Management Guidelines


The US AI industry recognizes an ethical obligation as well as an economic and genetic need to practice excellent animal husbandry. From a practical standpoint, the role of a genetically superior bull is to produce large quantities of fertile spermatozoa for transmitting superior traits to a breed of animals. To maximize that superior bull's potential, AI centers make significant investments in labor, feed and facilities to provide optimal care for bulls under their supervision. The AI industry recognizes that sound animal husbandry practices may increase the longevity and productivity of these bulls, and that animal welfare and societal values concerning animal handling must always be considered.

Bulls are housed in clean, well-lit, ventilated buildings or outside in facilities that protect them from inclement conditions. Visual and vocal social interaction is permitted by housing design. Bulls are raised and cared for by trained employees, fed nutritionally correct rations with individual health status continually monitored; the environment is constructed to reduce physical, social and environmental stress.

Human safety and animal safety are two prominent concerns underlying AI center management practices, as bulls may be considered one of the most dangerous males of all the domestic species. Management procedures must be designed to protect human life as well as provide for bull welfare.


Bulls generally first come under the care of AIC personnel when they are transported from a farm or ranch of origin to the AIC facilities. Animals should be transported to the AIC in clean and disinfected livestock trailers with adequate animal space, ventilation, and protection from adverse environmental conditions. Any potential for stress or injury should be minimized during all movements of breeding animals. Obviously, individuals involved in bull transport must be knowledgeable of basic bull care, and should monitor the animals periodically during transit for evidence of injury or illness, with Veterinary care provided if necessary. Feed and water must be provided in accordance with good husbandry practices, with the frequency of care based on environmental conditions. Safety for both human and animal must be observed during animal care and feeding, as well as during animal loading and unloading.


The addition of any new animal to a herd, whether bull or mount animal, presents the opportunity for infectious disease to enter the resident population. All procedures necessary to prevent such potential disease introduction into the AIC must be followed.

The "Certified Semen Services (CSS) Minimum Requirements for Disease Control of Semen Produced for AI" provides a minimum industry standard for AIC health management. These requirements include testing and examination of bulls prior to entry, during an isolation period and semi-annually thereafter, with testing continuing throughout their residency at the AIC.

Animals that do not meet the pre-entry and isolation health testing requirements pose a potential threat to the health of the resident herd and shall be denied admittance. Animals that successfully complete the pre-entry and isolation health testing protocols may enter the resident herd, but must undergo semiannual surveillance testing or other testing as specified by CSS. Mount animals must successfully complete the same health testing regimen as bulls.


Sire hygiene and handling refer to the conditions and practices necessary to promote and maintain animal health in an AI center setting.

Each AIC follows their own established procedures to insure sanitation and to avoid transmission of potentially infectious material. Once a bull has been accepted, the primary objective is to maintain its optimal health and safety. Normally, young bulls are physically identified, receive a veterinary examination, and are vaccinated or receive prophylactic treatment for specific diseases after arrival at the isolation facility.

Isolation premises should be washed and disinfected prior to the admittance of each new group of animals. Animals exhibiting any signs of illness upon arrival or during the isolation period must be removed to a separate area.

Internal surfaces of the housing and pens allow for effective cleaning and disinfection.

In the semen laboratory and AV preparation area the counter tops and equipment need to be routinely washed and disinfected. The walls and concrete flooring of the collection area are cleaned and disinfected on a regular schedule. Non-concrete flooring should be routinely misted with an appropriate disinfectant.

Visitors to the AI center premises must wear protective footwear to avoid transmitting potential pathogens to AIC animals.

In any AIC, bulls are moved from one area to another for semen collection, facility cleaning and to maintain bull hygiene. Bulls may be led by handlers in alleyways, or may be moved through passageways created by a series of gates and pens. Dogs may be used for movement of bulls, as a properly trained dog greatly enhances human safety and does not cause harm or stress to the animal being moved. Mechanical devices may also be used to "walk" the bull, either for exercise or movement within a facility.

The use of “hot-shots” or cattle prods should be prohibited except in exceptional or very unusual circumstances. If used, prods should be in the hands of a Veterinarian or a person well trained in animal welfare issues.

Physical restraint of a bull is required for health tests, veterinary examination and proper hoof care, with the intent being safety for both the bull and the personnel working with him. Generally, bulls are restrained in chutes, locking stanchions or haltered and tied to a physical structure.


Bulls are adaptable to a wide range of environmental conditions. Basic criteria for a satisfactory environment include physical comfort, disease control, access to adequate nutrition and water, and safety for both bulls and handlers. A variety of indoor and outdoor housing systems are used by CSS participants to provide for the needs of bulls, with the specific system generally based on geographic location, age and collection status of resident bulls. The housing system selected should be considered acceptable if the basic criteria listed above are satisfactorily met.

