Journal of
`Dairy & Veterinary Sciences
`ISSN: 2573-2196
`Review Article
`Volume 5 Issue 2 - March 2018
`
`Copyright © All rights are reserved by Kubkomawa HI
`DOI: 10.19080/JDVS.2018.05.555660
`The Use of Artificial Insemination (AI) Technology
`in Improving Milk, Beef and Reproductive
`Efficiency in Tropical Africa: A Review
`
`Dairy and Vet Sci J
`
`Kubkomawa HI*
`Department of Animal Production and Health, Federal Polytechnic, Nigeria
`
`Submission: June 29, 2017; Published: March 23, 2018
`*Corresponding author: Kubkomawa HI, Department of Animal Production and Health, Federal Polytechnic, Pmb 35, Mubi, Adamawa State, Nigeria,
`; Email:
`Tel:
`AbstractThe objectives of the study are to review AI practices as rapid means of improving milk, beef production and reproductive efficiency in
`tropical Africa. It is also to showcase the place of AI in livestock industry with the aim of encouraging farmers to adopt the technology for
`better livestock production and food sufficiency. AI is one of the assisted reproduction technologies (ARTs) used in many domestic species
`including bees and human beings. The use of AI is on the increase in horses, beef cattle, sheep, goats, deer, buffalo and dogs. AI has, also, been
`successful in conservation breeding of endangered species such as primates, elephants and wild felids. AI allows for widespread use of genetically
`superior sires that would normally not be available to breeders because they are too expensive to purchase. AI allows for faster and increased
`genetic improvement in cattle allowing for improved herd performance and productivity. It is the most commonly used assisted reproduction
`technologies (ART) in livestock, revolutionizing the animal breeding industry during the 20th century. In contrast to medical use, where intra-
`uterine insemination (IUI) is used only occasionally in human fertility treatment, AI is by far the most common method of breeding in intensively
`kept domestic livestock, such as dairy cattle (approximately 80% in Europe and North America), pigs (more than 90% in Europe and North
`America) and turkeys (almost 100% in intensive production). The other assisted reproduction technologies (ARTs) in animals are generally
`confined to specialist applications or for research purposes, since the cost would be prohibitive for normal livestock breeding. It is recommended
`that, Government and well to do stake-holders in the industry should encourage farmers by supplying semen, reliable methods of estrus detection
`and training AI personnel to achieve higher conception rates.
`Keywords: Powerful tool; Milk; Beef production; Reproductive efficiency; Africa
`Abbreviations: HF: Holstein Friesian; NAPRI: National Animal Production Research Institute; AI: Artificial insemination; ART: Assisted
`reproduction technologies; ET: Embryo transfer; IVF: In-vitro fertilization; ICSI: Intra-cytoplasmic sperm injection; GIFT: Gamete intra-fallopian
`transfer
` interval and age at first calving. Subsequently, livestock owners
`Reports have shown that, the rapid means of improving
`and breeders begin to show high interest in the use of exotic
`milk, beef production and reproductive efficiency is to combine
`breeds or their frozen semen to upgrade the local indigenous
`the adaptability and hardiness of the Bos indicus with the
`dairy cows. The objectives of the study are to review AI practices
`genetically high reproductive and milk yield potentials of the Bos
`as a rapid means of improving milk, beef production and
`taurus through cross-breeding .To utilize the genetic advantage
`reproductive efficiency in tropical Africa. It is also to showcase
`of the cross-breeding, many decades ago, Nigeria imported
`the place of AI in livestock industry with the aim of encouraging
`several Holstein Friesian (HF) sires for cross-breeding with the
`farmers to adopt the technology for better livestock production
`local breeds, especially Bunaji (White Fulani) cows. This effort
`and food sufficiency.
