Introduction of Seman Into the Uterus by Non-natural Means Beef Cattle With Brahman Influence

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Anatomy of the Cow's Reproductive Tract

11 June 2007

By Dr. R.West. Prange and Dr. R.T. Duby University of Massachusetts and published by West Virginia University Extension Service. Successful reproduction on modern dairy farms requires an understanding of reproductive processes of the dairy cow and a working cognition of the anatomy or parts of a cow'southward reproductive tract.

This knowledge tin can be useful in identifying and correcting many situations leading to poor reproductive efficiency.

Except for the vulva, all parts of the reproductive tract are located within the body of the cow. Parts (Fig. 1) encountered as 1 proceeds into the reproductive tract include the entrance hall, vagina, neck, uterus, oviducts and ovaries. The internal parts are located beneath the rectum, which allows rectal palpations of the tract to exist done hands. The uterus, oviducts, and ovaries are attached to a ligament and suspended in the moo-cow's pelvic expanse. This suspension allows these organs to move freely in the pelvic culvert and into the body cavity, providing infinite to accommodate a growing fetal dogie.

The Reproductive Tract

Vulva

The vulva (Fig. 1) is the external part of the reproductive tract. The thickened folds of skin of the construction are sensitive to changes in estrogen, the hormone (Fact Sheet IRM-2) responsible for estrus (oestrus). Swelling and redness of the vulva, due to increased claret flow, can be useful in estrous detection when coupled with other signs.

Vestibule

The vestibule (Fig. ane) is a part of the reproductive tract shared with the urinary system. Information technology is approximately 4 inches long. Openings from the urinary float and a blind sac located below the opening of the urethra chosen the suburethral diverticulum are located on its flooring. Dairy producers and Al technicians tin prevent insertion of an inseminating rod into these openings, which could result in injury or insemination failure, by knowing their location.

Vagina

The vagina is located between the opening to the bladder and the neck. Approximately eight inches long (Fig. 1), it is the site of semen deposition during natural service. The vagina also serves every bit an unrestrictive passageway for the dogie at time of birth. One important part of the vagina is every bit a line of defense against invasion past bacteria. The epithelium of the vagina secretes fluids which combine with cervical fluids to inhibit growth of undesirable bacteria.

Protection from infections may non be sufficient when unsanitary housing atmospheric condition are prevalent, or dirty inseminating equipment is used. Equally a event, vaginal infections can exist a problem. In addition, pooling of urine in the vagina adjacent to the cervix tin cause infertility in some older cows.

Cervix

The cervix (Fig. 2) is a unique structure within the reproductive tract. It is 4 to v inches long and one to 2 inches in diameter and lies between the vagina and uterus. This structure is designed to restrict admission to the uterus. The area effectually the opening of the cervix actually protrudes dorsum into the vagina. This protrusion deflects such things as inseminating rods away from the cervical opening if intendance is not taken during insemination.

Likewise, the walls of the cervix are thick and dense in comparison to the walls of the vagina. Iii or four ridges or rings within the body or the cervix, chosen annular folds, can be distinguished by rectal palpation (Fig. 2). The folds must be manipulated rectally while an inseminating rod is passed through to the uterus.

The cervix has important functions. The anterior neck may serve equally a site for semen deposition during artificial insemination (Al). This occurs on services where the cycle length is non 21 days and pregnancy from a previous service is possible. Whether by deposition following Al or by migration from the vagina after natural service, the cervix acts equally a reservoir for semen. The cervix provides a favorable environment for sperm survival.

Secretions of the neck are usually thick, only these fluids sparse at the time of estrus to facilitate transfer of sperm to the uterus. Some of the mucus may exist seen every bit belch from the vulva effectually the time of oestrus. The cervix, or fluids of the neck, act as a physical barrier and protect the uterus from any foreign textile or bacteria during pregnancy. A thick plug forms in the canal of the cervix and blocks access to the pregnant uterus. Adventitious rupture of this plug by insertion of an inseminating rod can consequence in abortion.

Uterus

The uterus (Fig. 1) consists of a "body" and two "horns". It is attached to the wide ligament and suspended within the pelvic crenel and posterior portion of the trunk cavity. The body of the uterus is adjacent to the cervix. In a not-pregnant country it extends less than ii inches before it divides into 2 carve up horns (Fig. ii).

The uterine torso is the major site of semen deposition during Al. If the tip of the inseminating rod is inserted too far into the uterus, semen is deposited in only one of the uterine horns (Fact Sheet IRM-12). If the egg was released from the ovary on the other side, in that location is footling chance that sperm and egg would unite. Retrieve, the body of the uterus is less than two inches long and caution must be used to correctly deposit semen into this region.

