Infertility in Cattle
A) Ovarian congenital affections
1- Ovarian aplasia (Agenesis):
- Heifers show the absence of one or both ovaries.
- It may be bilateral or unilateral.
2- Ovarian hypoplasia:
- Incomplete development of the ovary with weakness or deficiency of germ cell due to the failure of migration of primordial germ cells from the yolk sack to the developing gonad during embryonic stage.
- It may be of genetic origin due to a single recessive gene with incomplete penetration.
- It may be associated with an adverse environmental condition.
- In the Swedish Highland breed of cattle, hypoplasia is caused by a single recessive autosomal gene.
- Serum Anti-Mullerian Hormone (AMH) levels in affected females are lower (below 0.5 ng/ml) than normal females.
- The hypoplastic ovary is small (difficult to find), thin narrow structure of firm consistency, and cord- like thickening.
- It may be unilateral or bilateral.
3- Hermaphrodism (Intersex or sex reversed):
- The two sex organs are present in one animal.
- It occurs in all species of animals but most commonly in hornless goats and pigs.
- Types of hermaphrodites:
4- Freemartinism:
- Co–twinning of a heifer to a male brother (Sexually different dizygous twins).
- About 90% of these heifers are sterile.
- It is due to the underdevelopment of the female genital organs during the intra-uterine life.
- The freemartin heifer is characterized by:
- Anestrous
- Steer–like appearance with high limbs and abnormally large ox horn.
- Small narrow pelvis and vulva, prominent clitoris, and coarse vulvar hair and resembles the preputial tuft.
- The udder is ill-developed with small teats.
- Diagnosis:
1- Clinical signs:
- Upwards spurts of urine
- An enlarged clitoris
- A fish-hook vulva confers a different angulation of the external genitalia onto the perineum
2- Karyotyping: Karyotyped by leucocyte culture shows sex-chromosome chimeras. Cytogenetic examination can demonstrate XX and XY chromosome patterns in freemartins.
3- Rectal examination: The ovaries and the uterus usually cannot be palpated and rudimentary. The cervix is absent (diagnostic of the condition).
4- Vaginal examination:
- On vaginal examination, the vagina is short, narrow with a blind vestibule.
- “Fincher pencil test “i.e. when a pencil or test tube is inserted into the vagina, it does not proceed beyond the external urinary meatus. In calves 1–4 weeks old, the normal vaginal length is 13–15 cm, whereas in a freemartin vaginal length is 5–6 cm.
- Vaginal length is easily measured by gently inserting a well-lubricated “Freemartin Probe” (7 cm length) with a blunt end into the vagina.
5- Serum anti-mullerian hormone (AMH) levels measurement: AMH in freemartin animals are 10-72 pg/ml.
6- hCG challenge test: no increased in estradiol or progesterone post-test.
