Bovine Infertility



"Repeat Breeder"



  • A repeat breeder is defined as:
    •  a cow that has calved before, 
    • is less that 10 years old, 
    • has normal heat cycles, 
    • has no palpable abnormalities, 
    • has been bred 3 or more times and is not pregnant.
  • This is a term that is apparently, and for good reason, dying in the theriogenology literature. Researchers have long sought the cause for repeat breeders, but have been stymied. Why? Most likely is the methodology. Researchers gathered cows defined as 'repeat breeders' and then looked for a specific cause. They usually found no single cause that explained all the problems. Not a big surprise when you consider all the possibilities in all the cows. It is difficult to study because in 'repeat breeders', many are cows are probably normal. Few workers have looked at specific organisms to 'create' the syndrome. Also if you look at fertility expectations in normal animals you see that 9% of normal cows would be repeat breeders. We normally assume a problem exists when the incidence is 10-15 %.
Assume 60 % conception rate
1.65 services/conception

Normal Incidence of "repeat breeders", assuming a 60 % conception rate.

Breeding Number Number Bred % Pregnant Number Pregnant
1 100 60 60
2 40 60 24
3 16 60 10
4 6 60 3
5 2 60 1
6 1 60 1
Total 165 60 100

normal incidence to fit definition = 9 %

Ovulation failure is rare to cause infertility.


  • Inbreeding may contribute to repeat breeders.
  • Known genetic causes of infertility : 
    • 1,29 Robertsonian translocation (most common in Simmental, Charolais, also identified in approx. 40 other cattle breeds) , 
    • 14,20 (Simmental)
    •  DUMPS (Deficiency of Uridine MonoPhosphate Synthetase) Holstein) which is an autosomal recessive gene that results in fetal death in first 2 months gestation.
  • A reported XXX karyotype is associated with infertility in Holsteins.
  • ET embryos have very few chromosome abnormalities.
  • About 8.7% chromosome abnormalities have been found in aborted fetuses and abnormal live births.
  • In humans a high percent of miscarriage have chromosomal abnormalities. This is probably because aged gametes result from copulations that are not just at ovulation.
  • Aged oocytes (i.e. 2 wave ovulations have older oocytes than 3 wave, and 'pushing' ovulation of small follicles)
    • May result in compromised luteal function also.

Molecular Cytogenetics Laboratory
Room 318 B
Bldg 1197
Department of Veterinary Integrative Biosciences
Texas A&M University
College Station, TX 77843-4458

Telephone: 979-458-0520
Fax: 979-845-9972

Please call in advance. Laboratory led by Dr. Bhanu Chowdhary

Fertilization failure
  • In normal heifers you have 100 % fertilization one day after breeding. This drops to 85 % in cows, and to 60-70 % in repeat breeders. Therefore repeat breeders seem to have more of a fertilization failure. If embryos are fertilized and transferred, you have normal pregnancy rates.

Abnormal embryos
  • In one study more abnormal embryos were seen in repeat breeders, but if the embryo is normal the result is a normal pregnancy rate.



  • A decreased GnRH or luteinization is the basis for GnRH treatment of repeat breeders. It has been shown that administration of GnRH after the 3rd service helps fertility rates. All the other studies are pretty inconclusive.

Release of PGF from inflammatory conditions such as mastitis can cause luteolysis and pregnancy loss
Inability to prevent PGF release (shown experimentally in a repeat breeder in response to oxytocin administration) causes return to estrus.

Environmental effects


- Summer heat stress (high temperature and humidity)

