Why artificial insemination is good

Most AI training schools use excised tracts to illustrate reproductive anatomy. Often the tracts are dissected to allow students to view the interior of the uterus. This is a useful exercise; however, dissection can distort the relationship between various regions. Figure 1 is an illustration of the reproductive anatomy of the cow and a radiograph photograph of an X-ray of the cervical region and uterus.

Radiography allows students to view the intact tract and simultaneously observe the interior of the uterine body and horns and, in many cases, the cervical canal. Figure 1. Diagram side, or lateral, view of the reproductive anatomy of the cow and radiograph top, or dorsal, view of the cervix, uterine body, and uterine horns.

The uterine body is the area between the internal cervical os and the internal uterine bifurcation, where the uterine horns begin to separate inside the reproductive tract. Obviously, there is not much room for error in placement of the insemination rod tip. While palpating the reproductive tract to find the landmarks for insemination, the inseminator usually obtains an idea of the overall size of the reproductive tract.

Some inseminators may have the impression that the larger the cervix or the longer the reproductive tract, the larger the uterine body. This assumption is incorrect. Insemination errors can result from such misconceptions about size of the uterine body in relation to the overall size of the reproductive tract. Critically evaluating the accuracy of insemination has been difficult. For many years, the dye method was used to evaluate the proficiency of professional technicians.

Excised reproductive tracts were inseminated with a biological dye in place of semen. In some cases, live cows were inseminated with dye and the tracts were examined immediately after slaughter. The location of the dye within the tract indicated the site of semen deposition.

Table 1 summarizes the results of dye inseminations in live cows and relates the results to the field performance of technicians to day nonreturn ratings. Nonreturn rate is an indirect measure of fertility.

Technicians with a nonreturn rate greater than 78 percent achieved 86 percent of their dye depositions in the uterine body and they had no extrauterine inseminations. Inseminations by technicians with nonreturn rates below 70 percent resulted in only 34 percent of the dye depositions in the uterine body and 31 percent extrauterine inseminations.

It appears that accurate semen deposition is correlated with successful conception rates. The dye method has some limitations. The location of the insemination rod tip cannot be determined, and manipulation of the reproductive tract during slaughter or dissection can distort the distribution of the dye.

Researchers at The Pennsylvania State University have used radiography to evaluate insemination technique accuracy. This method allows the interior of the tract to be viewed without dissection and the location of the insemination rod to be easily seen. Twenty professional technicians and twenty owner-inseminators were evaluated by this technique. Each participant inseminated twenty reproductive tracts. Two radiographs were evaluated for each insemination.

The first was taken after insemination rod placement and the second after semen deposition. Placement of the rod tip was assessed from the first radiograph and distribution of semen from the second. Analysis of radiographs of all inseminations indicated that only 39 percent of the rod tip placements were within the uterine body. Placements in the cervix, right uterine horn, and left uterine horn were 25, 23, and 13 percent, respectively.

Semen distribution, determined from the second radiograph, showed that 40 percent of the semen was located in the uterine body or equally distributed in both uterine horns. The remaining 60 percent was located in the cervix or disproportionately in one uterine horn. Accurate distribution of semen was significantly related to proper placement of the insemination rod. Human spermatozoa for fertility treatment are usually processed to remove the seminal plasma and to select those of better quality.

In most cases, this is achieved either by sperm migration, in which the more motile spermatozoa are separated from the rest of the ejaculate, or by density gradient centrifugation, where the most robust spermatozoa are selected. The benefits of density gradient centrifugation are as follows Morrell, :. Sources of ROS cell debris, leukocytes, epithelial cells and dead or dying spermatozoa are removed;. Density gradient centrifugation is seldom used when processing animal semen because of the limited volume of semen that can be processed at one time and the time taken to prepare the different layers.

This method is similar to density gradient centrifugation DGC , but is better suited for animal semen since it has been scaled-up to process whole ejaculates. For many centuries, animal breeders and researchers have endeavoured to control the sex of the offspring born, for various reasons. Initially male offspring were preferred for meat production, because of the better feed conversion efficiency and lean-to-fat ratio of males, whereas females were preferred for dairy purposes, except that some males of high genetic merit were still required as sires.

Couples may want a child of a specific sex to avoid the expression of sex-linked disorders. Many methods have been proposed for separating X- and Y-chromosome bearing spermatozoa, based on physical properties, e.

However, the only method which has been shown to work reliably is that of selection and separation of spermatozoa whose DNA is stained with a bis-benzimidazole dye, H, using the sorting capacity of a flow cytometer Morrell et al.

This method functions because the X chromosome is larger than the Y, therefore taking up more of the DNA-specific stain and showing a higher fluorescence when the spermatozoa are passed through a laser beam.

