Vie CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. Il

AN INDUCED CYSTIC OVARIAN CONDITION
IN THE MARE

J.M. Bowen, B. Vet. Med., M.R.C.V.S.

of '"Westways", Park Street, Thaxted, Essex

One of the problems posed when trying to collect
from a stallion is to find a suitable mare in oestrus.
While it is possible to train mares to stand for such
collections, and there are a variety of dummies available
for this purpose, neither alternative is a satisfactory
substitute.

It would be better to have a mare in a continuing
state of oestrus, without the disadvantages of the true
nyphomanical mare. Not only does the presence of a
mare that is in use greatly facilitate collecting, but
it also has a significant effect on the ejaculate
collected.

In 1966 an attempt was made to synchronise oestrus
in a group of mares using one of the progestogen group
of drugs, namely Melengestrol Acetate fed at the rate
of 0.5 mg and 1.0 mg daily to two groups of three mares
respectively. Treatment was started on March 7th. By
March 9th two mares were exhibiting signs of oestrus
but would not stand for the stallion. Rectal palpation
showed that there was follicular development taking
place in spite of the progestogen. By March 15th two
mares would stand to the stallion and two were in
proestrus. At this point the attempt to synchronise
oestrus by feeding Melengestrol Acetate was discontinued,
as at the above dose rate it was obviously not having
the effect we desired. All the mares eventually showed
signs of cystic ovarian disease. As most of the mares
in the experiment were maiden mares it was rather
surprising to see how well they would stand for the
stallion and so I decided to use one mare to collect
from a young stallion. This stallion was collected
from regularly over a period of four weeks using this
same mare and each time she was presented with the
stallion she exhibited all the sexual receptive signs
of full oestrus.

Subsequently, when we needed to collect from some
young stallions (Skinner and Bowen) we used Melengestrol

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