Each bull should have adequate space to move, and a dry area in which to comfortably lie down. In "tie stall" facilities bulls may be tethered, but the animal must be able to lie down, stand, have limited movement, and to eat and drink unhindered. Stalls should be regularly cleaned and suitable bedding materials should be used. Cattle can tolerate a wide range of ambient temperatures; however, housing should be designed to protect bulls from extreme heat or cold. Bulls housed outdoors should have access to shelter for protection from sun and severe weather. Enclosed structures should be properly ventilated or air conditioned to help provide a comfortable environment. Ventilation can be provided actively by mechanical systems or passively with windows and vents, depending on the building design.

Internal surfaces of the housing and pens should allow for effective cleaning and disinfection. To avoid injury, internal surfaces and fittings of buildings and pens should not have sharp edges or projections. Any toxic paint and/or preservative should not be used on any surfaces the animals may contact.

It is recommended that provisions be made for the segregation of sick or injured animals.

Essential mechanical equipment of the AIC, such as waterers, ventilator fans, heating and lighting units, fire-extinguishers, alarm systems, etc. should be inspected regularly to ensure proper working condition. All electrical installations should be inaccessible to cattle and properly grounded.

All facilities and their management procedures should provide safety for both bulls and handlers. Facilities should be designed and lighted to permit easy visual observation of the population, with fences designed to effectively and safely contain bulls. Handling procedures should be designed so that the bull remains constantly under human control, and safety for both the bull and the handler must be implicit. Bulls housed in groups should be dehorned to limit the potential for injury to other bulls. Facilities should be adaptable for the comfort of older animals with age related physical conditions by adding heat lamps, extra bedding, or larger stalls.

In general, performance and condition of the bulls should be the primary indicator of the adequacy of the environment.


Bulls should be fed a nutritionally balanced ration based on National Research Council (NRC) guidelines or adjusted per professional consultation. The feed ingredients should be of good quality; specific feed ingredients vary among CSS AI centers depending on the availability and types of regionally grown feedstuffs. Bulls may be fed once or several times daily.

Clean and good quality water must be readily available. In cold climates, water heaters or insulated waterers should be provided to prevent freezing.


For bulls to achieve and maintain optimum growth and semen production, they must be in good health and physical condition. Various preventive medicine programs are conducted to maintain the health of bulls.

Bulls are regularly observed by Veterinarians and other trained and experienced personnel for clinical health problems or lameness. When a clinical abnormality, illness, or lameness is observed, the bull is evaluated and appropriate action taken. Veterinarians, licensed in their respective states, diagnose and treat disease or injury when such problems occur.

A major component of preventive medicine programs at CSS AI centers is the semiannual (or annual for some diseases) surveillance testing for numerous bovine diseases. Regular testing provides increased assurance that seminal transmission of specific bovine disease agents will not occur. Testing procedures and specimen collections are conducted professionally so that accurate test results are obtained.

Preventive medicine by specific vaccination programs may also be practiced in a CSS AIC; however the bovine diseases prevented by vaccination may be selectively chosen. Robust biosecurity can be a reasonable substitute for some vaccination programs.

Inherent in any genetic advancement or preventive medicine program is the accurate identification of all animals. Bulls are identified on their registration certificate by their color markings or ear tattoo which is unique to each animal. After a bull is accepted into a CSS AIC, it is thereafter designated by a unique sire code number per the NAAB Uniform Coding System. The management of an AIC will identify each bull by its NAAB stud code number by applying an ear-tag, tattoo, neck-tag or leg band. Ear-tagging can be accomplished quickly and safely with various commercially available applicator products. Some ear-taggers must be disinfected between animals; others that do not have direct contact with the animal's ear tissue when the tag is applied do not require such disinfection.

To make handling and leading of the bulls safe for barn personnel, nose rings are applied to most bulls. Trained and experienced barn personnel can safely and quickly insert a bull nose ring when the bull is appropriately restrained and the proper tools are used. Sedation or analgesia may be appropriate for some animals and adequate healing time should be provided before the animal is led by the ring.

Hoof care is an important segment of a complete bull health program, so facilities and equipment for hoof examinations and treatment/trimming should be available. Trained AIC personnel should attend to bulls exhibiting lameness and also provide preventive hoof care. Alternatively, the AIC should be able to transport a bull to a facility where hoof care can be provided or call in a professional hoof care specialist.

Dehorning may be regularly conducted in some AIC management programs. Dehorning bulls of horned breeds provides increased safety to bull handlers and also to other bulls in the resident herd. However, there may be some situations when it is not practical or appropriate to dehorn bulls. For example, AICs may prefer bulls to be horned when bulls are tethered in individual stalls, and certain breed standards require horns. Sometimes a bull is too old to practically dehorn, and all these differences must be recognized. When dehorning is conducted at a CSS AIC, procedures should be performed according to accepted veterinary standards, including administration of local anesthesia.

