Repeat Breeding Syndrome

Repeat breeding syndrome is one of the most important problems the veterinarian faces in the field. The cows are apparently normal and give no clue to the cause.

Farmers also get vexed to bring the animal repeatedly without knowing the future prospects of the animal.

A repeat breeder cow is defined as one that:

• Has had three or more unsuccessful services
• Has normal estrous cycles with approximately 21 days intervals
• Is free from palpable abnormalities
• Shows no abnormal vaginal discharges
• Has calved atleast once before
• Is less than 10 years old

This definition is quite restrictive and may not fit in all cases.

The normal incidence of fertility based on a conception rate of 50%, would be 50% after the first service, 75% after the second and 87% after the third.

Since the conception rate decreases as the number of services increases there would be atleast about 15–20% of animals as repeat breeders. If the conception rate is lower, the incidence of repeat breeders would be higher proportionately.

Etiology

All the major causes can be grouped into two categories by Casida et al. as:

• Fertilization failure
• Early embryonic death

Repeat breeding syndrome is classified by Zemjanis as:

• Congenital or gentic anatomical defects of genital tract.
• Congenital, genetic or acquired defects of ova, Spermatozoa or early zygote.
• Infectious or traumatic inflammatory processes.
• Endocrine dysfunctions.
• Managerial and nutritional deficiencies.

(1) Fertilization Failure

Fertilization failure accounts for about 15% of reproductive wastage in normal cows. In repeat breeder cows the fertilization failure may be higher at 28-44%.

Abnormalities

• Failure of ovulation.
• Delayed ovulation.
• Both conditions are due to deficient LH release.

Defects of the Ovum

• Defective ovum.
• Ageing of ovum-ova are viable for only a few hours.

Inability of the Sperm to Fertilize a Viable Ovum

• Fertility differences of bulls.
• High sperm abnormalities.
• Low individual motility.
• Low sperm concentration..
• Inflammatory conditions of genital tract.
• Very early AI or ageing of sperms.

Inability of Gametes to Reach One Another

• Anatomical defects of genital tract both congenital and acquired.
• Segmental aplasia.
• Various affections of oviduct leading to obstruction.
• Failure of ova pick-up.
• DUMPS-Deficiency of Uridine Monophosphate Syntetase which is an autosomal recessive gene that results in fetal death in first 2 months of gestation.
• 1/29 Robertsonia translocation, chromosomal berration, abnormal karyotype such as XXX is associated with infertility in Holteins.

(2) Early Embryonic Death

Embryo loss accounts for the major portion (25%) of the reproductive wastage.

Time of Embryo Death

• Major portion of the embryo death occurs gradually between days 8 and 19 after breeding.
• Most embryo death occurs before the critical state of pregnancy recognition i.e. the cow will return to estrus at the normal 18-25 days interval.
• Embryonic deaths occurring at 8-16 days after breeding usually do not affect the normal cycle length of about 18-24 days.
• Embryonic deaths occurring at 16-25 days often result in longer periods between service and next estrus.

Etiology

Cytogenic Abnormalities

• Critical requirement for the embryo survival is the presence of a normal complement of chromosomes.
• Chromosomal aberrations-abnormal karyotypes-play some unquantified role in early embryo loss.

Unfavourable Uterine Environment

Egg transfer experiments indicate that best pregnancy rates are obtained if synchronous transfer is carried out.

Uterine environment is:

• Enables the spermatozoa to ascend.
• Provides adequate nutrients for different stages of embryonic development.
• Maintains an appropriate milieu.
• Fulfils immunologic requirement s(both immunosuppressive and antibacterial requirement).

Uterine environment can be affected by:

• Hormonal imbalance
• Infections-endometritis.
• Nutrition
• Environmental stress

Hormonal Imbalance

• There are conflicting reports this cause.
• Some indicate that in repeat breeder cows the administration of progesterone tends to increase the pregnancy rate.
• Administration of hCG during the luteal phase to induce steroidogenesis by the corpus luteum is an alternative approach but has also given mixed response.

Non-Specific Uterine Infections

• The presence of a non-specific uterine infection or endometritis around the time of service was not an important cause of infertility in the cows which were free of clinically detectable uterine disease.
• Only C. pyogenes was consistently associated with endometrial lesions. Severity and their effect on fertility were mainly determined by the duration of the infections.
• The bacteria may interfere with fertility by:
  • Directly killing the gametes or conceptus.
  • Changing the uterine milk.
  • Causing endometritis (toxic products, luteolysis).
  • Producing chronic histologic lesions.