`resulted in a considerable improvement in milk production .The
`results of studies conducted at the National Animal Production
`Research Institute (NAPRI), Shika, Nigeria, on the performance
`According to DeForest [1] and Blacksburg [2] artificial
`of Friesian-Bunaji crossbreds indicated an improvement of
`insemination (AI) is the manual placement of semen in the
`about 60% in milk yield of the first cross, and further increase in
`reproductive tract of the female animal by a method other than
`the level of Friesian blood resulted in an additional gain in yield,
`natural mating. AI is one of the technologies usually referred to
`but with decreasing magnitude and marked reduction in calving
`
`Introduction
`
`Artificial insemination (AI)
`
`Dairy and Vet Sci J 5(2): JDVS.MS.ID.555660 (2018)
`
`001
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`Semen collection
`
`as assisted reproduction technologies (ART), in which, offspring
`are produced by enabling the meeting of gametes (spermatozoa
`and oocytes). Other techniques encompassed by ART include
`the following: in-vitro fertilization (IVF) where fertilization
`takes place outside the body; intra-cytoplasmic sperm injection
`(ICSI) which is a single spermatozoon caught and injected into
`an oocyte; embryo transfer (ET) where embryos that have been
`derived either in-vivo or in-vitro are transferred to a recipient
`female to establish a pregnancy; gamete intra-fallopian transfer
`(GIFT) where spermatozoa are injected into the oviduct to be
`close to the site of fertilization in-vivo; and cryo-preservation
`where spermatozoa or embryos, or occasionally oocytes are
`cryo-preserved in liquid nitrogen for use at a later stage.
`According to Nafarnda [3] in most domestic animals, semen
`is collected by means of an artificial vagina, for example, from a
`bull, ram or stallion, after allowing the male to mount either an
`estrous female or a phantom. The artificial vagina comprises of
`a lubricated liner which is inserted into an outer jacket, between
`the two spaces filled with warm water. The pressure inside the
`artificial vagina is increased by addition of air. The ejaculate is
`collected and deposited into an insulated vessel attached to the
`end of the liner. But boar and dog semen are usually collected by
`manual stimulation. In some species such as dogs and marmoset
`monkeys that are adapted and can be easily handled, it is possible
`to collect semen by palpation or through vaginal washing after
`natural mating. However, in this situation, the spermatozoa
`have been exposed which may be dangerous to sperm survival.
`Human males can usually supply a sample by masturbation,
`except in the case of spinal injury when electro-ejaculation may
`be necessary. Some other primates can also be trained to supply
`semen samples on request in the same manner like human
`beings. In non-domestic species, electro-ejaculation is the only
`possible means of obtaining semen samples. The problem with
`electro-ejaculation is that, the secretions of the accessory glands
`may not be present in the usual proportions, which may have a
`detrimental effect on sperm survival.
`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. The contributions of
`these different glands vary between species and environmental
`conditions. In some species, such as most primates, the semen
`coagulates immediately after ejaculation and then liquefies over
`a period of approximately 30 minutes. In most other species,
`the ejaculate remains liquid, the exception being in camels
`where the seminal plasma is highly viscous and does not liquefy
`readily in vitro. The addition of enzymes has been suggested as
`a means of liquefying primate or camel semen. However, all the
`enzymes tested thus far (collagenase, fibrinolysin, hyaluronidase
`and trypsin) have been seen to cause acrosomal damage in
`spermatozoa and are contraindicated if the spermatozoa are to
`
`Semen constituents
`
`be used for AI. Recent advances have shown that, camel semen
`extended 1:1 volume to volume, will liquefy in 60-90min at 37
`°C [4].Seminal plasma contains an energy source (fructose),
`proteins and various ions such as calcium, magnesium, zinc
`and bicarbonate. Seminal plasma not only activates the
`spermatozoa, which have been maintained in a quiescent state
`in the epididymis, but also functions as a transport medium to
`convey the spermatozoa into the female reproductive tract and
`to stimulate her to allow spermatozoa to swim to the site of
`fertilization. It has been suggested that, seminal plasma, at least
`in horses, is also a modulator of sperm-induced inflammation,
`which is thought to play an important role in sperm elimination
`from the female reproductive tract [5]. Various types of protein
`in the seminal plasma, such as spermadhesins and the so-called
`CRISP (cysteine-rich secretory proteins) are thought to be
`associated with sperm viability. It may that, these protein types
`bind to spermatozoa immediately, setting in motion a series of
`intracellular events through a second-messenger pathway. In
`some species, small membrane-bound vesicles have, also, been
`identified in seminal plasma, seemingly beginning from distinct
`accessory glands in various species. These vesicles, variously
`named prostasomes, vesiculosomes, or epididysomes depending
`on their origin, fuse with the sperm outer membrane, increasing
`motility and possibly being involved in sperm capacitation and
`acquisition of fertilizing ability. However, their exact mechanism
`of action is yet to be elucidated.
