Embryonic mortality is the loss of a pregnancy before 45 days, or the loss of the conceptus, from conception to the differentiation stage. Early embryonic mortality is defined as the loss of an embryo during the first 40 days of pregnancy, with day 0 being the day of ovulation or last breeding
1. Recommended Books
1. Veterinary obstetrics & genital diseases
by Stephen. J Robert.
2. Handbook of veterinary obstetrics
by Peter GG Jackson
3. Current Therapy in Theriogenology II
by David Morrow
4. Arthur's veterinary reproduction & obstetrics
by Geoffrey H. Arthur
3. Definitions
• Obstetrics: A branch of Veterinary medicine
which deals with the care of the dam, birth and
postpartum period.
OR
• Subject that specializes in the female before,
during and after parturition.
4. Continued
• Gynecology: a branch of medical science that
particularly deal with the reproductive issues in
female.
• Andrology: specially in human/vet. medicine that
specifically deals with the reproductive systems of
male focusing on reproduction dysfunction.
• Theriogenology: is a branch of veterinary medicine
that focuses on the reproductive system in
animals.
5. EEM
• Death of fertilized ovum or embryo upto the end
of implantation.
• Pregnancy wastages:
1) Embryonic mortality: Termination of pregnancy
before maternal recognition of pregnancy is called
EEM(estrus cycle length doesn't change)
2) LEM: Termination of pregnancy after maternal
recognition and is associated with the delay in
occurrence of estrus and called Late Embryonic
mortality
3) Fetal Mortality: when termination of pregnancy take
place beyond day 45 of gestation then it is called fetal
mortality
6. Continued
• Normally 25-40% EM in farm species & is regarded
as a normal process of eliminating the unfit
genotype.
(Genotype is the entire array of gene carried
by or the genetic constitution of an individual
with respect to any limited number of gene
under examination)
• In cattle EM take place between day 8-16 of the
estrus cycles.
7. Continued
• EM is a difficult problem to deal with , because
there is no single factor to manipulate so as to
decrease the incidence of EM or to improve the
survivability of embryo.
• So many factors to be managed like genetics,
nutrition, stress & animal health that can
contribute to decrease the incidence of EM.
8. Continued
• EM must be differentiated from fertilization failure.
• Fertilization rate 85 to 95 % in normal cows.
• It was concluded that when cows were managed to
get high fertility, still fertilization failure contribute
15% to reproductive wastage.
• While EM accounts for 25% of the remaining
reproductive wastage.
9. Causes/factors affecting EM
1) Genotypic factors:-
– Mostly the genotypic abnormalities will result in EM
within first 15 days of pregnancy. The presence of normal
complements of chro. is must be properly express.
– Sometime a lethal gene will be expressed which results
in ED within first 5 days of pregnancy
– Another genotypic abnormality contributing to ED is the
abnormal chromosome number, that result in abnormal
growth of embryo & usually death occur within 1st
trimester.
– Sometimes certain genes that are important for the
growth & development of the embryo, are not expressed
appropriately& ultimately EM take place.
10. Continued
2) Nutritional Factors:
– There is no clear cut scientific evidence demonstrating
a direct cause & effect relationship in embryo loss in
cattle.
– However Vitamin A/beta-carotene, selenium, & Cu
deficiency are all involved in the increased incidence
of embryo loss.
– As no experimental data is available to correlate the
effect of nutrition on embryo mortality, however
energy & protein play an important role in the
maintenance of pregnancy
11. Continued
– So it is essential for cows to be in a proper body
condition score in order to minimize EM rate.
– Adjust diet according to animal requirements.
• Gaining condition less EM
• Losing condition High EM
It has been documented that in dairy cow high intake of rumen
degradable protein may lead to ED. This effect may be mediated
through reduction in pH of uterine environment during the luteal
phase during which the embryo must grow
OR to say that it could increase BUN level or may change hormone
secretion such as P4 & these changes are toxic to embryo.
12. Continued
3) Asynchrony
– After fertilization, embryo cleavages at different rate &
sometime it mature earlier/delayed & dose not suit the
uterine environment & may become toxic for the embryo
that are out of phase, resulting in EM.
– Immunosupressive pregnancy specific protein EFP
presence in early embryo loss.
– Maternal recognition of pregnancy occur around 15 to 17
day of conception i.e. embryo secretes bCSP/bTP-1.
– This bTP-1, change the synthesis of PG & prevent
luteolysis from occurrence
– Now if embryo doesn't signal its presence adequately to
the mother, the mother continue to cycle.
13. Continued
4) Role of P4 & Estrogen:
– P4 is essential for pregnancy maintenance.
– If cow doesn't produce sufficient P4, pregnancy will be
lost.
– Imbalance b/w P4 &E2, embryo transport
accelerated/delayed, lead to EM.
– Two main reason for lack of enough P4 level
1. The life span of CL is short i.e. regression of CL occur before
the embryo has time to signal its presence through secreting
bTP-1
2. The life span of CLs is normal but secrete low level of P4
which cannot suppress the luteolytic effect of PG.
14. Continued
5. Infectious Agents:
a) Bacterial Agents:
- Corynebacterium pyogens is the most common bacteria
found in the uteri of cattle.
- The major cause of Endometritis.
- Also responsible for aborted embryo or fetus etc
- Campylobacter fetus (vibrio fetus) causes EM
- Brucella abortus (Bang’s disease)
b) Viral Agents:
- BHV-I is a group of virus abortion but also EM
15. Continued
6) Other factors include
- Rectal palpation
- Age
- Breed
- Effect of male
Heifer have high conception rate than cows because they don't have
any
(1) added stress of nursing calf.
(2) possibly of infection to the uterus in the previous parturition
through difficult birth or RFM etc.
There are two areas that the male can contribute to the incidence of EM
1. Genetic: when the male transmit the possible lethal gene or
abnormal chromosome number & some genetic mutation.
2. Bull infected with virus that can spread this infection through out
the herd. Through vaccination/medication we can control the
infection from spreading to the herd.
16. Continued
7) Overcrowding:
- The degree of placental development depends upon
the availability of space & blood supply within the
uterus.
- When high number of implantation so decrease in
vascular supply to each site & restrict placental
development.
- This causes high EM in cattle & sheep following twin
than single ovulation.
17. Continued
8) Thermal stress
- EM increases whenever the dam is exposed to
elevated ambient temperature.
- When fertilize ova, subjected to high temperature
either in vitro/vivo, became damage but still
continue to develop & only die during critical stages
of implantation.
- Apparently heat stress antagonizes the inhibitory
effect of embryo on the uterine secretion of PGF2α.
18. Continued
9) Immunological factor:
After insemination, cow come in contact with
sperm & embryonic antigen.
If immunosuppressive mechanisms are not
functioning properly, the Antibodies produces that
reduces fertility.
