动物采精方法.docx

1、动物采精方法Semen CollectionThere are three commonly-used techniques for collecting semen: use of an artificial vagina, digital manipulation, and electroejaculation. The technique used depends on the species being collected and the disposition of the individual male. The Artificial VaginaArtificial vagina

2、s (AVs to the initiated) are used to collect semen from many species, most prominently cattle and horses, but also sheep, goats, rabbits and even cats. Prerequisites to use of an AV are that the male be conscious, not significantly frightened of people, and more interested in ejaculating than in kil

3、ling humans. An AV uses thermal and mechanical stimulation to stimulate ejaculation. As shown in the image to the right, an AV is composed of a tube with an outer rubber lining that will hold water, into which is placed an inner liner that is lubricated just prior to use. The outer liner is filled a

4、nd pressurized somewhat with water at 42-48 degrees Celsius. Shown below are AVs designed for use with bulls (bottom) and rabbits (top). The apparatus in the middle is a type of AV, usually called a director cone, which is used to collect semen from dogs. To collect semen, the male is allowed to mou

5、nt and the penis is diverted into the AV where he ejaculates. It is best to allow the male to thrust into the AV rather than trying to slide the AV onto the males penis. What the male mounts depends on his species and temperment. Females can be used, but unless they are in estrus, they rarely enjoy

6、participating in the process, which can easily lead to injury of any and all of those involved. Another problem with using a female as a teaser is that if you miss with the AV, the female could be bred or possibly transmit venereal disease to the male. For collecting semen from bulls, a trained stee

7、r is usually used. In the case of stallions, a phantom (dummy) is a popular choice for a mount. Digital ManipulationMany males can be induced to ejaculate by applying pressure and massage to the penis. After the male becomes aroused, a director cone of some type, attached to a collection tube, is sl

8、ipped over the penis to facilitate harvesting the semen. This technique is commonly used for collecting semen from pigs and dogs. An initial training period can be helpful, and having a female in estrus to arouse the male often is useful, particularly when the male is shy.Another type of message use

9、d occasionally with bulls is to stroke the ampullae (terminal vas deferens), seminal vesicles and prostate gland through the wall of the rectum; in almost all cases, the bull must be restrained standing in a chute and sedated to allow relaxation and extrusion of the penis. In conjunction with a uret

10、hral catether, one can obtain a sterile ejaculate using this technique. Semen is collected routinely from chickens and turkeys using a form of digital manipulation. ElectroejaculationElectroejaculation involves applying a series of short, low-voltage pulses of current to the pelvic nerves which are

11、involved in the ejaculatory response. It sounds like an extremely unpleasant experience, but doesnt seem to cause much distress in bulls (although they do need to be securely restrained), and is conducted under anesthesia in many species. Electroejaculation can be used with almost any mammal. With f

12、ew exceptions, electroejaculation is the only technique useful for collecting semen from wild animals, in which case the male is anesthetized prior to the procedure. Another advantage of electroejaculation is that it does not require a mount animal, and can be applied in the field using a battery-po

13、wered unit. Finally, electroejaculation can be used to obtain semen from animals that are physically incabable of mounting due to musculoskeletal disease or injury. It is used for collecting semen from quadrapelegic or parapelegic men who desire a child but cannot ejaculate due to spinal cord injury

14、. With bulls, where there is abundant experience collecting semen by both artificial vagina and electroejaculation, the samples collected using an electroejaculator usually have a larger volume (due to excessive accessory gland secretion) and a lower number of sperm. Three pieces of equipment are re

15、quired for electroejaculation. The electroejaculator itself is a power supply with rheostats to control the amplitude of the delivered current and lots of circuitry to prevent accidental electrocution. Second, one needs a collection tube, usually attached to a latex rubber cone (loving cup) in which

16、 to collect the semen. Finally, the pulses of current are applied through an electroejaculator probe. The probe is inserted into the rectum such that the electrodes lie within the pelvic cavity. Older probes had circular electrodes, which often caused undesirable muscle contractions; probes with par