  • In heat stressed animals progesterone, corticosteroids are higher and estrogen is lower that normal. Since cows have a harder time dissipating heat that heifers, high temperatures affect mature cows more than heifers. The smaller nonlactating cows produce less heat and dissipate heat better, therefore their internal temperature is lower.
  • A Florida summer ET study compared AI in cows to cow embryos placed into ET recipient heifers. The net result is that at 45-60 days the pregnancy rate in the cows was 13.5 % compared to 29.2 % in the ET heifers. This shows that it more of a uterine problem than ova problem.
  • Fertilization rates are normal in heat stressed cows, but day 1 to 2 embryos are affected most by the heat. As blood flow to uterus decreases to shunt it to the rest of the body for cooling, the uterine temperature rises, nutrients decrease, and waste products increase. This leads to more abnormal embryos (poorer quality) being collected from heat stressed cows at 7 days post AI.
  • Treatments for heat stress include air conditioning, but cost and practicality are major factors. You may only need to cool the breeding herd (which would include peak lactation cows), and bred cows. Work has shown that you need to air condition 14 days before and 14 days after breeding to be effective in controlling heat stress.
  • Evaporative cooling  works in low humidity areas only.
  • Wet the cows and then blow them off to help cool them. You must soak cows or an insulating blanket of water droplets forms. This works best for low humidity areas.
  • Shade helps, but there needs to be enough shade to prevent the cows from crowding under the shade and becoming hotter.
  • Decrease the fiber intake. The cow's appetite decreases so they need more concentrated energy.
  • Increase the potassium in the diet to compensate for sweat loss.
  • Seasonal calving can avoid breeding in hot weather. It seems unpopular, but many people are forced into it anyway. Milk pricing may be problem as base pricing is adopted. In this, a price is set on 'base' production over certain time (Aug - Nov) and the producer receives a lower price for milk produced in excess of "base". This is basically designed to punish people for producing an overabundance of milk during high production times and not enough during high demand times.

Click to enlarge

Infectious agents



(See "Abortion" also)

  • See - R.H. BonDurant. Theriogenology Volume 68, Issue 3, August 2007, Pages 461-473 Proceedings of the Annual Conference of the Society for Theriogenology, Proceedings of the Annual Conference of the Society for Theriogenology
  • The association is unclear. But much research has implicated seronegative cows as being prone to infertility when exposed to the virus.
  • Infection at breeding may lead to lower fertility.
  • Bovine virus diarrhea (BVD): effects on first trimester pregnancy
  • Bovine virus diarrhea virus can establish itself permanently in the host
    • “Persistently infected” (PI) animal is the reservoir of infection for the herd
      • Result of in utero exposure to a BVD virus at less than 125 days of gestation (before the fetus has developed a competent immune system)
  • Two major biotypes of BVDV (based on in vitro cell cultures)
    •  Non-cytopathic (NCPB)
    • Cytopathic biotypes (CPB)
    • Both can damage conceptus  between Days 0 and 125,
    • NCPB are represented amongst PI animals
      • Born viremic
      • Infected before they are immunocompetent
      • No antibodies to the NCPB strain of virus they are carrying
  • Two biotype categories
    •  BVDV I
      • Ia
      • Ib
    • BVDV II genotypes
      • IIa
      • IIb
      • Less prevalent but associated with high morbidity/high mortality outbreaks
    • Both genotypes can be of either the CPB or NCPB biotypes.
  • PI animals susceptible to mucosal disease (MD)
    • Acute and lethal gastrointestinal and respiratory inflammatory disease
    • “Triggered by ” conversion of non-cytopathic biotype to cytopathic biotype by RNA recombination of NCPB viruses
    • Sends a PI animal into MD
  • Timing of infection
    • Possible to infect the gametes’ environment in either the bull or the cow
    • Ovary
      • Interstitial
      • Luteal
      • Granulosa and thecal
      • Follicular fluid
      • Oocytes (oophoritis)
      • Follicles
        • Endocrine capability of the follicle had reduced estradiol output by the follicle
        • Reduced progesterone production by the resulting CL
      • Oocytes
      • Primordial follicles
      • Primary follicles
      • Secondary follicles
      • Infected embryos are destroyed
      • Uninfected embryos become uninfected fetuses and survive to term without ill effects
    • Several reports exist of bulls with BVDV-positive semen
      • most caeses, the bull is a PI animal infected with NCPB BVD
  • CP or NCP biotypes of virus induced the loss of the conceptus when inoculated into cows at approximately 30 days
  • Animals viremic with NCPB at the time of AI - conception rates that were similar to controls, but significantly reduced embryonic survival to Day 77
    • Within- and between-biotype and genotype strain differences
  • Day 42 to about Day 125
    • Placentomes are well established,
    • Fetal infection is likely to be the result of placentome infection and associated vasculitis following a period of maternal viremia
    • Infection can lead to abortion, developmental defects (defects of the derivates of the embryonic neurotrophectoderm)
      • NCP BVD only - PI calf born viremic and without circulating antibodies to the infecting strain.
  • Diagnosis
    • Directed at detecting antigen.
    • Virus isolation - gold standard
    • PCR
    • Immunofluorescent assays from buffy coats
    • Immunohistochemistry (IHC) of skin taken from an ear notch
      • Advantages of the skin-punch IHC:
        •  Simplicity of sample collection
        • Efficacy in formalin-preserved tissues
      • Employs a monoclonal antibody against BVDV that can detect a diverse array of isolates
    • Antigen capture ELISA of homogenates of ear notch tissue, buffy coats, or serum - good for most.
    • Many assays sensitive enough to identify PI animals, but few have the sensitivity necessary to detect transiently (acutely) infected animals.
    •  Positive results with the screening tests should be confirmed by virus isolation.
    • Serology
      •  Surveillance tool to:
        • Assess vaccine efficacy
        • Client compliance
        • Confirm exposure after observation of clinical signs suggestive of BVD
        • Sentinel animals (seronegative calves after their colostral titers have waned).
        • Document acute infections in non-PI animals
          • ELISA that can detect BVD-specific IgM antibody will provide evidence of recent exposure
        • Pre-colostral seropositive, virus-negative calf born to a dam acutely infected in late pregnancy, is unlikely to be a threat to other animals, but is a sign that the virus is active in the herd.