In bulls, for example, the difference in DNA content between the X and Y- chromosome is approximately 4. However, the process of sorting sufficient numbers for an insemination dose in the flow cytometer takes too long, since the stained spermatozoa must pass one at a time through a laser beam for detection of their DNA content. Moreover, the pregnancy rate after insemination of sexed bull spermatozoa is lower than with unsexed spermatozoa, making the procedure inefficient and expensive.

Experience has shown that the staining profiles are highly individual, with the result that it is not possible to separate the X- and Y-chromosome bearing spermatozoa efficiently from all males.

Alternative methods of sex selection are also being investigated. A company in Wales, Ovasort, has identified sex-specific proteins on the sperm surface and have raised antibodies to them.

It is intended to use the antibodies to aggregate spermatozoa bearing a specific sex chromosome, thus enabling them to be removed from the general population.

A combination of ARTs would also be relevant for sperm sexing. Thus, the speed of flow sorting can be increased by first removing the dead and dying spermatozoa from the population, for example by density gradient centrifugation or single layer centrifugation.

Sufficient sexed spermatozoa may be obtained from flow sorting for IVF, thus generating embryos or blastocysts for subsequent transfer.

However, methods of speeding up the selection process are needed if flow cytometry is to become useful for species other than the bovine. As previously mentioned, the ability of cryopreserved spermatozoa to retain their fertilizing ability varies widely between species. New cryoextenders and new protocols are being developed constantly in an effort to address this issue. One recent advance has been the introduction of dimethylsulphoxide and the amides formamide and dimethylformamide as cryoprotectants, in place of glycerol.

These molecules seem to function better than glycerol for some individuals whose spermatozoa do not freeze well, for example, some stallions.

One explanation for this observation is that these molecules are smaller than glycerol and therefore may cause less damage when they penetrate the sperm membrane. However, no method appears to be universally successful within one species. As far as turkey spermatozoa are concerned, it seems that the development of a successful freezing method will require more than new cryoprotectants and additives Holt, Viral infectivity can be removed from the semen of patients with viral infections such as HIV and hepatitis, by a sequential method of sperm preparation i.

Spermatozoa from virally infected men prepared by this method have been used in assisted reproduction attempts, apparently without sero-conversion of mothers or children. However, some studies with HIV report that density gradient centrifugation alone will not remove all viral infectivity Politch et al.

Since spermatozoa may function as vectors for viruses Chan et al. SLC together with swim-up was used to reduce viral infectivity from boar semen spiked with porcine circo virus 2 Blomqvist et al. It has been suggested that AI and other forms of ART could be useful for genetic conservation and preservation of rare breeds. Many of these technologies have been successful to some degree in a research setting, but none have produced results sufficient to effect population-wide improvements in genetic management Morrow et al.

Cryopreservation of semen has been the most widely applied ART in this respect, but much of the frozen semen in so-called gene banks has never been tested for fertility. A lack of suitable females or dearth of knowledge about the reproductive biology of the species involved may contribute to this deficit. However, long-term storage of frozen gametes of unknown fertility is not a sustainable policy for the conservation of rare breeds and endangered species.

The development of in vitro methods of testing sperm fertility would contribute considerably to conservation efforts. Since the semen quality in these animals may be poor Gamboa et al. AI revolutionized animal breeding in the 20th century, particularly in combination with sperm cryopreservation. The AI industry has developed dramatically in most domestic species in the last few decades and its use is now widespread in intensive animal production.

The development of other associated technologies, such as sperm selection and sex selection, are predicted to create powerful tools for the future, both for domestic livestock breeding and for the purposes of conservation. It has been suggested that AI in animals is entering a new era where it will be used for the efficient application of current and new sperm technologies Roca, Exciting possibilities are offered by emerging techniques, such as Single Layer Centrifugation, for improving sperm quality in AI doses as well as for increasing sperm survival during cryopreservation.

Licensee IntechOpen. Help us write another book on this subject and reach those readers. Login to your personal dashboard for more detailed statistics on your publications. Edited by Milad Manafi. We are IntechOpen, the world's leading publisher of Open Access books. Built by scientists, for scientists. Our readership spans scientists, professors, researchers, librarians, and students, as well as business professionals. Downloaded: Introduction The chapter will deal with the use of artificial insemination AI in animals and humans, both currently and in the future, with particular emphasis on comparative aspects between species.

What is artificial insemination AI? Advantages and disadvantages of artificial insemination AI in animals was originally developed to control the spread of disease, by avoiding the transport of animals with potential pathogens to other animal units for mating and by avoiding physical contact between individuals.

Some bacterial pathogens are resistant to the antibiotics in semen extenders or can avoid their effects by forming bio-films; There has been a decline in fertility in dairy cattle and horses associated with an increase in AI; The focus on certain individuals may result in loss of genetic variation.

