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
ABSTRACT
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. Out 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. Out
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.
INTRODUCTION
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
out 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 erection.
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 urethral pulses.
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 manual stimulation
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
Akhal- 1
(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 conditions 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 a
ur observations over twenty years,
together with recent observations of others, indicate that both stallions
and operators can be readily trained to use this method.
REFERENCES
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).
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