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The primary role of a veterinarian in an artificial insemination center (AIC) is to ensure biosecurity and animal welfare for the bovine population housed there. Standards for testing protocols are established and readily available on the website of the National Association of Animal Breeders (NAAB) (www.naab‐css.org). These are standard recommendations for the industry that are accepted by the United States Department of Agriculture (USDA)/Animal and Plant Health Inspection Service (APHIS) but certainly may be augmented by any further testing considered appropriate by the center's veterinarian.

The ultimate responsibility of the veterinarian is to assure the welfare of the animals under his or her care. Since the stud is usually compensated by the units of semen provided, it is in the stud's best interest to ensure that the cattle in its charge are adequately cared for. This means that feed, water, forage, and facilities meet the best of standards for quality. Although some facilities may retain the services of a nutritionist, others may rely on their veterinarian for suggestions on ration formulation or forage sampling and testing. Supplementation of minerals should not be forgotten for long‐term resident herd members. Quality control of commercial feed rations should be observed and the resident veterinarian should periodically check feed and storage facilities to ensure proper care and quality.

Since the focus of this chapter is the private veterinarian consulting for the bull stud, we should concentrate on the start of the process: entry into the bull stud. There are three periods at which health testing requirements must be performed: pre‐isolation, isolation, and routine testing that will take place at regular intervals after entry into the resident herd.

The first round of testing, pre‐isolation testing, may be done at the farm of origin by the resident veterinarian. Pre‐entry requirements should be met within 30 days prior to entering the isolation facility. If bull owners do not wish to trouble themselves with testing, many custom studs offer pre‐isolation facilities to house the bull while testing is conducted. These pre‐entry requirements also apply to any mount or jump animals to be used in isolation or the resident herd. The isolation and resident testing requirements will be conducted upon arrival at the collection facility and at prescribed intervals thereafter. All testing phases require a complete physical examination, a negative intradermal test for tuberculosis, a negative test for bovine brucellosis, and a negative test for bovine leptospirosis. Those with titers of 1 : 100 or greater for leptospirosis may be reevaluated in two to four weeks. Those with titer no greater than 1 : 400 will be considered stabilized and allowed entry into isolation. Testing for bovine viral diarrhea virus (BVDV) should be performed before entry and a negative result obtained; the testing must only be conducted by virus isolation from whole blood or serum performed in cell culture, followed by evaluation of cell cultures with immunoperoxidase (IP), fluorescent antibody (FA), enzyme‐linked immunosorbent assay (ELISA), or polymerase chain reaction (PCR). Lastly, testing for campylobacteriosis and trichomoniasis is required during the isolation period and at six‐month intervals thereafter. For both diseases, bulls are required to undergo a series of weekly tests, with the required number varying depending on the age of the bull. Table 12.1 outlines a basic AIC testing protocol. Please refer to http://www.naab‐css.org for complete details and the most recent updates regarding testing requirements.

Table 12.1 Basic AIC testing protocol per CSS testing requirements.

Source: From CSS Minimum Requirements for Disease Control of Semens Produced for AI, January, © 2014, National Association of Animal Breeders.

	Testing environment
	Pre‐entry to isolation	Isolation	Resident herd
Physical examination	Conducted by accredited veterinarian	Conducted by accredited veterinarian	Conducted by accredited veterinarian
Tuberculosis	Negative intradermal tuberculin test (within 60 days prior to entry)	Negative intradermal tuberculin test at least 60 days after pre‐entry test	Negative intradermal tuberculin test at 6‐month intervals
Brucellosis	Official test of state where bull is located. Blood serum test (CF, BAPA, or Card)	CF and one BAPA or Card test at least 30 days after pre‐entry testing	CF and one BAPA or Card test at 6‐month intervals
BVDV	One negative virus isolation test performed on either whole blood (animals less than 6 months of age) or serum	Virus isolation and serologic testing at least 10 days after entry into the isolation facility. If seropositive, virus isolation of semen required	Not required
Leptospirosis	Blood test for five serotypes important in the USAa	Blood test for five serotypes important in the USAa at least 30 days after pre‐entry test	Blood test for five serotypes important in the USAa at 6‐month intervals
Campylobacteriosis	Not required	Series of negative culture tests of preputial material or screening by FA, with any positive FA tested by culture for final determination; 1, 3, or 6 consecutive weekly tests; number of necessary tests dependent on age	Negative single culture test of preputial material or FA for screening test at 6‐month intervals
Trichomoniasis	Not required	Series of negative microscopic examinations of cultured preputial material; 1, 3, or 6 consecutive weekly tests; number of necessary tests dependent on age	Negative single microscopic test of cultured preputial material at 6‐month intervals

BAPA, Buffered acidified plate antigen; BVDV, bovine viral diarrhea virus; CF, complement fixation; FA, fluorescent antibody.

^a Leptospira pomona, L. hardjo, L. canicola, L. icterohaemorrhagiae, L. grippotyphosa.

