Impotentia Generandi in Male Animals: Causes, Types, and Infertility

Impotentia generandi is the inability or reduced ability to fertilize the ovum due to pathology of the testes, mesonephric ducts, or accessory sex glands.

Incapacity or reduced capacity to fertilize in males is referred to as Impotentia generandi. Male fertility is defined as the normal functioning of the testes, accessory sex glands, and ducts to deliver sperm of normal quality and quantity.

Fertility and potency are correlated or related and may differ in the same animal.

Infertility or sterility in males is usually characterized by normal sexual desire and the ability to copulate and ejaculate but the female animals bred by these males may suffer from infertility due to failure of fertilization or early embryonic death.

Impotentia generandi may be of two categories:

1. Impotentia generandi associated with apparently normal semen production.
2. Impotentia generandi associated with abnormal semen production.

1. Impotentia Generandi Associated with Apparently Normal Semen Production

Bulls infected with brucellosis, vibriosis, trichomoniasis, IBR-IPV virus, mycoplasma may produce normal semen but service by these bulls causes failure of fertilization, early embryonic death and repeat breeding in females.

Active brucellosis in a herd of cattle is associated with symptoms of infertility. Intrauterine insemination of brucella infected semen usually results in infertility.

Abnormal acrosomes eg. knobbed spermatozoa related to the defective spermatogenesis involving gogli apparatus is the cause of infertility in bulls, boars and dogs.

Some strains used for preparing the spermatozoa for morphological examination do not reveal this defect. But Nigrosin-Eosin, India ink or Giemsa show a refractive unstained or lightly stained area in the anterior pole or acrosome of the head of the spermatozoa.

The defective acrosome causes the sperm cell incapable of penetrating and fertilizing the ovum.

The acrosomal defects in spermiogenesis is due to an autosomal recessive sex linked defect in Friesian bulls.

Cytogenetic studies of sperms indicated that gene or chromosomal defects may occur at the time of meiosis and result in infertility.

Further many infertile bulls had lower DNA content of the spermatozoan nucleus than fertile bulls.

2. Impotentia Generandi Associated with Abnormal Semen Production

In this condition sufficient number of healthy fertile sperm cells are not deposited properly at the time of coitus to cause the fertilization of ovum and the normal development of the embryo.

Impotentia generandi is due to the pathology of the:

• Testis
• Epididymis
• Vas deferens
• Accessory sex glands
• Urethra

The two most common changes occurring in the testes causing disturbed spermatogenesis are:

• Testicular hypoplasia which is congenital or hereditary
• Testicular degeneration which is usually acquired

Testicular pathology due to congenital or hereditary causes includes testicular hypoplasia, certain defects in the seminiferous tubules and sperm cells including cytogenetic and chromosomal defects, cryptorchidism and inguinal hernias.