Within the scope of usual AIC management, castration is obviously not a frequently performed procedure. However, there are circumstances when castration is required, such as to utilize an otherwise healthy but inferior bull as a mount animal. While castration is not always required in this situation, it is an acceptable option available to CSS AIC management. Other situations requiring unilateral or bilateral castration include diagnostic and therapeutic techniques performed for the study or treatment of specific genital problems. When castration is conducted, it is performed according to accepted veterinary surgical standards, including sedation or anesthesia.

Occasionally, the AI Center veterinarian may be required to euthanize an animal that has a debilitating injury or condition that is unresponsive to medical treatment and there is little chance for successful recovery. In these situations euthanasia should be performed to eliminate the animal’s pain and suffering. A publication from the American Association of Bovine Practitioners (AABP), entitled "Practical Euthanasia of Cattle" is an excellent reference on indications for euthanasia, decision making, considerations involving euthanasia and methods to be followed. This information is available from AABP at the following link;


Seminal collection from bulls is basically a simple procedure, but CSS regulations dictate that seminal collections be accomplished following established guidelines and policies regarding bull health and cleanliness, while insuring safety for bulls and handlers. In addition to operating under these guidelines and policies, all seminal collections should meet certain quantitative and qualitative standards. To achieve these criteria, specific bull handling methods and procedures are followed. Normally, the collection of semen is accomplished by a work team consisting of a semen collector and bull handler, but a mount handler may be included. These individuals work together to provide and control the appropriate stimulus situation(s) for the bull.

semen collector - Manages the artificial vagina and performs the actual collection of semen. This person is usually the leader of the team and determines both when the bull is properly prepared and when the seminal collection can be safely taken. In addition, the collector must insure that procedures are hygienic and that semen is accurately identified.

bull handler - Handles the bull via a lead rope. This person must be responsible for keeping the bull under control and safely away from other persons and bulls in the collection arena. This person is also responsible for appropriate mount animal restraint unless that animal is managed by a separate handler.

mount handler - Handles the mount animal via a lead rope or halter. This person is responsible for keeping the mount animal under control while the bull is being prepared for collection.

Seminal Collection Procedure

The seminal collection process normally includes sexual stimulation and preparation, followed by the actual collection of the semen.

[Sexual Stimulation]

Sexual stimulation is described as providing a situation which elicits mounting behavior in the bull; the process starts by exposing the bull to a mount animal in the collection environment. The presence of other animals in the environment, as well as the various visual, olfactory, and auditory stimuli sexually arouse the bull. When sexually aroused, the bull will have a penile erection and will try to mount other bulls and/or a mount animal. (A mount animal is another bull or steer whose role is to provide sexual stimulation for the bull, then stand as the bull mounts, to mimic a natural breeding situation). Cows are not excluded as mount animals but their use is not advocated. Depending upon the libido of the particular bull and the frequency of collection, stimulation may require a few minutes or may require a much longer time.

[Sexual Preparation]

Sexual preparation is the intentional prolongation of sexual stimulation. It is achieved through a series of false mounts (allowing the bull to mount, but not ejaculate) followed by restraint; this practice ultimately results in increases in the quantity and quality of sperm ejaculated. The type of preparation varies widely depending upon the libido and physical condition of the bull, so collectors and handlers need to learn what an individual animal requires. For all false mounts, the semen collector should physically deflect the sheath so that the penis does not come in contact with the hind-quarters of the mount animal. This diminishes the chance of contaminating the penis or mount animal and also serves to prevent possible injury. Some physical and health conditions, specifically rear limb and spinal disabilities may require some bulls be limited in the number of false mounts allowed. Seminal collection procedure for such bulls should be under the supervision of a knowledgeable AIC employee or a Veterinarian.

[Collection of Semen]

The collector should work with the bull throughout the stimulation and preparation procedure to determine the optimum time for seminal collection, which is generally immediately after the false mounting regime is completed.

Semen is collected through the use of an artificial vagina (AV), which is designed to effectively simulate natural breeding. Intromission and ejaculation by the bull into the AV closely mimics what occurs in natural mating. Since the final ejaculation cascade results from tactile stimuli to the bull's glans penis, the temperature, turgidity and lubrication of the AV are important to successful sperm harvest. AV water temperatures between 40° and 60°C are common. A sterile and non-spermicidal lubricant applied to the upper one-third of the AV liner will improve the response of the bull and minimize penile abrasions. Normally the AIC will have AVs of different lengths and diameters to accommodate bull physical differences. The AV is designed so that harvested semen drains into a vial which is removed after collection, properly labeled and prepared for processing.

