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12 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 during the time it has been in existence. Initially, a large majority of semen 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 USA. These custom studs allow bull owners the opportunity to present herd sires with proven genetic merit, process and store these quality genetics, and 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.
The Veterinarian's Role in the Bull Stud
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
|
