Lecture 8: Bovine Noninfectious Infertility

What noninfectious pathology can cause infertility?

• scarring / adhesions of ovaries

• blockage of oviducts

• uterine lesions / adhesions

• neoplasia: hypothalamus, pituitary, gonads

What are some factors that interfere with fertility?

• genetics

• management

• nutrition

• developmental

• environment

• STRESS

• male vs female

• endocrine

What is the difference between true and apparent anestrus?

• true anestrus: insufficient hormones

• apparent anesturs: failure to detect estrus, failure to know she is pregnant

What are the factors affecting anestrus?

• Nutrition

• Stress

• Ability to detect and treat (if applicable)

• Pathology

• Developmental issues

• Management 

What can cause anestrus?

1. absence of “detected” estrus - no CL or CL present, but not cycling

2. Cycling, but unobserved - silent estrus, poor heat detection

What is the pathophysiology of freemartinism?

• Shared chorioallantoic membranes

• Testicles of male twin develop prior to female →

• Leads to production of AMH →

• AMH affects female tract → inhibits development of duct systems of female

What is AMH?

dimeric glycoprotein in the same superfamily as Inhibin and Activin that travels through bloodstream from male to female

>95% of bovine twins are _____.

fraternal

What is the clinical appearance of freemartinism?

• Much variation

• Most common apparently normal

• Can have small vulva, enlarged clitoris, tuft of hair on ventral vulva

• Internal reproductive organs are abnormal

  • Vestigial ovaries

  • Suppressed development of paramesonephric duct system

  • Possible development of male duct system

  • Most common = small genital tract, hypoplastic ovaries, short vagina, and absent cervix, +/- uterine horns - maybe be small / vestigial

How is freemartinism diagnosed?

• History of twin birth

• Probe vagina

  • Vagina is 1/3 length of normal vagina

  • This test finds 80% of affected animals

• Lab tests

  • Look for presence of Y chromosome in feamale

  • PCR

  • karyotyping

What does fusion of chorioallantois mean in freemartinism?

shared blood supply

What is a freemartin?

an infertile female born as a twin to a male

What are causes of prepubertal anestrus if no CL is present?

• Poor nutrition

• Too young

  • Breed variations: zebu puberty later

  • Dairy earlier

  • Genetic components: larger scrotal circumference = earlier puberty of calves

• Intersex states

  • Freemartinism

  • Ovarian aplasia / hypoplasia

What are the causes of postpartum anestrus if no CL is present?

• Normal 3-5 wks

• Cystic ovarian degeneration

• Metritis (infectious origin)

• High producing dairy cows

• Suckle suppression in beef cows

• Poor nutrition

What are ovarian follicular cysts?

aka cystic ovarian degeneration, ovarian cysts, cystic ovaries

• Thin walled fluid filled follicular structure >25mm

• Can be present on both ovaries

• Absence of luteal tissue

• Persist for a minimum of 10 days

• Interferes with normal ovarian cyclicity and estrus ??

What are the characteristics and signs of ovarian follicular cysts?

• Anestrus → primary sign

• Some show nymphomania (Estradiol)***

• Irregular estrus intervals

• May have “ Bull like ” appearance

• Incidence affects ~ 10% annually

• Increases calving interval by ~ 50 days

• Self recovery in early cyst ~ 50%

• Increased incidence in high producing dairy cattle - lack of Estradiol precursor / metabolic disorders associated with negative energy balance

What type of cells produce androstenedione (precursor to estradiol) and are responsive to LH?

thecal cells

What type of cells, pre-selection, are responsive to FSH alone and produce some estradiol + inhibin?

granulosa cells

What type of cells, post-selection, are responsive to FSH and LH and produce substantial estradiol - aromatization of testosterone?

granulosa cells

How are cells of an ovarian cyst non-functional?

• no estrogen

• no estrus

• no + feedback (Hypo + AP),

• no LH surge

• no ovulation

What is the treatment for ovarian follicular cysts?

What are the causes of post-service anestrus if no CL present?

animal cycled initially, was bred, then never cycled again….usually poor nutrition

What is the biggest environmental stressor that can cause absence of detectable estrus if no CL present?

heat

What type of neoplasia causes absence of detectable estrus if no CL is present?

granulosa cell tumor (uncommon in bovine)

What are the causes of absence of estrus if CL is present?

What is white heifer disease?

incomplete development of paramesonephric ducts during embryogenesis (segmental aplasia)

What can cause unobserved cycling if the CL is present?

What can cause infertility in cycling females that are observed, but do not get pregnant (regular interestrus intervals)?

What causes infertility in cycling females that are observed in estrus, get pregnant (early), but fail to produce a calf?

Early Embryonic Death:

• Environmental stress - HEAT

• Aged gametes - poor timing of AI

• Chromosomal anomalies

Induced:

• Traumatic palpation

• PGF2 release / administration

• Stress