`Seminal factors promote sperm survival in the female
`reproductive tract, modulate the female immune response,
`tolerate the concept us, and to condition the uterine environment
`for embryo development and the endometrium for implantation
`[6]. The action in the endometrium is through the activation of
`macrophages and granulocytes, and also dendritic re-modelling
`that
`improves endometrial receptivity to the
`implanting
`embryo. The cytokine release has embryotrophic traits and
`may also influence tissues outside the reproductive tract.
`Contact to semen induces cytokine activation into the uterine
`luminal fluid and epithelial glycocalyx lining the luminal space.
`These cytokines act together with the developing embryo as it
`traverses the oviduct and uterus preceding implantation. Several
`cytokines are thought to be involved, for example, granulocyte-
`macrophage colony stimulating factor (GM-CSF), a principle
`cytokine in the post-mating inflammatory response, which
`targets the pre-implantation embryo to promote blastocyst
`formation, thereby increasing the number of viable blastomeres
`by inhibiting apoptosis and facilitating glucose uptake [7].
`According to Robertson, Mayerhofer, and Seamark [8]. Gutsche,
`Wolff, von Strowitzki, and Thaler [9] interleukin-6 (IL-6) and
`leukocyte inhibitory factor (LIF) are similarly induced after
`exposure to semen.
`Clinical studies in humans showed acute and cumulative
`benefits of exposure to seminal fluid and, also, a partner-
`specific route of action. According to studies by Bellinge et
`
`002
`
`How to cite this article: Kubkomawa HI. The Use of Artificial Insemination (AI) Technology in Improving Milk, Beef and Reproductive Efficiency in Tropical
`Africa: A Review. Dairy and Vet Sci J. 2018; 5(2): 555660. DOI: 10.19080/JDVS.2018.05.555660
`
`Journal of Dairy and Veterinary Sciences
`
`Exhibit 1013
`Select Sires, et al. v. ABS Global
`
`

`

`Processing of semen
`
`Preservation of semen
`
`al. [10] and Tremellen et al. [11] live-birth rates in couples
`undergoing fertility treatments are improved if women engaged
`in intercourse close to embryo transfer. Research has also
`shown that, the use of seminal plasma pessaries by women
`suffering from recurrent spontaneous abortion is reported to
`improve pregnancy success. Partner-specificity of the response
`is suggested by increased rates of pre-eclampsia in pregnancies
`from donor oocytes or semen, when prior exposure to the donor
`sperm or concepts antigens has not occurred [12].
`Although seminal plasma plays an important role in the
`activation of spermatozoa and in the female reproductive tract,
`it is dangerous to long-term sperm survival outside the body.
`Under physiological conditions, sperm cells are activated by
`seminal plasma at ejaculation and then swim away from the
`site of semen deposition in the female reproductive tract. It is
`only during in-vitro storage that, sperm cells become in contact
`with seminal plasma long-term. Thus, it is customary to add a
`semen extender to the semen, to dilute toxic elements in seminal
`plasma, to provide nutrients for the spermatozoa during in-vitro
`storage and to buffer their metabolic by-products. The addition
`of extender, also, permits the semen to be divided into several
`semen doses, each containing a specific number of spermatozoa
`that has been determined to be optimal for good fertility in
`inseminated females [3].
