It seems to us essential to include in the hygiene of semen production the health hazards associated with each step of the process, rather than the narrow aspect of just semen collection, important though this is.
The importance of optimum fertility coupled with rigorous health safeguards is borne out by the enormous extent to which AI is used in cattle, often completely replacing natural service; in Europe some 65 million cows calve each year as a result
of AI, and there is a large international trade in semen, about a million doses being exchanged to and from Europe each year. In view of this great importance, the European Commission has recently proposed to member countries a directive concerning
the safeguarding of animal health in the exchange of bull and boar semen within the Community, and its importation from countries outside the EEC (Economic and Social Council, 1984).
It is obvious that safeguarding the health of semen depends on :
— the disease-free status of the breeding stock;
— the conditions of isolation under which the breeding stock is kept;
— the hygienic conditions of semen collection;
— hygienic precautions during the preparation of semen doses.
The need for good hygiene in the act of insemination by the inseminator is also of considerable importance for the recipient cow and the herd as a whole. The farmer is entitled to expect a certain standard regarding the wearing of suitable clothing, disinfection between each herd (facilitated by using plastic overtrousers and overboots), and disposable gloves. Such precautions help to avoid the major contamination which would otherwise occur.
Freedom of the bulls from major generalised and genital diseases is usually guaranteed by negative results to biological, allergic or serological tests. The value of such a guarantee depends on the precision with which the various procedures (inoculation, sample collection, laboratory testing) are carried out, and the criteria used for evaluating the results and their reliability.
Difficulties arise when « aberrant » reactions occur (e.g. to brucellosis and IBR/IPV virus), but more modern, complex and precise tests can overcome such difficulties without putting the genetic stock at risk. The preparation of cultures from semen, under precisely defined conditions, can remove doubts (concerning FMD and IBR/IPV infection) even if it cannot provide absolute proof. (The only proof provided by culture is a positive isolation of a micro-organism.)
The list of diseases for which bulls are usually tested in most European countries comprises tuberculosis, foot and mouth disease, brucellosis, campylobacteriosis, trichomoniasis, leukosis and coital exanthema (IBR/IPV). There seems to be no
trend towards adding other diseases to the list. To justify an addition there would have to be an increased occurrence of clinical cases of a disease, followed by investigation of the frequency of excretion of the pathogen by AI bulls (and not just the frequency of antibody carriers).
The sporadic nature of abortion and/or infertility due to chlamydia, mycoplasmas, leptospires and BVD virus in cows justifies vigilance and surveillance of any clinical case occurring in an AI bull, but no veterinary authority has so far considered it necessary to introduce systematic control measures, not even Czechoslovakia, where chlamydiosis is responsible for chronic disease in bulls (testicular dystrophy and orchitis), and more than 20% of cows which aborted possessed serum antibody (Polak, 1984).
Standardisation of the diagnostic tests best suited to detect these various diseases would avert the present serious ambiguities and would facilitate international comparisons. This would make international trade much easier.
Quarantine measures sufficiently rigorous in duration and in the absence of contact should provide adequate protection, which only ignorance of the laws of contamination on the part of the personnel can invalidate. During quarantine the animals are examined clinically and submitted to the various diagnostic tests before being admitted to an AI centre. A newly-admitted bull is tested at relatively frequent intervals (3, 6 or 12 months according to the disease being tested for).
Female cattle used as teasers should be submitted to the same procedures.
The hygiene of semen collection and the preparation of semen doses governs the extent of contamination with non-pathogenic or occasionally pathogenic microorganisms.
The staff of an AT centre should be instructed in the rules of hygiene and the methods of implementing them.
A combination of measures capable of considerably reducing the number of micro-organisms in semen has been proposed by Ostachko (1983) working at the Kharkov AI Centre (USSR). Others have also proposed similar precautions, and
Parez (1983) has regrouped them as follows :
— AI bulls should never be allowed to serve a cow;
— the preputial sac and orifice of semen producers should be examined regularly, and any bull with balanitis and/or acrobustitis should be withdrawn from semen production;
— semen should not be collected from bulls having a pendulous prepuce or eversion of the preputial mucosa (because both conditions favour contamination of the prepuce);
— before semen collection the abdomen and prepuce (from which the hairs have been cut) are washed with soapy water and then dried;
— irrigate the prepuce with 250 ml of sterile saline solution about 15 min before semen collection. While the microbial flora of the prepuce may be reduced temporarily by using solutions of disinfectants or antibiotics, the original degree of contamination will be resumed after 2 weeks. Repeated use of disinfectant solutions may result in colonisation by a resistant or even pathogenic flora, with the complication of balanoposthitis;
— the litter (bedding) should be changed regularly, using the same standard of hygiene as practised in cowsheds to reduce infections among cows;
— semen collection should take place on grass, or on a non-slip surface capable
of being easily washed and disinfected; avoid sand and sawdust;
— when a teaser cow is used, its hind parts (which come into contact with the bull's penis) should be disinfected after each collection, or better still, cover the hind parts with a sheet of plastic, renewed for each collection;
— collection should be abandoned if the teaser cow defecates before or during the collection;
•— the operator should wear protective clothing which can be cleaned (plastic or rubber) and a disposable glove should be used on the hand which grasps the penis;
— collection is made after only one penetration of the penis into the artificial vagina;
— the artificial vagina should be disinfected before each use;
— preference should be given to sterile, disposable materials rather than rubber;
— immediately after collection, the semen should be protected from contact with the outside air;
— the laboratory for semen preparation should have its own entrance, away
from the main entrance to the AI centre;
— diluent should be prepared from fresh, sterile products and with sterile equipment. The diluent is a biological medium capable of supporting bacterial growth;
— packing materials for doses of semen should be sterile, and packing should take place out of contact with the surrounding air;
— doses should be for a single animal, hermetically sealed.
Antibiotics have been added to diluents since the 1940's, and at that time they were valuable for destroying Campylobacter in semen. This bacterium has now become a rarity, and the freezing of semen is now widespread, yet streptomycin and
benzylpenicillin are still used. The question should be asked whether the duration of contact at temperatures above 5°C (30 min) or at freezing point (3 h) are adequate to permit these antibiotics to act. Is the range of activity of these antibiotics still suitable for the bacteria they are meant to destroy (Chlamydia, Mycoplasma, Listeria, Leptospira, Salmonella and the ubiquitous bacteria) ? Truscott et al. (1983) demonstrated the effectiveness of lincomycin, spectinomycin and minocyclin
(alone or in combination) against Mycoplasma and Ureaplasma, and they established the limits of activity of these antibiotics. There is a need for further research on the choice of available antibiotics. Another potential line of research is the possibility of immunological intervention, using either specific antibodies (and the initial results of our own experiments have been promising) or active fractions of seru (immunoglobulins) for adding to semen diluents.
Nevertheless, « the use of antibiotics in semen should not be allowed to serve as an alternative to declaring a group of bulls free from disease » (Bell, 1984).