Specific Uterine Infections

Organisms which cause early embryonic death are:

• Trichomonas fetus
• Campylobacter fetus
• Brucella abortus
• IBR-IPV

Nutritional Causes

• Extremes of nutrition are detrimental to the survival of embryo.
• Deficiencies of wide range of specific nutrients have been implicated in poor reproductive performance. Particularly selenium and Vit. A were reported to cause early embryotic death.
• A very high plane of nutrition also leads to embryonic death.
• Extended period of feeding estrogenic forages affects the embryo survival.

Environmental Stress

• The temperature of the uterus during the first week after AI has been shown to be important.
• Sustained elevated temperature due to persistent fever to high environmental heat and humidity lead to early embryonic death.

Immunologic Factors

• Also considered to play a role.
• Following conception the cow comes into contact with both sperms and embryonic antigens and if the immunosuppressive mechanisms are not functioning properly, the antibodies produced may reduce the fertility.

Time of AI

• AI at too early estrus or at late estrus.
• When aged sperm or ova are involved in fertilization process, the resultant zygote often dies prematurely.

Diagnosis

• Reproductive history.
• Clinical examination.
  • Ultrasound examination.
  • Tubal patency test.
  • White side test.

Treatment

Specific treatments for conditions like delayed ovulation, endometritis may be carried out.

Since most of the cases do not reveal any specific condition the following guidelines may be adopted.

• Bring the animal into positive nutritive balance.
• Do AI twice at each estrus preferably at 12 hours interval or at 24 hours.
• Check the semen quality – use only a high quality semen
• 3 seconds stimulation of the clitoris at AI.
• Administration of 10 mcg of GnRH or 1000 – 1500 IU of LH at the time of AI.
• Administration of 500 mg of depot progesterone on the 4th day of AI.
• Skipping of AI, administration of PGF2 after 9–10 days and fixed time AI twice at 72 and 96 hours.
• Intrauterine infusion of 1 million units of procaine penicillin diluted in saline three times at the onset of estrus, 8 hours after AI and 24 hours later.
• Skipping of AI and intrauterine infusion of 1 to 1.5 million units of procaine penicillin in 20ml of sterile saline daily for 3-4 days.
• Skipping of AI and intrauterine infusion of 2ml of Lugol‘s solution diluted in 8ml of sterile saline.
• Flushing of the uterus with normal saline under a moderate pressure as being done in embryo transfer (to remove cellular debris and also mild block in the uterine tubes).
• Administration of different hormones and antibodies may preferably be tried at separate estrus.

Preventing Repeat Breeder Cows

• Ensure you are serving cows at the correct time. This means that all staff should know the signs of heat. Milk progesterone testing is also useful, cows in a true heat will have very low progesterone.
• Ensure insemination techniques are as good as possible.
• Do not serve cows previously diagnosed as pregnant without doing a cow-side progesterone test to confirm it is has a low progesterone and is not pregnant. If the cow is pregnant AI may cause fetal loss.
• Identify and treat cows with whites before starting to serve them.
• Don‘t start serving too soon after calving. Herds that start early have lower pregnancy rates to service and so more repeat breeder cows.
• Minimize stress at service.

Ovulatory Defects

• Ovulation in the cow is a typical since it occurs 10-12 hours after the end of estrus and 18-26 hours after the ovulatory LH peak.
• Ovulatory defects may be due to endocrine deficiency or imbalance and mechanical factors.

Delayed Ovulation

• Varied incidence of 2 to 18% has been reported.
• Conception rate was reduced in cows that ovulated by the second day after estrus.
• Delayed ovulation is generally assumed to be one of the causes of failure of conception.
• Certain cows have prolonged estrus. However, this is opined to be related to a delay in CL assuming normal steriodogenesis rather than to the delayed ovulation.
• Diagnosis is difficult and requires sequential rectal palpation of the ovaries.

Treatment

• Repeated AI at 24 hours interval two or three times.
• GnRH – encouraging results
• Dose: natural GnRH – 100 µg i/m
• Buserelin – 5 – 10 µg i/m
• Luteinizing hormone (LH)
• Dose – 1000 – 1500 IU i/m or i/v.