the cylinder of the collection handle and held in place with a rubber ring on the outside of the cylinder. Commercially available semen vials or a urinalysis tube can be passed, bottom end first, through the collection cones and pulled snuggly through the smaller opening to make a tight seal near the opening of the vial (Figure 9.2). Bovine semen is sensitive to chilling, with the most noticeable effect being a rapid decline in sperm motility. Vials and collection cones should be kept in a warming area and only brought out just prior to use. Spare vials can be kept warm in a chest pocket or on a microscope warming stage. Warming jackets containing water can be fashioned from plastic bottles and attached to the collection handle using adhesive tape. Styrofoam coffee cups can also work well as a collection vial, with their insulating capability being an additional benefit when ambient temperatures are cool.
Figure 9.2 Semen collection handle, cone, and vial.
Numerous anesthetic protocols have been employed to evaluate and potentially reduce potential pain or anxiety associated with EEJ, but none of them can be considered to be viable alternatives to conventional EEJ. Caudal epidural anesthesia with 2% lidocaine appeared to be just as effective as conventional EEJ with lesser elevations in cortisol, but did not significantly affect heart rate change [13, 19]. The benefits did not appear to justify the time and effort expended administering the epidural. Xylazine, administered in an epidural or intravenously was effective for reducing pain, but because of associated ataxia and recumbency its use is not practical [12]. Intrarectal lidocaine reduced intrarectal smooth muscle contractions, but its effect is only superficial as heart rate change remained unchanged compared to conventional EEJ [3]. Although not all studies agree, the majority have shown that EEJ can be mildly painful [12] and stressful to bulls; however, heightened awareness and improvements in probe and electroejaculator technology coupled with careful, conscientious use have substantially decreased these concerns.
A mainstay in bull studs, the AV and a mount animal are very useful for collecting semen from trained animals, but are not practical for use with most beef bulls used for pasture breeding. Phantom cows, similar in design to the phantoms used for stallions, complete with an AV mounted within the frame were tested with untrained beef bulls. Not even the application of estrus cow urine sprinkled on the hides that covered the phantoms would entice the bulls to mount and serve [12]. Serving capacity tests are used to evaluate libido and the ability to mount and complete service [20–22]. These tests are conducted by introducing one or more bulls into a pen containing at least one cow restrained in stocks. Having cows in estrus may increase the sexual interest of some bulls [20]; however, willingness to stand to be mounted is a major cue used by breeding bulls that the female is ready to be mated. Therefore because they are restrained the cows used in these tests do not need to be in estrus. Although serving capacity tests are not considered to be reflective of true breeding behavior in juvenile bulls, most mature bulls will express sexual interest in and mount a restrained cow [20].
Early attempts to modify the serving capacity test to enable the collection of semen involved having a person deflect the bull's penis away from the cow and into an AV. Most untrained bulls were unwilling to mount with a person standing close by, so attempts were made to conceal the operator behind drapes while the bull mounted and semen was collected [12]. High libido bulls were undeterred by this system, but medium to low libido bulls seemed to be distracted by the drapes or the presence of humans behind the drapes and refused to serve. [12]. The next modification was to design an AV that could be fitted inside the cow's vagina, called the internal artificial vagina (IAV). The IAV consisted of a wire frame supporting a 7.5‐cm length of rubber tubing with a plastic specimen bag attached to the end placed closest to the cervix [23]. Once the bull had mounted the cow and completed service the IAV could be quickly removed and the semen sample recovered. Over a two‐year period, the IAV was compared to EEJ as a method of collecting semen from 165 range bulls. Fifty four and seventy percent of the bulls served the IAV in years one and two, respectively versus a 100% success rate when EEJ was used. Five percent of the bulls were found to be unable to serve cows due to physical abnormalities. Bulls that were unwilling to serve the IAV in year 2 were given a second opportunity, but the result remained the same. Over the subsequent breeding season, the breeding behavior of 15 of the bulls that did not serve the IAV was compared with 15 that did. Most of the bulls that would not serve the IAV were observed breeding cows but mounted less frequently than their counterparts [23]. The IAV proved useful for identifying bulls with physical abnormalities but was not a viable substitute for EEJ. Other concerns included the spread of venereal disease and the welfare of the restrained mount animals [12].
Transrectal massage of the seminal vesicles, ampullae, and pelvic urethra has been used as a method of obtaining a semen sample but is not as reliable as EEJ. In one experiment, TM was shown to be nearly as effective as EEJ for obtaining a semen sample [24], but the percentages of motile and live sperm were less than those of EEJ samples. This was attributed to the tendency of massaged bulls to dribble semen slowly, thereby exposing the sperm to cool temperatures for a longer period of time [24]. Two more experiments were conducted comparing TM with EEJ in infrequently handled, mature breeding bulls (range bulls) and yearling bulls. In an attempt to prevent chilling of the sperm, semen collection tubes were suspended in a 37 °C water jacket during the collection. Despite this effort, fewer motile and live sperm were recovered from TM samples in the range bulls, but there was no difference in percentages of motile sperm in the yearling bulls [25]. These differences were attributed to lack of penile protrusion during semen collection with TM – a problem that was particularly evident with the range bulls [25]. The differences in live and motile sperm percentages were not large, but these authors cautioned that poor semen sample quality and an inability to examine the penis could jeopardize the quality of a BBSE [25]. Transrectal massage of the seminal vesicles and ampullae can be useful following an unsuccessful attempt to electroejaculate a bull. In these cases, the maximum voltage has been reached but only preseminal fluid has been emitted. One useful trick is to rest the bull for at least 30 seconds and restart the collection at a much lower setting. If this quick fix fails, then the probe can be removed and TM may be effective.
Aspiration of semen from the vagina of a recently bred female is a last resort method of obtaining a sample as it is time consuming and requires a female in estrus that must be restrained to allow a sample to be obtained. A syringe and infusion pipette will facilitate the collection of mucus and semen from the anterior vagina.
Semen Evaluation
Once the semen sample has been collected the vial can be easily detached from the semen collection cone. To avoid spillage it works best to pull the cone sideways and slightly downward away from the vial, which has the effect of stretching and shearing the cone off on the edges of the vial. Always keep the semen vial protected from the cold prior to evaluation. A simple and effective method is to hold the vial in a warm hand with the fingers completely encircling it. If evaluation is not going to occur right away the sample should be transferred to a 37 °C water bath. The chest pocket of a close‐fitting pair of coveralls has also worked well for short‐term storage, especially if the hands are needed for other tasks.
Although not always recorded, the skilled examiner should know how to assess each of the following when examining a semen sample:
Color and consistency
Volume
Concentration
Gross motility
Individual motility
Sperm morphology
Percentage staining alive
Color and Consistency
A good quality ejaculate should be opaque, creamy‐white in color. A yellow, buttery hue may also be seen and is a variation of normal when it occurs