`Semen is used either immediately after collection (fresh) for
`example in turkeys, human beings; after storage at a reduced
`temperature (stored) for example in horses, pigs, dogs; or after
`freezing and thawing (cryo-preservation) for example in bulls
`[1-3].Fresh semen: In contrast to animal species, human semen is
`not extended prior to processing and is not usually kept for more
`than a few hours before use. Poultry semen cannot be extended
`for too long as is done with other species since the sperm cells
`are adversely affected by increased dilution. Goat semen cannot
`be kept at 37 °C because an enzymatic component of the bulbo-
`urethral gland secretion hydrolyses milk triglycerides into free
`fatty acids, which adversely affects the motility and membrane
`integrity of buck spermatozoa [13]. For liquid preservation,
`goat semen can be stored at the temperature of 4 °C, although
`viability is retained for only 12-24 hours. The extension rate used
`for stallion varies among countries as 1:2, 1:3 or even 1:4 (v/v)
`semen extenders. The normal practice in some countries is to
`have 500 million or one billion progressively motile spermatozoa
`for fresh or cooled semen doses respectively. Boar semen doses
`contain three billion progressively motile sperm cells.
`Stored semen: Storing of extended semen at reduced
`temperature helps to extend sperm life by slowing their
`metabolism as well as by inhibiting bacterial growth. Bacteria
`grows by utilizing the nutrients in semen extenders, thus
`competing with spermatozoa for these limited resources, and
`
`release metabolic by-products, thus creating an environment
`that is not conducive to maintaining viable spermatozoa.
`Furthermore, as bacteria die, they may release endo-toxins
`that are toxic to sperm cells. Nevertheless, cooled stored
`semen is the common method used for breeding horses and
`pigs, enabling the semen dose to be transported to different
`locations for insemination. Stallion semen is normally stored at
`the temperature approximately 6 °C while boar semen is stored
`between 16 and 18 °C. Most boar semen doses are sold and served
`as cooled doses. In contrast, some stallions produce sperm cells
`that do not tolerate cooling, rapidly losing progressive motility.
`In such cases, the only option currently is to use fresh semen
`doses for AI immediately after semen collection, although a new
`method of processing, centrifugation through a single layer of
`colloid, has been shown to solve the problem discussed [3].
`Cryo-preservation: Semen is most useful for AI if it can
`be cryo-preserved, since this method of preservation ideally
`enables the semen to be stored for an unlimited period without
`loss of quality until needed for AI. Since the frozen semen does
`not deteriorate in viability, it can be examined until the male
`has been shown to be free from disease at the time of semen
`collection. However, the sperm cells of various species differ in
`their ability to survive cryo-preservation. Ruminant sperm cells
`survive well, whereas poultry sperm cells do not, with less than
`2% retaining their viability on thawing [14]. For farm animal
`breeding, the cost of cryo-preservation and the likelihood of
`a successful outcome following AI must be considered when
`deciding whether to use fresh, cooled or frozen sperm doses.
`The spermatozoa are mixed with a protective solution
`containing lipoproteins, sugars and a cryo-protectant, such
`as glycerol. These constituents assist to preserve membrane
`reliability during the processes of cooling and re-warming.
`However, sperm motility must also be maintained, so that the
`thawed sperm cells can reach the oocytes after insemination and
`fertilize them. In most species, the seminal plasma is removed by
`centrifugation before mixing with the cryo-extender, for example,
`stallion, boar, goat and human semen. The extended semen is
`packed in straws before plunging into liquid nitrogen for long-
`term storage. There is still considerable variation in the success
`of sperm cryo-preservation between different species, despite
`intensive research into the constituents of cryo-extenders and
`the rates of cooling and re-warming. Human spermatozoa can be
`frozen relatively successfully using commercially available cryo-
`extenders and programmable freezing machines. As previously
`mentioned, the ability of cryo-preserved spermatozoa to retain
`their fertilizing ability varies widely between species. New cryo-
`extenders 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 cryo-protectants, in place of glycerol.
`These molecules seem to function better than glycerol for some
`individuals whose sperm cells do not freeze well, for example,
`some stallions. The clarification with this observation is that,
`
`003
`
`How to cite this article: Kubkomawa HI. The Use of Artificial Insemination (AI) Technology in Improving Milk, Beef and Reproductive Efficiency in Tropical
`Africa: A Review. Dairy and Vet Sci J. 2018; 5(2): 555660. DOI: 10.19080/JDVS.2018.05.555660
`
`Journal of Dairy and Veterinary Sciences
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`Exhibit 1013
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`
`

`

`these molecules are smaller than glycerol and, therefore, may
`cause less damage when they penetrate the sperm membrane.