Antibiotics in semen extenders The addition of antibiotics to semen extenders is controlled by government directives, both nationally and internationally, which state the types of antibiotic to be used and also their concentrations. Collection of semen In most domestic animals, semen is collected by means of an artificial vagina, for example, bull, ram, stallion, after allowing the male to mount either an oestrous female or a phantom. The ejaculate is deposited into an insulated collecting vessel attached to one end of the liner.

Boar and dog semen is usually collected by manual stimulation. Constituents of semen Semen consists of spermatozoa contained in a watery fluid known as seminal plasma that represents the combined secretions of the different accessory glands, such as the seminal vesicles, bulbourethral gland and prostate.

Semen processing Although seminal plasma plays such an important role in activating spermatozoa and in the female reproductive tract, it is detrimental to long-term sperm survival outside the body. Fresh semen In contrast to animal species, human semen is not extended prior to processing see previous section and is not usually kept for more than a few hours before use.

Although some farmers use bulls with their cows after a short AI period, others do not due to concerns for the safety of staff and family.

Once identified, these cows are inseminated by a trained farmer or professional AI technician who perform the technique ensuring minimum discomfort for the cow. Dairy Matters. You ask, we answer. Why is Artificial Insemination AI used in dairy? Some pathogens can be transmitted in semen through artificial insemination, but the collection process allows for the screening of disease agents.

Collected semen is also routinely checked for quality, which can help avoid problems associated with male infertility. Artificial insemination has some potential drawbacks, however, that must be considered. First, it can be more laborious. Male animals instinctively detect the females that are in the correct status for conception. With artificial insemination the detection work falls on the responsibility of the farmer.

Poor detection results in decreased rates of fertility. Also, increasing the number of offspring per male has selective advantages only if the best males can be accurately determined. Otherwise this process only decreases the genetic variability in a population. Increasing the number of offspring per male always reduces the gene pool. The benefits of more intense selection must be balanced against the negative effects of decreased variation. The technique of inseminating a cow is a skill requiring adequate knowledge, experience and patience.

Improper AI techniques can negate all other efforts to obtain conception. Semen must be deposited within the tract of the cow at the best location and at the best time to obtain acceptable conception rates. Early methods of AI involved deposition of the semen in the vagina, as would occur in natural mating. Those methods are not satisfactory. Fertility is low and greater numbers of sperm are required. Another method which gained popularity was the "speculum" method.

This method is easily learned, but proper cleaning and sterilizing of the equipment is necessary, making it more impractical to inseminate than with the rectovaginal technique which is the most widely used AI method today. In the recto-vaginal technique a sterile, disposable catheter containing the thawed semen is inserted into the vagina and then guided into the cervix by means of a gloved hand in the rectum.

The inseminating catheter is passed through the spiral folds of the cow's cervix into the uterus. Part of the semen is deposited just inside the uterus and the remainder in the cervix as the catheter is withdrawn. Expulsion of the semen should be accomplished slowly and deliberately to avoid excessive sperm losses in the catheter.

The body of the uterus is short; therefore, care should be taken not to penetrate too deeply which might cause physical injury. In animals previously inseminated, the catheter should not be forced through the cervix since pregnancy is a possibility. Since research data show little variation in conception rates when semen is placed in the cervix, uterine body or uterine horns, some people recommend incomplete penetration of the cervical canal and deposition of semen in the cervix. The recto-vaginal technique is more difficult to learn and practice is essential for acceptable proficiency but the advantages make this method of insemination more desirable than other known methods.

With practice, the skillful technician soon learns to thread the cervix over the catheter with ease. If disposable catheters are used and proper sanitation measures are followed, there is little chance of infection being carried from one cow to another. A frequent question concerning AI is: What time during estrus should cows be bred for greatest chance of conception? Since estrus may last from 10 to 25 hours there is considerable latitude in possible time of insemination.

Much research work has been conducted on this subject. Controlled investigations were conducted by Trim Berger and Davis at Nebraska in These and other studies show that conception rate is lower when cows are bred prior to mid estrus or later than 6 hours after cessation of estrus standing heat in this case.

Maximal conception is obtained when cows are inseminated between mid estrus and the end of standing estrus, with good results up to 6 hours after estrus. Success in insemination timing is dependent upon a good heat detection program. In large herds, this means assigning individual responsibility for heat detection and a continued education program for labor.

A successful heat detection program and subsequent proper timing of insemination will pay dividends in increasing reproductive efficiency. The animal will be in restlessness and nervousness. The animal will be bellow frequency. The animal will reduce the intake of feed. Peculiar movement of limbo sacral region will b observed. The animals which are in heat will lick other animals and smelling other animals. The animals will try to mount other animals The animals will standstill when other animal try to mount..

This period is known as standing heat.