Management of Bulls at Custom Collection Studs

Chapter 11
Management of Bulls at Custom Collection Studs


Gary Warner


Elgin Veterinary Hospital, Elgin, Texas, USA


Veterinary services for the commercial bull stud


The semen collection – or “custom bull stud” – industry has markedly evolved over the last 50 years. Initially, a large majority of product was provided by large cooperatives or studs that maintained a large resident bull herd, catering primarily to the dairy industry and its needs. Most bulls in these studs were either purchased outright by stud management or secured by a long-term lease, and thus breeders/owners very rarely realized the full rewards of their production successes. Beef cattle were processed as an aside, as the beef industry’s use of frozen semen products was not widespread. As technology and breeding synchronization systems have evolved, the demand for semen in the beef industry has skyrocketed and custom bull studs have developed throughout the United States. These custom studs allow bull owners the opportunity to present herd sires with proven genetic merit, the opportunity to process and store these quality genetics, and to retain ownership and possession of the bull. Also, it gives bull owners the option to access the international marketplace by allowing them to transport the frozen semen product anywhere in the world.


To assure health quality of the frozen semen products, any semen produced for export must meet standards set by Certified Semen Services, Inc. (CSS). Recommendations for housing, collection, handling, and health testing are made and supervised by administrators within this organization. Recommendations for health standards for residents at the bull studs are taken from guidelines published by the World Organization for Animal Health (OIE). This group concerns itself with advising importing and exporting countries on protecting themselves from introducing disease into their countries from foreign sources. Many countries will take the guidelines of the OIE and formulate entry requirements for cattle as well as bovine germplasm, both semen and embryos. Guidelines are specific and must be followed as entry is forbidden unless standards are met.


Veterinarian’s role in the bull stud


As previously mentioned, the primary role of a veterinarian in an artificial insemination center (AIC) is to insure 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) at www.naab-css.org. These are standard recommendations for the industry that are accepted by USDA/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 insure 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 2–4 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 or polymerase chain reaction (PCR). Lastly, testing for campylobacteriosis and trichomoniasis is required during the isolation period and at 6-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 11.1 outlines a basic AI center testing protocol. Please refer to www.naab-css.org for complete details and the most recent updates regarding testing requirements.


Table 11.1 Basic AI center testing protocol per CSS testing requirements.


Source: adapted from Certified Semen Services, Inc. For additional information on CSS, see www.naab-css.org/about_css/














































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 5 serotypes important in USAa Blood test for 5 serotypes important in USAa. At least 30 days after pre-entry test Blood test for 5 serotypes important in 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

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


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


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 11.1

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Aug 24, 2017 | Posted by in GENERAL | Comments Off on Management of Bulls at Custom Collection Studs
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