`However, no technique appears to be universally successful
`within one specie. As far as turkey spermatozoa are concerned,
`it seems that, the development of a successful freezing method
`will require more than new cryo-protectants and additives [15].
`Semen evaluation
`When choosing a male for breeding, especially for AI, it is
`imperative to assess its potential fertility by undertaking clinical
`and laboratory examinations. The in-vitro semen evaluation,
`complementary to the clinical examination, is of high diagnostic
`value for assessing testicular and epididymal function, and/or
`the genital tract of the male, allowing elimination of clear-cut
`cases of infertility or potential sub-fertility [16-18]. Likewise,
`the degree of normality of the semen before being processed
`for AI can be analyzed. The semen analysis routinely includes
`an immediate assessment of volume, appearance such as color,
`contamination, sperm concentration and motility, as well as later
`determination of sperm morphology and the presence of foreign
`cells. Once screened for normality, ejaculates preserved for AI
`are assessed for sperm concentration and sperm motility. These
`are the parameters most often used to determine sperm viability
`in post-thaw semen samples as well as to estimate breeding
`potential of a sire under field conditions [16,17,19]. Unfortunately,
`neither a simple semen analysis nor the routine evaluation post-
`thaw enables the determination a priori of the potential fertility
`level that the analyzed semen will reach, particularly after AI.
`The usefulness of these parameters to measure fertility of a
`semen sample accurately is controversial [20] and correlations
`between sperm motility and fertility have revealed large ranges
`of variation [21-24]. Correlations between sperm morphology
`and fertility have, also, been found to vary widely, and have
`most often been statistically non-significant when the semen
`of AI quality grade has been assessed [17]. Researchers have,
`also, used additional laboratory assays to predict accurately the
`fertilizing potential of a semen sample. Individual laboratory
`assays, which evaluate a single parameter, are not effective
`predictors of fertility. However, a combination of several assays
`may provide a better prediction of fertility [25,26]. The testing of
`a large number of parameters should lead to a higher accuracy
`because fertilization is a multi-factorial process [27]. However,
`most of these analyses are expensive and time-consuming and
`cannot be applied under field and/or commercial conditions.
`Sperm analysis conducted under commercial conditions leads
`to the detection of ejaculates of very poor quality associated
`with poor fertility. However, the pre-selection of the samples,
`the high number of sperm per dose and the high quality of the
`semen used in the AI programs reduces the variability, giving a
`low probability of detecting fertility differences associated with
`seminal parameters [28].
`Accurate and precise determination of sperm concentration
`in an ejaculate is important for AI programs in order to produce
`
`Sperm concentration
`
`uniform insemination doses containing an adequate number of
`sperm. A certain safety margin is often used by AI stations to
`ensure that, all insemination doses contain a minimal number
`of sperm. This, also, implies that, some insemination doses
`contain an excessive number of sperm and that males of high
`genetic value are not used efficiently. This safety margin, also,
`affects the average revenue per ejaculate for the AI station. The
`concentration of sperm in a straw is dictated by factors that
`affect semen quality, which are usually based on how the semen
`survives the freezing and thawing process. Factors include
`breed of bull, bull to bull variation, and the time of the year
`the semen is collected. Dairy semen usually freezes better than
`bull’s semen. The average number of sperm cells/straw is 20-40
`million. Proportion of sperm that endure the thawing process is
`between 30 and 80%, which is dependent on the factors listed
`above. The good AI sires will usually not release semen that has
`a post-thaw survival rate less than 30%. Average number of live
`sperm cells/insemination dose is 5-10 million. If the semen is
`gender selected, the straws will contain approximately 2 million
`sperm cells. Additionally, only 30% of the sperm survive the
`freezing and thawing process. Therefore, most companies that
`sell gender-selected sperm recommend that, it only be used on
`virgin estrous cycling yearling heifers [29-31].
`The hemocytometer has often been referred to as the gold
`standard for assessing sperm numbers [29-31]. The equipment
`is slow, however, and multiple measurements of each sample
`are needed to obtain a precise result [31,32]. The use of a
`spectrophotometer is probably the most frequent method used
`by AI stations for assessment of sperm concentration [32,33].