To prevent potential transmission of disease producing agents during the collection process, the hindquarters of mount animals must be effectively and thoroughly disinfected between successively mounting bulls. In addition, AV equipment must be thoroughly cleaned and disinfected or sterilized prior to each use. A separate AV or AV liner must be used for each ejaculate.


Seminal collection from bulls should be performed using the proper facilities and equipment. The safety of both personnel and animals are of utmost importance. Seminal Collection Arena

It is recommended that the collection arena be large enough to accommodate safe semen collection activities with multiple bulls simultaneously. The size of the arena should be such that the individual bulls and mount animals can be led throughout the area without interfering with one another.

It is important that the collection area provide good "footing" for the bull and mount animal to prevent slipping and subsequent injury. Concrete should be avoided unless surfaces are appropriately grooved.

Passage-ways leading from bull housing areas to the collection arena should be equipped with sturdy guard rails to allow bull handlers to separate themselves from the bull. The railing is generally placed near the center of a walkway so that the bull may be led on one side of the rail while the bull handler(s) walk on the other. It is recommended railings are built in seven to fourteen foot lengths with each length separated by a gap or ”man-pass” approximately fourteen inches wide. This safety man-pass provides bull handlers the option of switching to the other side of the railing if necessary. The fourteen inch man-pass allows the bull handler to easily pass through while a large bull cannot. It is recommended that similar safety equipment and precautions are both available and used in the collection arena.


The use of electro-ejaculation as an alternative seminal collection method should be limited to circumstances where the temperament or physical condition of a bull makes collection of semen by AV either unsafe or impossible. This method should be employed only after a diligent effort to harvest spermatozoa via an AV has failed, including a systematic trial of different teaser animals, bull handlers, collection room stimuli, and collection sites. Casual substitution of this method for knowledgeable and diligent collection room management is not allowed.

When a bull displays shyness of collection personnel, the use of a blindfold during collection should be attempted repeatedly over several days before resorting to electro-ejaculation. Complete physical and behavioral evaluation are essential before electro-ejaculation is considered.

Electro-ejaculation of young bulls failing to demonstrate normal libido is not recommended. Electro-ejaculation should also not be used to compensate for congenital reproductive organ abnormalities that make intromission and/or normal ejaculation impossible.

Collection of semen by this method can be accomplished in a humane and safe manner if consideration is given to the equipment employed, the site and method of restraint, and the training of the person using the electro-ejaculator.

The electro-ejaculators used in CSS-approved AICs should be solid-state with low-amperage output, and complete grounding of the electronics. Current output should not exceed one ampere at maximum power. Machines must be regularly maintained, with particular attention to possible short circuits. Rectal probes with ventrally oriented electrodes, hand-held electrodes, or finger-ring electrodes are advocated to minimize extraneous skeletal muscle stimulation.

The restraint chute used for electro-ejaculation should provide reliable lateral immobilization. Ventral support may be provided for bulls with posterior paresis by using wide leather/nylon straps or belts under the thorax and abdomen fastened securely to the chute frame. Chemical tranquilizers may be used prior to electro-ejaculation, but the drug and dosage should be determined by the attending AIC veterinarian and administered under his/her supervision. Positive conditioning such as brushing or even feeding may relax the animal; any abusive treatment of the bull must not be tolerated.

Machine operators must be properly trained, and initially supervised by an experienced machine operator and/or veterinarian. The operator must be completely familiar with the instrument's controls, the chute, and the bull. Controls must always be checked to verify there is no electrical output before the electrodes are inserted into the bull's rectum. Clearing fecal material from the rectum with a sleeved arm and use of a non-irritating lubricant are essential. Care must be taken to dilate the anus and rectum gently, not forcibly, and if a rectal probe is used, it must be inserted slowly so the rectal lining is not injured.

Consideration of the temperament, physical condition, and responses of the bull must be made when collecting semen by this method. One must expect considerable individual variation in responses, so operators must terminate stimulation if the animal becomes fractious, loses its footing, or is in distress. Slow, methodical increases in power at lower amperage levels usually produces ejaculation well below the maximum output of the machine. Stimulation frequency and level may also be minimized for some bulls by a period of pre-collection sexual preparation, either by massage of the pelvic genitalia or by active preparation and interaction with a teaser animal. After electro-ejaculation procedures the probes or electrodes must be thoroughly cleaned and disinfected prior to their next use.

AIC management must always support animal welfare and insure humane treatment in the management of bulls under their care. Livestock handlers in daily contact with bulls are often the most astute judges of a bull’s temperament and physical responses, so their assessment of an individual bull’s responses to electro-ejaculation should be both solicited and heeded.

Seminal collection by ampullar massage is another alternative collection method, but it has proven inconsistent in harvesting acceptable quality semen. It should be employed only by an individual well experienced in the technique.