Drawbacks of artificial insemination of cattle
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% 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 distasteful practice: to get more female cattle pregnant from the small amount of sperm that a single cow would take in if mated naturally with a bull, and to maintain control over the sanitary and health conditions.
While the first object has partially succeeded (in quantity, not in quality: the inseminated cows are weaker and sicker in every generation), the second objective has been a health disaster.
For two reasons:
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, and then regularly.
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.
In 2020 the American Association for the Advancement of Science in New Scientist (https://www.sciencemag.org/news/2020/04/deadly-livestock-disease-may-have-spread-through-infected-bull-semen) reported that Blue Tongue disease, in which cattle get fever, swelling of the lips and gums, difficulty in swallowing and a swollen purple coloured tongue and which has a mortality that can go up to 90%, may have been caused by infected cattle semen.
In 2006, an outbreak of Bluetongue diseases began in the Netherlands. It spread to 16 countries and cost billions of euros before a vaccination effort brought it to an end in 2010. In 2015, the disease re-emerged in France and this outbreak is still ongoing. To work out the source of the infection, scientists at the University of Glasgow analysed the genetic sequences of 150 samples of the virus from both outbreaks. Researchers wrote in PLOS Biology that the genome of the virus is remarkably similar to samples from the previous epidemic, and would have come through using infected cattle semen, kept in a freezer for years.
The World Animal Health Organization has listed several diseases as having proven importance in transmission through semen. 1. Foot and mouth disease. 2. Vesicular Stomatitis. 3. Infectious Bovine Rhinotracheitis (IBR). 4. Bovine Virus Diarrhoea (BVD). 5. Papillomatosis. 6. Leptospirosis. 7. Tuberculosis. 8. Paratuberculosis. 9. Mycoplasma. 10. Anaplasmosis. 11. Brucellosis. 12. Campylobacteriosis. 13. Trichomoniasis.
One hundred and thirty eight bulls, of the Central AI Laboratory, Savar, Dhaka, were screened for the presence of bovine tuberculosis and brucellosis in 2004. Thirty eight of 138 bulls (27.5%) were positive reactors to the tuberculin test and 1 (0.7%) bull was positive for brucellosis. The 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, spread by the bacterium Brucella abortus, 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 epididymitis or infections of the scrotum. According to the premier veterinary MSD Manual, 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 reported incidence of vesiculitis, in the general population of bulls, is 1%–10% but can go upto 49% in bulls housed in groups.
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 (Eaglesome and GarcÌa, 1997).
Bovine herpesvirus-1 (BHV-1) is usually undetected in most clinical tests. BHV-1 causes genital, respiratory and neurological diseases in cattle populations world-wide. Infected animals lose their immunity and are more susceptible to secondary bacterial infections. BHV-1 may also cause conjunctivitis, reproductive disorders and neonatal mortality (Straub; 1990, Takiuchi et al., 2005). 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 (e.g. BHV-1, Pasteurella or Salmonella spp.) as she loses her immunity. BVDV has caused haemorrhagic disease in cattle with a high mortality rate. The virus is transmitted in the semen of bulls during artificial breeding and causes reproductive losses in females.
Bovine genital campylobacteriosis is a widespread bacterial disease associated with both bovine infertility and abortion. It causes vaginitis, cervicitis, endometritis. Bulls should be tested before they enter AI centres, and then every few months. This disease, together with trichomoniasis, has the greatest importance in the transmission of disease through semen (Rovay et al., 2008).
Trichomonosis is a venereal disease of cattle caused by the parasite Tritrichomonas foetus. In the female, it is characterised by infertility, early abortion and pyometra. The bull, who is symptomless, carries it on the penis. The testing of bulls entering AI should be mandatory.
Paratuberculosis, which is caused by the Mycobacterium avium ssp. paratuberculosis (MAP), may cause Crohn’s disease in humans (Sanderson et al.; 1992; Reddacliff et al., 2010). MAP has been isolated from bull semen and reproductive organs (Tunkl and Aleraj, 1965; Larsen and Kopecky, 1970; Larsen et al., 1981). This bacillus is unaffected by the antibiotics most used in semen (gentamycine, tylosin, lincomycine and spectinomycine) (Visser et al., 1999).
Histophilus somnus bacterium causes the disease known as thromboembolic meningoencephalitis. It has been isolated from semen from apparently normal bulls (Humphrey et al., 1982).
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 semen of bulls used for AI. It has been found in more than 50% of the samples obtained from 35 bulls at a collection centre, in a study carried out in Brazil.
Clamidia was found in 9.2% of semen samples, 10.7% of preputial washes and 18% of faecal samples in an investigation carried out on 120 bulls in Germany (Kauffold et al., 2007).
Infectious bovine rhinotracheitis (IBR) is a respiratory disease produced by bovine herpesvirus, type 1 (BHV-1). Infected animals become carriers for life (Van Oirschot, 1995.) 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 (Chowdhury, 1995.)
In an investigation done on 103 farms in Columbia, Griffiths et al. (1984) isolated Trichomona foetus and Campylobacter foetus in 13.7% and 15% of bulls. Another study found 23.9% positivity for Tritrichomona, 17.3% for Campylobacter, 43.4% for Salmonella, 28.2% for Brucella and 52.17% for Leptospira (Villalobos et al., 1986). A 67.6% IBR prevalence has been reported in breeding bulls (ZuÒiga et al., 1978) Another study revealed the presence of IBR/BVD (17%), BVD/ Leptospira spp (83%), BVD/BLV (42%), BLV/ Leptospira spp (31%) and BVD/BLV/Leptospira spp coinfection (33%) (GÛngora et al., 1995). IBR, BVD and Leptospirosis prevalence was 90%, 33% and 5% in 60 bulls (Sanabria and Trujillo, 2002). The following questions arose internationally: Does the semen produced and sold in Colombia comply with the existing standards ? We could ask the same question of India.
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.
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