`For satisfactory results, periodic calibration of hemocytometers
`is necessary. The detection spectrum is inadequate for these
`instruments, and accurate quantification of sperm numbers
`in dilute or concentrated samples is challenging [29,34].
`Spectrophotometers over-estimate sperm numbers in dilute
`semen samples and under-estimate sperm numbers
`in
`concentrated sperm samples. For individual raw ejaculates of
`boar semen, differences in the amount of gel particles or debris
`(cytoplasmic droplets, bacteria) can result in an inaccurate
`determination of the sperm concentration [33]. According
`to Evenson who reported that, electronic particle counters
`allow rapid determination of sperm concentration but tend
`to include any debris in the size range of sperm. Fluorometric
`measurements of the amount of DNA using DNA-specific
`fluorochromes have been studied by Fenton and Hansen [34,35]
`but this method requires stoichiometric staining of all DNA and
`minimal unspecific fluorescence from the extender.
`Most frequently, the semen quality of dairy bulls and boars in
`AI centers is evaluated using sperm concentration and motility
`in fresh and post-thaw semen for bulls. While studies by Correa
`et al. [23,36-38] have established a correlation between motility
`and field fertility, and others did not. Good progressive motility
`of spermatozoa is an indicator of both unimpaired metabolism
`
`Sperm motility
`
`004
`
`How to cite this article: Kubkomawa HI. The Use of Artificial Insemination (AI) Technology in Improving Milk, Beef and Reproductive Efficiency in Tropical
`Africa: A Review. Dairy and Vet Sci J. 2018; 5(2): 555660. DOI: 10.19080/JDVS.2018.05.555660
`
`Journal of Dairy and Veterinary Sciences
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`Exhibit 1013
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`and intactness of membranes [39]. Estimation of motility has
`fundamental importance in daily quality control of semen. The
`percentage of motile sperm cells is used to calculate the required
`degree of dilution and to estimate the number of intact sperm
`cells per insemination dose. Regular motility checks of boar
`semen after dilution and during the holding period furnish
`information on the capacity for preservation of the semen of each
`boar and its individual peculiarities. Motility is usually assessed
`visually via a light microscope. It is inexpensive and quick, but
`accuracy depends on the subjective estimation by individuals
`even though, surprisingly, consistent results can be obtained
`[33]. Objective Computer Assisted Sperm Analysis (CASA)
`systems have become commercially available, but these systems
`are not frequently used in commercial AI-centers because of the
`high investment costs [40]. Encouragingly, small sampling errors
`and high correlations with fertility have been reported [41] but
`the reported procedures have to be applied to an independent
`data set to test their repeatability. The main problem in CASA
`systems is related to the standardization and optimization of the
`equipment and procedures [40,42]. A simple visual estimation
`of sperm motility remains a useful tool for routine semen
`assessment for research purposes and in the AI industry.
`As boar spermatozoa show a higher percentage of circular
`movement than those from other species, except stallions, it
`is recommended to estimate the different forms of motility,
`including proportions of progressive spermatozoa
`[39].
`Estimates undertaken using phase contrast microscopy
`within 20-30 min of dilution cannot be integrated easily into
`the production processes. Stored semen should be examined
`regularly and motility values above 60% should be considered
`satisfactory [39].
`Morphological abnormalities of sperm can have a detrimental
`impact upon fertilization and embryonic development [18,43].
`Bulls and boars used for commercial AI are selected to a certain
`degree on the basis of a low incidence of morphologically
`abnormal spermatozoa, so that, statistical calculations concerning
`their correlation with fertility are not very informative [39,42],
`although some evidence for a relationship between sperm
`morphology and fertility in bulls has been presented [44,45].
`A complete morphological examination is recommended when
`bulls and boars are introduced into the AI station and during
`subsequent regular routine examinations [39,45]. Principles
`for determining sample size for morphological assessment of
`spermatozoa were extensively discussed by Kuster, Singer and
`Althouse [46]. The percentage of cytoplasmic droplets in boar
`ejaculates used for AI should not exceed 15%, especially when
`stored semen is used. In addition to the incidence of cytoplasmic
`droplets, the percentage of other morphological alterations
`should not exceed 20% [39].
