2 Early Embryonic Mortality

Transcript

Dear Veterinarians, so far, we have seen various factors involved in causing Fertilization failure in cows and buffaloes, that lead to Repeat breeding syndrome. We have seen in yesterday’s class all these factors. In today’s class, we are continuing with the Early Embryonic Death in cows and buffaloes, it is the greatest problem causing repeat breeding syndrome in cattle. Fertilization is not the matter; the Embryonic development is the matter for their successful fertility that we will continue today. So, it also constitutes about 25% of the reproductive wastage, I told Fertilizing failure constitutes about 15% but now the recent literature if you see the fertilization is not the matter, almost in 95% of the animals’ fertilization takes place, further development of the embryo is the crucial factor in determining the fertility of the cows and buffaloes. So, in our infertility problems, dealing with Early Embryonic Death is more important than Fertilization failure. It constitutes about 25% of reproductive wastage.

What are all the factors causing Early Embryonic Death:

One is Chromosomal Aberrations, this Chromosomal aberration is seemed to be very common in Guernsey breeds, any chromosomal defect in the Ovum or in the Sperm that may cause the death of the embryo subsequent to the fertilization. In the case of cows 1/29 Robertsonian translocations cause Early Embryonic Death, likewise the sperm defect also, that is any defect in the chromosomes of sperm also causes embryonic mortality. Ovum also causes embryonic mortality.

Aged Ovum: What will happen? Ovum will be released, delayed insemination, after the release of Ovum, may cause penetration of the ovum by more number of spermatozoa, when the ovum becomes aged, the membrane integrity of the zona pellucida is lost, so the membrane integrity will be lost, it will allow more number of sperm to enter into the ovum, therefore Early Embryonic Death occurs in the fertilized Ovum due to more number of chromosomes. Actually, half of the chromosomes are from the male gamete and half of the chromosome from the female gamete forms the Zygote, suppose more sperms enter into the ovum that may lead to the Early Embryonic Death.

Polygyny: During the Fertilization process, Ovum matures followed by Sperm matures then ovum and sperm encounter, these are the steps in the fertilization. But ovum maturation is completed at the time after the time of sperm entry only, ovum released as secondary oocyte i.e., the ovum is released at the time of ovulation as secondary oocyte in cows and buffaloes. Then it continues to mature, when the sperm penetrates, after the penetration second polar body will be extruded, which completes the ovum maturation. But when the second polar body is not extruded at the time of fertilization, then that may end up in a Polygyny. Polygyny means failure of extrusion of second polar body. So, the second polar body will be extruded in a normal course of fertilization, if it is not extruded, that may end up in Polygyny, which in turn will lead to Early Embryonic Death. Why I am telling you about all these etiological factors? If you know this etiological factor only as a field veterinarian, quite interestingly you can treat the animals by knowing the cause, by diagnosing the cause of the repeat breeder.

The next important cause is Specific infections: But if you take Specific infections after the introduction of Artificial Insemination, these etiological factors have minor significance because the bull is screened for Trichomoniasis, Vibriosis, Brucellosis, IBR, IPV, Tuberculosis, and Johne’s disease. So, the semen is prepared or semen is obtained from the genetically proven and bull which is free from infection. So always it is better to use Artificial Insemination to avoid Specific Infections. What are the specific infections in the cattle: It includes Trichomoniasis, Vibriosis, Brucellosis, Tuberculosis, Johne’s disease, all these are Specific infections. These Trichomoniasis, Vibriosis, Campylobacterosis, or Brucellosis may cause early Embryonic death. Many of us think these are the agents responsible for abortion, they are not only responsible for abortion but also responsible for embryonic death.

Next is Non-specific Uterine infections: if you take any animal, the vagina will have all our types of organisms’ Saprophytic organisms, including Streptococcus, Staphylococcus, E-Coli, all these infections will be there in the vagina. When the animals’ resistance goes down, these organisms take the upper hand, and it causes genital infections. Clearly note down this, because always the female genital system, especially the vagina, is contaminated because it has a connection with the environment, and because of these organisms present in the vagina, they may flare up our hit multiplied when the animals’ resistance goes down, so this nonspecific uterine infection also many times causes Early Embryonic Death.

There are 7 important micro-minerals that are necessary for successful reproduction, including Selenium, Copper, Zinc, Iron, Cobalt, Magnesium, Manganese is the seven minerals that are necessary for successful reproduction, and they act as a coenzyme for the production of hormones. That is why very, very important mineral mixer supplementation for infertile animals. Next is Environmental factors, so Environment also plays a vital role in causing the repeat breeding syndrome, high temperature, high humidity, all these environmental factors may cause heavy rain, then flood, natural calamities, all these may cause an impact on the fertility of the animal.

The next important thing, which can be avoided by any Veterinarian, Semen contaminated with infectious agents, we should get semen from approved semen stations or government organizations. So, the Semen, you should ensure it is free from any infectious agents, otherwise, the spread of infections will be more.

Then at the time of AI, we should concentrate on clear hygienic AI, otherwise, any contamination during AI may lead to repeat breeding syndrome. Not only that, it will further aggravate the condition by causing uterine infection.

Next is Oxidative stress. Due to the metabolic activity, there will be free oxygen radicals circulating in the blood. These free oxygen radicals are harmful to the embryo, so that may cause Early Embryonic Death.

Hot sunlight: If the animal, after the insemination, is exposed to heavy or high environmental temperature, under the hot sun, that may cause embryonic mortality. That is why you used to advise after one or two days of insemination, animals must be kept in a shed, so that the environmental temperature may not increase the body temperature. If the body temperature of the animal is increased due to the environmental temperature, it may cause embryonic death. Next is Endocrine Dysfunction: Endocrine dysfunction, any hormonal deficiency, especially progesterone deficiency or LH deficiency, any form of deficiency of hormones may cause a repeat breeding syndrome.

Then another very important is Sub-clinical endometritis: This animal will have clear discharge, but it doesn’t mean the uterus is free from infection, many books say that uterine infection without any clear evidence may cause prevention of implantation, that is why it is leading to Embryonic mortality, and this is a thing you have to know Sub-clinical endometritis is another major important cause for repeat breeding syndrome under field condition.

Dear field veterinarians. So far, we have discussed Fertilization Failure and Early Embryonic Death in cows and buffaloes, which lead to a Repeat breeding syndrome in these animals. We will stop here and will continue with the diagnosis of repeat breeding syndrome in the subsequent class.

Thank you!