17、allel electrodes on one side minimize this problem. Three probes are shown below - the upper one is a commercial product for bulls and the lower probes were hand-made for use with small leopards (middle) and ferrets (bottom). Successful electroejaculation of an animal demands skill. It is not simply

18、 a matter of punching buttons and turning knobs, but requires finesse in determining the proper timing and amplitude of pulses to apply to a given male. Semen Collection from BullsA large majority of dairy cows in the US, Canada and European countries are artificially inseminated. Artificial insemin

19、ation of beef cows is also popular, particularly in purebred herds. The advantage of AI over natural service is that it facilitates rapid genetic improvement by allowing use of only the top bulls. Some bulls have sired more than 100,000 offspring via AI. Semen is most commonly collected from bulls i

20、n bull studs using an artificial vagina, as described below. Electroejaculation is an alternative method used with bulls that cannot mount or are too fractious for easy handling (e.g. range bulls). Finally, semen can be collected by message of the seminal vesicles and ampullae per rectum. Semen Coll

21、ection via Artificial VaginaSemen collection from bulls using an AV requires three people: one to handle the teaser animal, one to control the bull and one to collect the semen. It is important that the collection area have non-slip flooring to avoid injuries and because ejaculation may be inhibited

22、 if the bull is nervous about his footing. Bulls are heavy and should have regular hoof care. Poor hoof condition can inhibit the bull from mounting or cause pain when dismounting. A steer is most commonly used as a teaser and mount animal. Female teasers are not recommended because of the potential

23、 risk of intromission and spreading of venereal disease. The teaser should be a calm animal of the appropriate size for the bull being collected. The back and rear quarters of the teaser are washed with a disinfectant every collection day. It is also common for the rear quarters to be clipped routin

24、ely. The bulls preputial hair should be clipped in preparation for using the AV. These sanitary precautions are intended to minimize microbial contamination of the semen being collected. For collection, the teaser is positioned straight in front of the bull for mounting. Oftentimes, it helps to arou

25、se the bull if the steer is led around the collection arena with the bull behind, then stopped abruptly, similar to the behavior of a cow in estrus.The artificial vaginal (pictured at right) uses thermal and mechanical stimulation to stimulate ejaculation. The liner of the AV is filled with water at

26、 42-48 degrees Celsius, and the inner surface is lubricated with something like K-Y jelly. An insulating cone is placed over the end from which the collection tube protrudes to avoid subjecting the semen to temperature shock.False mounting is an effective way to sexually stimulate the bull. Providin

27、g two false mounts with two minutes of active restraint and one additional false mount maximizes sperm cell numbers. Final preparations are made to the AV between the second and third false mounts. Proper construction of the AV is important to avoid damaging the bulls penis and to avoid stressing sp

28、erm cells. Successful semen collection with an AV depends on the bull being comfortable around people, and they need to be trained to use the AV. However, bulls are big and dangerous, and personnel safety should be emphasized constantly. Most bulls in artificial insemination centers have a nose ring

29、 installed as a valuable and humane means of physical control. Bulls undergoing semen collection should be haltered and one should never tie a bull up by their nose ring - if startled, then can rip it out which is not only quite traumatic but yields an animal that may be exceptionally difficult to c

30、ontrol. During collection, the person handling the AV must remain aware of where their feet are relative to the bull. As the animal ejaculates, it is common for him to jump forward. To avoid foot injury, collectors should wear boots with steel toes. In artificial insemination centers, bulls are typi

31、cally collected 2 or 3 times per week, with 2 or 3 ejaculates per collection day. The following images depict routine semen collection from a bull. False mounting to arouse bullAn erect penis indicates arousalCollector ready with AVCollector diverting penis to the AVSemen EvaluationSemen should be e

32、valuated grossly for abnormal appearance. The presence of small clots or blood can indicate such conditions as seminal vesiculitis. ParameterNormal ValuesEjaculate volume5 ml (range 1-15 ml)Sperm concentration1200 million/ml (range 300-2500 million/ml)Total sperm per ejaculateTypically 4-5 billionProgressive motilityGreater than 30%MorphologyGreater than 70% normalSemen Collection from DogsSemen is collected from dogs for breeding soundness exams, as well as for artificial insemination. Semen collected