1 Introduction, Synonyms, Definition, Prevalence, Economic Importance, Etiology and Classification

Transcript

Dear and respected veterinarians.

We are going to see about the Repeat Breeding syndrome in cows. It is an important form of infertility, leading to heavy economic loss to the Farmers. How it causes economic loss? Because the number of inseminations will be more, the calving to conception interval will be more, so animals will be repeatedly coming to heat and it is not conceiving, so that may lead to heavy economic loss to the farming community. So, if you would know about these, Repeat Breeding syndrome very well, you can treat the case very easily in the field condition so that farmers’ economy can be improved. With that idea, we are going to see about a repeat breeding syndrome in cows.

The Synonyms of the repeat breeding cows are Cyclical non-breeders, Repeaters, and Repeat breeders.

There is a classical Definition for repeat breeding syndrome. Repeat breeder is the one that has been bred two or more times with fertile semen but failed to conceive, which they earned it as normal or nearly normal estrous cycles and estrous periods along with the following Characteristics:

It should have a normal estrous cycle length of 21 days.

It should be free from palpable abnormalities of the genital tract. The genital tract should be free from any palpable abnormalities.

It should have normal vaginal discharge during the estrous period.

The animal must be in positive energy balance. It should be at least calved once, and

It should be less than 10 years old

One important point to be noted here is, it should be at least calved once. Here we are including heifer also nowadays, but as per the classical definition, the repeat breeder must be at least once calved.

When we talk about the Prevalence of the conditions in cows and buffaloes, crossbred animals have affected the percentage of (17.57% ), Buffaloes have the problem of 12.74%, Indigenous cows are less commonly affected, it is 8.64%, 30.4% of the cattle and buffaloes were culled for mainly infertility problem, among the various infertility problem, repeat breeder alone costs about 18 to 20% of the infertility problem. That is why this condition has more importance and relevance to be discussed here.

The Importance in Economy, repeat breeder causes very heavy economic loss as I told you earlier, the cost involved is a Breeding cost, Treatment cost, Feeding cost, and Labor cost. Suppose if an animal is not conceiving a single day, the maintenance cost is about to ₹200, that is the loss is ₹200 per day, nowadays. If one cycle is lost, 21* 200, so ₹4200 is a loss to the farmer. Repeat better even after two or three cycles, it is not getting conceived, that is why the basic economic losses are caused by this delay in conception due to repeat breeding syndrome. Now we are switching over to the Etiology of Repeat breeders:

There are two types of classifications, one is by Casida and co-workers and another one is by Roberts and Zemjanis. So first the Casida co-workers classified the repeat breeding syndrome as fertilization failure and the early embryonic death. So based on this classification only we are going to discuss Etiology in the future.

Another classification is the Zemjanis and Roberts classification, which includes there are five types of etiological factors, one is Congenital or genetic anatomical defects of the reproductive tract in cows. The second is Congenital or genetic acquired defects of sperm, ovum, and zygote. Third is Infectious or traumatic inflammatory causes, fourth is Endocrine dysfunction, fifth is Managemental and nutritional deficiencies causing repeat breeding syndrome. So, these are the etiological factors classifications.

Now we will go one by one, Fertilization failure. Actually, Fertilization failure constitutes 15% of reproductive wastage.

Ovulatory defects: Ovulation occurs 12 to 14 hours after the end of estrum in cattle. This is important for the ovum to get fertilized with the presence of spermatozoa already deposited in the genital tract, you all know well. Suppose any delay in ovulation, you’ve already deposited the semen, so all the spermatozoa will die by the time ovum is coming. So delayed ovulation is one of the reasons for fertilization failure. Another reason is Anovulation, sometimes animals may come to heat or estrous and the follicular development will be there, animals will come to heat, but there may not be Ovulation. So, all the spermatozoa which are waiting in the fallopian tube may not involve in fertilization, so that may end up in fertilization failure. Another reason for the ovulatory defect is cystic ovarian degeneration, follicles may develop, they will persist in the ovary, ovulation may not occur, which may lead to ovulatory defect and fertilization failure. So look at this (showing picture), this is the fully matured follicle, it should rupture and produce ovum if any delay or failure to rupture or retention of the follicle in the form of a cystic ovarian degeneration leads to repeat breeding syndrome.

Second is the Ageing of the Ovum; aged ovum: Suppose ovulation takes place, you are inseminating too late when we will inseminate 12 hours after the onset of estrum, we are going to inseminate the animal, that is the classical point,12 hours after the onset of estrous, i.e, from mid estrum to late estrum we have to inseminate the cow. Suppose you are inseminating after the end of the estrum but after the end of the estrum the sperm has to undergo capacitation reactions, it is not getting ready for fertilization so due to this phenomenon, Ovum is aged. so there may not be any fertilization occurring in the aged ovum.

Defective Ovum: sometimes what will happen is there will be a micro-ovum, macro-ovum, or failure of extrusion of second polar body, so all these causes defect in the Ovum, that also leads to fertilization failure.

Next to failure of male and female gamete union: that may end up in fertilization failure. Also, sometimes unilateral hydrosalpinx, bilateral hydrosalpinx, severe endometritis, all these things will cause the failure of union of male and female gametes.

I told already the Ovaro-bursal adhesions and Tubal obstructions are the major problems causing the fertilization failure.

Stress: stress also, animals are exposed to various types of stress, For example, excessive heat, excessive cold, fear, shyness, all these causes stress, threatening by the owner, everything will cause stress and may lead to improper fertilization or improper movements of gametes in the genital tract and they end up in fertilization failure.

Next, sometimes Antisperm, antibodies are formed in the female genital tract. Because you know very well that, sperm is an antigen, so to this antigen, the antibody will be produced in the genital tract, especially in the cervix. But in the natural cervix, the semen is deposited in the vagina, when the sperm reaches from the vagina to the cervix, these Antisperm antibodies present in the cervix or cervical mucus, will mask the moment of the protozoa, that will end up in fertilization failure. So Antisperm antibody production is there. To bypass this in artificial insemination, we are depositing the semen in the body of the uterus, you know. So, in one way we are passing this barrier of cervical mucus and depositing the semen.

We are continuing with Fertilization failure. As I already told Segmental aplasia.

Segmental aplasia: look at this picture, this is the uterus unicorns, one side of the uterus is not developing,

Hydrosalpinx: this is hydrosalpinx, you look at this fallopian tube is filled with fluid, and

Ovaro-bursal adhesions: here Ovaro-bursal adhesions, you cannot separate the ovary from the rest of the bursal. So, all these leads to fertilization failure because they prevent the union of male and female gametes,

Anti-sperm antibodies: here also you look at this anti-sperm antibody production in the cervical mucus that will prevent the movement of the spermatozoa, masks the moment of the spermatozoa, it will cause the head-to-head attachment or tail to tail attachment of the spermatozoa, so that will end up in fertilization failure.

Dear Vets, we have seen so far various Etiological factors involved in causing Fertilization failure that leads to Repeat Breeding syndrome in cows and buffaloes. So, we will stop here. We will continue with the early embryonic mortality in the next class.