 75
Mar 31 1 hour AV/mare 65 2 94.0 6.1 75
Apr 16 7 days AV/mare 100 0 124.3 12.4 80
May 23 9 days AV/dummy 82 5 57.5 4.7 90
Jul 06 11 days AV/dummy 65 12 95.0 6.2 85
Jul 07 32 hours AV/dummy 68 4 56.0 3.8 90
Jul 10 2 days AV/dummy 56 5 146.8 8.2 85
Jul 12 2 days Manual 60 0 104.0 6.2 80
Jul 14 2 days Manual 63 5 124.0 7.8 80
(a) (10e6 sperm/ml)
(b) Total number or sperm x 10e9
(c) Visual estimate of percent total motility
Some stallions stop thrusing before ejaculating, or they may achieve
engorgement and appear to be near ejaculating, but stop just before. These
animals appear to become distracted or over-aroused during collection. In
our experience, these problems can often be avoided by providing the minimum
stimulus to achieve response. The stallion may, for example, become
distracted if he is too near an estrous mare during manipulation. In some
instances, an extremely stimulated stallion can be induced to ejaculate
simply by applying pressure to only the glans penis.
Most stallions readily become conditioned to this semen collection procedure.
They appear to associate breeding with the operator and the plastic bag.
Once trained, they often appear more attentive to the operator and the
plastic bag than to a mare, much the same as stallions that are trained to
an artificial vagina and dummy mare become conditioned to those breeding
stimuli. One stallion we worked with routinely achieved erection in the
stall when the operator approached with the plastic bag, and with manual
stimulation, he ejaculated (without the stimulus of a mare or of an
olfactory stimulus). In apparent anticipation of collection, two of our
stallions consistently backed away from the stimulus mare toward the
operator who was crinkling the plastic bag. Although we routinely use a
stimulus mare, stallions experienced with this technique often require less
stimulation from the mare thatn for traditional collection methods.
With minor modifications, this technique has recently been employed with
pony stallions at the University of Pennsylvania (McDonnell, personal
communication, 1987), where 10 stallions, subjects of a semen study, were
readily trained for the collection of semen with a plastic bag and manual
stimulation. Five of these 10 stallions consistently responded quickly and
ejaculated while standing; the remaining 5 responded with less vigor and
were allowed to mount a mare for collection, in which case manual
stimulation was performed in place of an artificial vagina. In addition, a
warm (45 to 50 C) wet towel compress was added to provide additional
stimulation of the glans penis when necessary. All stallions successfully
ejaculated within one or two attempts, and continued to be managed in this
manner without any complications. Throughout the 3-mo study, semen samples
were collected two to three times a week; usually less than 1 h was required
to obtain semen samples from the 10 stallions. In this study, the stimulus
mare was tethered, so collections were accomplished by one stallion handler
and one operator. In similar work (McDonnell, personal communication),
collections were made from stallions tethered in their stalls with a
stimulus mare tethered nearby. This arrangement permitted one person to
conduct the collection. The breeding history of the stallions varied: some
had been bred naturally and some had previously been trained to artificial
vagina collection of semen. However, all animals readily responded and
became conditioned to the manual stimulation method. Subsequently, several
student operators have successfully collected semen from these ponies even
in their first attempt to employ the technique.
The manual stimulation technique offers several distinct advantages over
traditional semen collection methods (artificial vagina on a mount mare).
These include 1) markedly reduced collection time and minimal preparation
and clean-up time; 2) cleaner samples (plastic bag contacts only lower
portion of the shaft of the penis), no lubricating jelly is required; 3)
disposable materials, reduced risk of infection; 4) inexpensive materials;
5) heat damage to sperm from contact with artificial vagina reduced; 6)
places less physical stress on stallions; 7) allows several ejaculates in
quick succession (one stallion produced six ejaculated in less than 20
minutes, another produced three ejaculates in 6 min); 7) it is possible to
obtain just the sperm-rich portion of the ejaculate; 8) generally requires
fewer personnel; and 9) does not always require a stimulus mare.
While we have preferred to train stallions to ejaculate while standing on
the ground, manual stimulation with a plastic bag can be substituted for the
artificial vagina with the stallion mounted on a mare or dummy mount.
Potential disadvantages of this technique are that 1) a stallion and
operator may require more training than is necessary when an artificial
vagina and mount mare technique is used 2) large, tall horses may thrust
with enough force to unbalance or knock down the handler, and 3) with tall
horses, the operator may be at risk of injury should the horse kick during
the procedure. In addition, it is difficult to adequately manipulate the
larger glans penis typical or large, tall horses.
We have found collection of semen from stallions by manual stimulation of
the penis to be a convenient and efficient technique. It involves our
observations over twenty years, together with recent observations of others,
indicate that both stallions and operators can be readily trained to use
1. Kenny, R.M., Hurtgen, J.P., Pierson, R., Witherspoon, D. and Simons,J.
Clinical fertility evaluation of the stallion. Hastings, NE: Society
for Theriogenology (1983)
2. Schumacher, J. and Riddell, M.G. Collection of stallion semen without
a mount. Theriogenology 26:245-250 (1986)
3. Berliner, V. Horses and jackstock, In: Perry, E.J. (ed.): The
Artificial Insemination of Farm Animals. Rutgers University Press,
New Brunswick, NJ, 1960, p.221.
4. Douglas-Hamilton, D.H., Osol, R., Osol, G. and Driscoll D., Noble, H.
A field study of the fertility of transported equine semen.
Theriogenology 22:291-304 (1984).
5. Cristanelli, M.J., Amann, R.P., Squires, E.L., and Pickett, B.W.
Effects of egg yolk and glycerol levels in lactose-EDTA-EGG yolk
extender on the motility of frozen-thawed stallion spermatazoa.
Theriogenology 24:681-686 (1985).
© 1994 Peter Langston