The problems with AI in cattle

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MANEKA SANJAY GANDHI

Artificial insemination (AI) of cattle is widely practiced in countries with intensive cattle production. In 2017, the National Dairy Plan of this government aimed at artificial insemination for 35 per cent of all fertile animals. The number of inseminations are up from 20 million to 69.29 million.

There are two reasons for the government to adopt this practice: to get more female cattle pregnant from the small amount of sperm, and to maintain control over the sanitary and health conditions.

While the first object has partially succeeded (in quantity, not in quality), the second objective has been a health disaster.

The semen is not checked thoroughly for genetic or communicable diseases. In fact, I am told that none of the centres even have the necessary scientific equipment to check the semen and, since there is constant pressure to increase the semen output, all the international norms are taken very casually. Bulls that are kept in AI centres should be checked for diseases before being taken. They should be kept in low stress, pleasant and healthy conditions. The truth is that the bulls are sick, underfed, never exercised, and very rarely checked for disease. One infected bull can spread disease to thousands of cows via his artificially ejaculated semen. This diseased semen can either cause an abortion in the inseminated cow, or it can result in the foetus being infected.

Certain diseases have become endemic in the cattle population in India. For instance, the spread of tuberculosis has been linked to brucellosis in milk cattle which comes through the semen. Studies done all over the world – even in countries where cleanliness is adhered to – have shown the spread of diseases through AI.

The World Animal Health Organisation has listed several diseases as having proven importance in transmission through semen: foot and mouth disease, vesicular stomatitis, Infectious Bovine Rhinotracheitis (IBR), Bovine Virus Diarrhoea (BVD), papillomatosis, leptospirosis, tuberculosis, paratuberculosis, mycoplasma, anaplasmosis, brucellosis, campylobacteriosis, and trichomoniasis.

138 bulls of the Central AI Laboratory, Savar, Dhaka, were screened for the presence of bovine tuberculosis and brucellosis in 2004. 38 of these were positive reactors to the tuberculin test and one bull was positive for brucellosis. Scientists said that the prevalence of tuberculosis was four times higher in bulls that were used to extract semen than normal bulls. Tuberculosis and brucellosis are not only detrimental to dairy production, but also a threat to human health. Tuberculosis is endemic in most livestock farms in South Asian countries.

Scientists say bovine brucellosis is the best known and most controversial infection of the AI bovine reproductive system. The bacterium has an affinity for the uterus and abortion is the usual sign of the disease. However, other symptoms like reduced milk production and reduced weight are often seen. Infected cows seldom abort more than once, but calves born from later pregnancies will be weak and unhealthy. Such cows will probably continue to harbour and discharge infectious organisms, and have reduced conception rates.

In bulls, the most obvious clinical sign of this disease is infections of the scrotum. Bulls in breeding centres have a persistent inflammation of their vesicular glands, which are duct glands that add nutrients and fluid to the seminal fluid as it passes from the body. The fluid becomes putrid and contaminates the semen at AI centres. The inseminated cow will receive the most dangerous bacteria in her uterus: pseudomonas aeruginosa, streptococcus spp, staphylococcus spp, proteus spp, escherichia coli, mycoplasma bovis, M bovigenitalium. The AI centres rarely check for this, as there are no external clinical signs. The bull may stand with his back arched and have pain on defecation, or rectal examination, and show a great deal of hesitation when made to mount. But these are not signs that the doctors pay attention to.

Another dangerous disease that can be spread by AI is leptospirosis, which is a contagious, bacterial disease of animals and humans. Its signs in cattle range from mild, unapparent infections to ones that end in death. High abortion rates have been observed, bloody urine in bulls and blood-tinged milk in lactating cows. Leptospirosis is an important zoonotic disease and can lead to septicaemia, hepatitis, nephritis, abortion, stillbirth, infertility. The germs survive in the semen at freezing and cryoconservation temperatures.

Bovine herpesvirus-1 (BHV-1) is usually undetected in most clinical tests. BHV-1 causes genital, respiratory and neurological diseases in cattle populations worldwide. Infected animals lose their immunity and are more susceptible to secondary bacterial infections. BHV-1 may also cause conjunctivitis, reproductive disorders and neonatal mortality. Vaccination has little effect. The polymerase chain reaction (PCR) can identify BHV-1 contaminated semen within one day, but it is not done in India. Even vaccinations are rare.

Bovine Diarrhoea Virus in the semen may infect the foetus and establish a persistent infection causing enteric diseases, and making the cow vulnerable to other pathogens as she loses her immunity.

Bovine genital campylobacteriosis is a widespread bacterial disease associated with both bovine infertility and abortion. It causes vaginitis, cervicitis, endometritis. This disease, together with trichomoniasis, has the greatest importance in the transmission of disease through semen.

Trichomonosis is a venereal disease of cattle. In the female it is characterised by infertility, early abortion and pyometra. The bull, who is symptomless, carries it on the penis.

Paratuberculosis, which is caused by the Mycobacterium Avium ssp Paratuberculosis (MAP), may cause Crohn’s disease in humans.

Histophilus somnus bacterium causes the disease known as thromboembolic meningoencephalitis. It has been isolated from semen from apparently normal bulls.

Ureaplasma diversum is the microorganism implicated in causing abortion and infertility in cows. Antibiotics used in semen have not been effective, and it is a pathogen which is frequently found in the bull semen in AI.

Clamidia was found in 9.2 per cent of semen samples, 10.7 per cent of preputial washes and 18 per cent of faecal samples in an investigation carried out on 120 bulls in Germany.

Infectious bovine rhinotracheitis (IBR) is a respiratory disease produced by bovine herpesvirus, type 1 (BHV-1). Infected animals become carriers for life. A new type of virus, bovine herpes virus type 5 isolated from semen (BHV-5), is responsible for neurological problems in calves, and is lethal.

I would like to know whether our vets have any knowledge of these diseases, standards of health certification for AI bulls and the integrity and technical competence with which certification is performed. What are the standards of hygiene applied to collecting, processing and storing semen?

Don’t drink milk.