Examination of entry‐level animals should be conducted as soon as possible after admission to pre‐isolation. A good physical should include observation of ambulation on a surface that provides good footing, preferably loose soil or grass. At this time all physical features should be assessed from the muzzle to the tail, paying particular attention to the feet (Figure 12.1). After this initial examination, the bull should be properly restrained in a squeeze chute, head gate, or lock stanchion. For beef bulls, a squeeze chute would be most desirable for restraint. Starting at the head, the oral cavity should be examined, making sure that all teeth are present and showing even wear (particularly important in more aged herd sires). The eyes should be evaluated for clarity, any presence of neoplasia, or previous injury. Make sure both eyes respond to movement and function normally. The ears are checked for any unusual discharge; in some areas of the country they should also be checked for ear ticks. The bull's chest should be auscultated and any abnormalities noted, as should the entire abdominal cavity. Particular attention should be paid to rumenal contractions, both in strength and number. Several peripheral regional lymph nodes are palpated for any evidence of lymphadenitis. Next, the underline of the bull should be evaluated from the bottom of the chute. The preputial orifice is palpated and examined as well as the scrotum, with palpation of the testes and all epididymal structures. Record the scrotal circumference with a scrotal measuring tape. Evaluation of the lower limb joints and hooves is performed at this time as well. Lastly, rectal palpation should be performed to evaluate abdominal structure, with a rectal temperature being taken and recorded. It is vital to pay attention to accessory reproductive organs, with specific interest in the health of the seminal vesicles. During the rectal examination, it is a good idea to massage the crus of the penis to allow an assistant the opportunity to fully extend the penis. Both vaginal rings are palpated and any abnormalities noted. After examination and pre‐entry testing, follow the recommendation of the NAAB/CSS for entry into isolation after presentation at the stud. Some producers may not be interested in submitting a bull for further testing as they have no desire to export semen. It is always recommended to follow CSS guidelines on any mature bull that has been breeding cows before presentation for collection.

Figure 12.1 Bulls going into a chute.

At the time of entry into isolation at the bull stud, or AIC as some like to be called, the bull is assigned a unique sire code number per the NAAB uniform coding system, if the stud is an NAAB participant. This code is separate and apart from any tattoo or brand used in a breed registry. The bull may display this code in a number of ways but most AIC's use ear tags with the code plainly marked. This code can be used by the center to identify product produced by the bull, although other permanent identification is used for health testing purposes (i.e. hide brands or tattoos).

After admission the bull entering the isolation facility must go into a pen that has been properly cleaned of any residual organic material deposited by the former occupant and disinfected (Figure 12.2). For stalls with dirt floors, a disinfectant applied as a mist over the area should be sufficient to meet NAAB standards. The veterinarian should be aware of the facilities and any damaged portions of housing that could injure an animal. The isolation facility must be separate and apart from the resident housing. All equipment used for cleaning, feeding, watering, and semen collection of the isolation bulls must remain separate from the resident herd. This includes feed storage and any mechanical means of transport. Workers must change boots or protective cover before entering or leaving an isolation area and going to other quarantine areas. Testing on the isolation bulls starts with an intradermal test for tuberculosis performed at least 60 days after the pre‐entry test; a test for bovine brucellosis not sooner than 30 days after the pre‐entry test, with negative result; and a test for bovine leptospirosis not sooner than 30 days after the pre‐entry test, with negative result or subject to stabilized titer of less than 1 : 400. Bovine campylobacteriosis requires up to six cultures and examination of preputial wash material collected at weekly intervals. Bovine trichomoniasis has the same weekly culture requirement during the isolation period. Testing for BVDV is performed no longer than 10 days after entry via whole blood or serum, with evaluation by FA, IP, or PCR on cell culture. All bulls having semen collected will have future testing for BVDV before semen is released. Semen testing by PCR is preferred, with at least one passage through cell line culture.

Figure 12.2 Ideal conditions for housing bulls in central Texas, Elgin Breeding Service.

Veterinarians should also familiarize themselves with the diagnostic laboratory they will be working with, particularly with regard to sample submission requirements, the intricacies of testing procedures, and especially testing protocols and the reporting of test results, as understanding results is very important. Any positive test results, particularly on pre‐entry tests, should be evaluated in conjunction with previous vaccination history. Frequently, certain vaccines produce a prolonged immune response that may interfere later on with attempts to approve semen for export. Leptospirosis vaccination produces a persistent titer for prolonged periods in certain cases.

Once the bull meets all the requirements of the isolation protocol, he is allowed to enter the resident herd, where testing is continued to assure compliance with international protocols. The required testing is preformed semi‐annually on each bull occupying the resident herd. Previous testing is continued at a less frequent pace (every six months), with tuberculosis, brucellosis, leptospirosis, trichomoniasis, and campylobacteriosis all evaluated using the same testing protocols as discussed earlier. Bulls must be restricted from any contact with any other cloven hoofed animal; if such contact occurs, the bull must be returned to isolation and the testing protocol for isolated bulls must be followed once again.

Facility overview is another responsibility of the veterinarian. Supervision of the artificial vagina (AV) preparation room, collection area, bull housing, and semen lab and processing area should all be evaluated for cleanliness, absence of any cross‐contamination, and ability to disinfect contact surface areas. Semen processing equipment should be clean and serviceable and packing and shipping areas clean and organized (Figure 12.3). The veterinarian is responsible for all these areas, as noted when signing off on any federal export certificate. Accuracy is the goal of the veterinarian to assure that standards set by the OIE and NAAB/CSS are met to ensure continued access to all markets.

Figure 12.3 Semen canisters for storage of frozen semen and embryos. Note the cleanliness and organization of the facility.