  • Control
    • Europe- low prevalence of BVD virus infection, a test-and-slaughter program and complete eradication is near
    • North America, where prevalence is much higher, a more complex approach to control is needed
    • “Closed herd”
    • Identification and culling of PI animals
      • Main reservoir for BVDV in a herd is the PI animal
      • Vaccination alone almost certain to cause disappointment
      • Identifying PI animals difficult
        • National prevalence is thought to be 0.5–2.0%
        • Have to check nearly 200 animals to find the one that needs action.
        • Pooling strategies
          •  Individual animal samples can be pooled
          •  Examined with one of the diagnostic assays discussed
          •  Antigen capture of extracted ear notch samples, buffy coats or sera, or PCR of buffy coats lend themselves to pooling
          • Skin punch IHC assay does not lend to pooling
          • IHC method will yield the necessary information on single test.
          • Assays that detect whole virus or viral nucleic acid must be run twice to distinguish PI from transiently infected
    • Using serology in sentinel animals for surveillance to eliminate the need for vaccination
    • Immunization in North America
      • Because the virus is maintained in a herd via PI animals, it is unlikely that vaccination alone will achieve the protective state desired
      • In combination with identification and removal of PI animals, vaccination can limit the effects
    • Vaccines
      • 180 licensed BVD immunizing products
      • Modified live
      • Killed vaccines
      • Vaccines containing various combinations of Type I and II genotypes
      • Vaccines containing only CP biotypes
      • Only NCP biotypes
      • Combinations of CP and NCP
      • Genotype I antigens protect against type I and to a slightly lesser extent, against type II
      • Type II virus only does not protect against type I
      • Ability of the vaccine to protect the host
      • Ability to protect the conceptus throughout gestation
      • Fetal protection “intercepts” BVDV before viremia and /or population of the placentomes
      • Cell-mediated immunity and humoral immunity both active in preventing the virus from infecting the placentome.
IBR (See "Abortion" also)
  • Infectious pustular vulvovaginitis (IPV) has been shown to cause infertility. Vaccination can cause a transient oophoritis and result in infertility
  • Ureaplasms cause a granular vulvovaginitis by colonization of the vulva and vagina.
  • The conception rate falls to 28 % in the acute phase.
  • It is seen mostly in Canada and the Northern states.
  • The diagnosis is made by clinical signs and culture.
  • Treatment is by using a double sheathed straws and post breeding infusions of oxytetracycline.
Mycoplasmas are similar to ureaplasmas.
  • M. bovis causes infertility, endometritis, and salpingitis.
  • M. bovigenitalium causes an occasional abortion.
  • Acholeplasm has the same signs as same as ureaplasm.
  • These organisms can be cultured from normal animals though.
  • There is no established proof that it causes infertility, but is has been isolated from slaughterhouse cows with pathologic lesions.

Q fever and Bluetongue
  • They may cause repeat breeders and anestrus, but almost all cows seropositive, so it is hard to prove.


  • Agent

    • L. interrogans serovar hardjo. -  was considered the most important of the antigens

    • Leptospira now classified into “genome species” based on  genetic sequences

    • “Lepto hardjo” is actually Leptospira interrogans, serovar hardjo type hardoprajitno, (found primarily in the British Isles).

