Vle CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. II

Aisu from 8 cases, in which pregnancy does not exist
any more, = in 5 the death occured before the end of
the 2=d month. In 2 cases it occured between 60-th and
30~th da¥, and in one probably after 84 days of pre-
gnancy. In 11 cases /6% of mares/ the e.m. occured in
nursing mares; from these 10 concelved in the foal and
1 in post foal heats. 2 cases occured in maiden mares,
and 3 in previously barren. In 6 mares the infection of
the uterus was found. The average age of the involved
mares was 7,7 years. If the 19-years o0ld mare, which
gave 13 foals, and mares with uterine infections will
be excluded, the average age will come down to 7 years.
Whereas the average age of mares of the stud varied
from 8,5 up to 9 years. This means, that not bacterial
e.m. occurs in younger mares.

The infections, in 5 caused by beta-hemolytic stre-
ptococci, occured chiefly in mares with unsufficient
closing of the vulva, as either the effect of excessive
distenstion or rupture of it duri parturition.

With the exception of 3 maresnﬁincluding the 19
years old/ all other, in which embryonic death cccured,
did not belong to the group of fertile animals, giving
foals unregularly.

DISCUSSION. The % of e.m. in the observed stud makes
T,1%. If the cases caused by the infections and the not
nursing mares will be excluded, % of mortality, favou-
red by lactation, will come down to 3,2. Recently Merkt

found, that this %, occuring in 2-nd month of pre=-
gnancy, can be as high as 17 %. Certainly examination
for early pregnancy performed only twice could not re-
veal all cases of e.m. in observed stud. But, as the
service records indicated, this fact could not lower
this precentage as far, as about 35:58% Undoubtedly,
part of embryos does die before 3 weeks of pPregnancy,
what can not be revealed by clinical examination.

As 1t was mentioned above, most mares, in which
€.m. occured, gave theilr offsprings not regularly. It
seems, therefore, that one of the factors, which do
ralse the embryonic mortality, is the genetically con-
ditioned low fertility, which may be caused by inbree-
ding, and the expression of whicﬁ is the embryonic
mortality

REFERENCES

1. Hoppe R., Domariski E., Dobrowolska A. 1956. Proc.
III. Intern. Congress Anim. Reprod .II. 83.
2. Merkt H. 1967. Vet. Bul. 37.1.427.

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