`A number of classification systems exist for morphological
`abnormalities of sperm, including primary and secondary
`defects, which classify sperm abnormalities on the basis of their
`
`Sperm morphology
`
`The insemination dose
`
`presumptive origin [47] Major and minor defects-a revised
`system where sperm defects are classified in terms of their
`perceived adverse effects upon male fertility [48]; Compensable
`and uncompensable semen traits according to a theoretical
`increase in numbers of functionally competent sperm that will
`or will not solve the problem [18,49,50]. A compensable defect is
`one where the defective spermatozoa either do not reach the site
`of fertilization or fails to initiate the fertilization process. Defects
`that lead to failed fertilization or early pregnancy loss are termed
`uncompensable.
`The number of sperm in the insemination dose is an
`important factor affecting the probability that a female will
`become pregnant after AI, and in litter-bearing animals, also,
`the litter size [51]. To maximize pregnancy rate, the number of
`sperm in a dose is intentionally set high, but this management
`approach tends to obscure differences among males that might
`impact outcome of breeding when fewer sperm are used [33,52-
`56]. Certain males achieve maximum fertility after AI with very
`few motile sperm (1 million for cattle), whereas for other males
`20-30x more motile sperm are required to maximize fertility
`[51,57,58]. At high sperm numbers per AI dose, individual bulls
`differ in their maximal NR%. That is unrelated to the rate at
`which they approach this maximum [49,58]. Vice versa, sub-
`fertile bulls could not be restored to normal fertility by increasing
`numbers of sperm per insemination. Data for cattle are most
`comprehensive, but it would be erroneous to assume that this
`principle, which results from so called “compensable defects” of
`sperm [50], is not operational in other species. Actually, it has
`been stated by several authors that, insemination trials with
`reduced sperm numbers are needed to reveal sub-fertile males
`and/or to detect differences between males [33,33,52,56,59,60].
`From the perspective of validating a diagnostic assay, the
`use of an excessive number of sperm when measuring fertility
`increases the probability that, the compensable defects in sperm
`will be masked [33,54]. A compensable defect is one in which
`low fertility can be overcome, at least in part, by increasing the
`number of sperm in the AI dose [12,58,50]. Low fertility caused
`by an uncompensable defect persists regardless of the number
`of sperm per insemination. Hence, with a compensable defect of
`sperm, the “problem” causing low fertility results from the failure
`of sperm characteristics being expressed before sperm enters
`the oocyte. An uncompensable defect involves an attribute (s)
`being expressed only after a spermatozoon enters an ovum [54].
`When a spermatozoon with an uncompensable defect fertilizes
`an oocyte, it is unable to complete the fertilization process or
`sustain embryonal development, so pregnancy may not be
`detected.
`There
`is an
`increasing
`interest among AI/breeding
`organizations to decrease the number of spermatozoa per straw
`to be used for AI, which may be related to economic revenues
`and the expected increased use of sex-sorted semen in bulls.
`It is generally accepted that, a total of 15 x 106 spermatozoa
`
`005
`
`How to cite this article: Kubkomawa HI. The Use of Artificial Insemination (AI) Technology in Improving Milk, Beef and Reproductive Efficiency in Tropical
`Africa: A Review. Dairy and Vet Sci J. 2018; 5(2): 555660. DOI: 10.19080/JDVS.2018.05.555660
`
`Journal of Dairy and Veterinary Sciences
`
`Exhibit 1013
`Select Sires, et al. v. ABS Global
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`in a frozen 0.25ml straw is enough to achieve an acceptable
`fertilization rate in cattle provided that, post-thaw motility is
`equal to or above 50% [61-63]. Extension of semen to low sperm
`numbers per AI-dose has been related to a decrease in bull sperm
`viability in-vitro with significant bull variation [63,64]. In AI of
`swine, several dose regimens are applied, ranging from 1.5 x 109
`to 6.0 x 109 spermatozoa per intra-cervical insemination dose
`[16,65-67]. A lower sperm dose is more profitable for AI centers
`and makes more effective use of superior boars. However, when
`decreasing the insemination dose, the effect of semen quality
`becomes more important otherwise compensable morphological
`deficiencies can no long