    • US cattle exposed to a different species Leptospira borgpetersenii, serovar hardjo, type hardjobovis.

      • The two organisms (L. interrogans serovar hardjo and Leptospira borgpetersenii, serovar hardjo, type hardjobovis )share significant surface antigens used for serological typing

      • Different genomically. The L. hardjobovis genome has been markedly reduced, suggesting that it has lost some of the genetic potential to adapt to new hosts

      • For simplicity, L. hardjobovis will be used to denote L. borgpetersenii serovar hardjo type hardjobovis here.

    • L. hardjobovis causes frank abortions, increased infertility (reduced conception rates) associated with carrier cows and and bulls.

  • Diagnosis

    • Most successful diagnostic sample is urine collected shortly after administration of a diuretic

    • Laboratory diagnostic tests include:

      • Fluorescent antibody testing (FAT)

      • Culture

      • PCR

      • Tissue samples using silver staining and immuno-histochemistry.

      • Serology useful , but may require some interpretation.

        •  ELISA

        • Microscopic agglutination testing (MAT)

        • “Acute” and “convalescent” sera may not be beneficial

          • Titers generally peak well before abortion

          • Cross reaction between serovars is common (most labs interpret the serovar with highest titer to be the infecting serovar hardjo antigens)

          • Vaccine titers difficult to differentiate from titers induced by natural infection

            • L. hardjobovis titers above 1:200 can be compatible with a diagnosis of leptospirosis if signs and history are also compatible.

            • Many animals in the same herd may have higher hardjo titers without evidence of conceptus losses

            • Titers produced by cows aborting due to Pomona or other serovars may commonly reach 1.1600 or more

  • Treatment

    • Carrier state exists in the kidney, so need to clear the carrier state
    • Older protocols - combinations of penicillin and streptomycin
      •  Prohibitive milk and meat withdrawal times
      • Availability of dihydrostreptomycin
      • Restriction on the use of aminoglycosides
    • Newer
      • A single injection of oxytetracycline (20 mg/kg, i.m.); not for use in lactating dairy cows.
      • A single injection of Tilmicosin (10 mg/kg, s.c.); not for use in lactating dairy cows.
      • Multiple injections of ceftiofur (i.e., 5 mg/kg, i.m. once daily for 5 days; or 20 mg/kg, i.m. once daily for 3 days); for withdrawal times, see Food Animal Residue Avoidance Databank [FARAD:].
        • east impact on milk or meat withdrawal
        • Dose above the labeled dose so need  milk withdrawal
      • Two injections of amoxicillin (15 mg/kg, i.m. twice at a 48 h interval); 96 h milk withholding time and 25 days meat withholding time.
    • Vaccine
      • Monovalent vaccines provoke cell-mediated Th1-type responses
        • effective defense against abortion or reestablishment of the carrier state, against infection
        • Multivalent vaccines do not induce this type of response.
        • Two monovalent vaccine antigens cross react with serovar grippotyphosa




'Pathologic causes '
White heifer disease (segmental aplasia)

  • These cows may be anestrus or have enough normal uterus that they cycle, but enough of the uterus or oviduct is missing so they do not get pregnant.
  • Salpingitis is difficult to diagnose. 
  • 50% of cows with palpable lesions have patent oviducts 
  • 50% of cows with non patent oviducts have no palpable lesions.
  • Oviduct patency tests such as the PSP and starch grain test are no good for diagnosis.

Metritis and cervicitis can cause a change in the uterine environment that leads to infertility.
Post breeding infusion in these cows is not routinely helpful.

  • Post partum nutrition is most important for fertility
  • If TDN is Low both prepartum and postpartum, fertility suffers.
    pre partum  post partum  conception rate %  
    HI                                         HI 95  
    HI  LO 77  
    LO HI 95  
    LO  LO  20  


  • Vit A had no effect on fertility, but may cause irregular cycles.
  • Vit D deficiency suppresses signs of estrus and delays ovulation.
  • Vit E deficiency may cause reproduction problems.
  • If the BUN is greater than 20 mg/100 ml cows may have low conception rates . The high BUN is from excess dietary protein.

contributed by Bruce E Eilts and modified on 10 October 2007

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contributed by Bruce E Eilts on 25 September 2012


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