The uterus has many functions. Its walls are equanimous of several layers of muscle which aid in transport of sperm to the oviduct following insemination and in expulsion of the calf at birth. Certain glands inside the walls of the uterus secrete a fluid, uterine milk, which provides nutrients to the developing embryo before and after its attachment to the uterine wall.

The uterus too develops the maternal side of the placenta to nourish and protect the developing fetus. Its surface contains many specialized areas chosen caruncles (Fig. 3). Cotyledons of the fetal placenta interlock (Fig. 3) with caruncles on the uterus to provide a passageway for the commutation of nutrients and waste material betwixt fetus and cow. Afterward calving, if the caruncles and cotyledons fail to unlock, the placenta cannot be expelled and a retained placenta (Fact Canvass IRM-21) results.

Oviduct

The oviducts (Fig. 1) are approximately ten inches long, 1/iv inch in diameter and lie between each ovary and tip of the adjacent uterine horn. The ovarian finish of the oviduct is funnel shaped and called the infundibulum. The infundibulum catches the egg every bit it is released from the ovary at ovulation and moves information technology to the enlarged upper end of the oviduct called the ampulla. Fertilization occurs here within 12 hours of ovulation. Subsequently fertilization, the fertilized ovum is transported to the uterus in a process requiring 3 to iv days.

Ovaries

The ovaries are the primary reproductive organ of the female person. In a dairy cow, each ovary is approximately 1.five inches long and 3/4 inch in diameter (Fig. 4). The ovaries are suspended from the broad ligament near the end of the oviduct and lie virtually the tips of the curved uterine horns. Their function is to produce the egg or ovum and hormones involved in regulating the estrous wheel and pregnancy.

The ovaries contain thousands of ova. These are produced by the embryo prior to birth. While the potential to collect hundreds of ova from a cow exists, only 1 ovum is usually released during each estrous cycle. When more than than 1 ovum is naturally released it can lead to multiple births—an undesirable effect considering of freemartinism. Nevertheless, superovulation, or the production of several ova following injection of hormones such as pregnant mare's serum gonadotropin (PMSG) or follicle stimulating hormone (FSH), is an essential element in embryo transfer.All ova are surrounded past a special layer of cells in the ovary. The growth of these cells produces blister-similar structures, called follicles, that are visible on the surface of the ovary (Fig. 4).

These develop continuously throughout the life of the cow and the vast majority backslide without releasing the ova. Evolution of ovulatory follicles begins at puberty. As the follicle enlarges, it appears as a large blister on the surface of. the ovary and tin can be easily detected by rectal palpation. This phase of activity is culminated past the release of ova from the follicle forth with the follicular fluids.

Following ovulation, the walls of the follicle collapse and develop into the corpus Iuteum (CL) or yellow torso (Figs. 4,v). The CL reaches its maximum size ten-12 days after ovulation and is the dominant structure on the ovary. If a pregnancy does non effect, the CL regresses 3 to iv days prior to the next ovulation. Nevertheless, the presence of an embryo in the uterus prevents this from happening.

Development of the follicle and subsequent formation of the CL are associated with the production of estrogen and progesterone, respectively. Estrogens are produced by the cells lining the wall of the follicle and are responsible for changes in behavior likewise as altering the production of fluids past the vagina, uterus and cervix. In addition, estrogens too trigger the release, from the pituitary gland, of the hormone responsible for ovulation, Iuteinizing hormone (LH).

Equally a event of these synchronized events, the moo-cow comes into rut, tin be mated, the fluids of the tract provide a favorable environment for survival of the sperm and ova, and ovulation occurs at the fourth dimension when sperm will be available to crusade fertilization.

Associated with ovulation is the transformation of the follicle wall into the CL under the influence of LH. The CL begins to produce progesterone which is required for maintenance of pregnancy. Progesterone acts upon the lining of the uterine wall to prepare information technology for subsequent attachment of the embryo. In addition, progesterone and depression levels of estrogen prevent resumption of normal cyclic action and permit for maintenance of pregnancy (Fact Sheet IRM-2).

Some other important function of the CL is the production of a hormone called relaxin. Relaxin relaxes the cervix and suspensory ligaments in the pelvic region prior to calving, producing the "springer" look. This relaxation of the neck is essential for the successful delivery of a new calf. Consecration of parturition with oxytocin prior to relaxation of the neck may result in impairment to the uterus because the neck may not relax sufficiently to let for passage of the dogie.

Pregnancy and the Reproductive Tract

Major changes in the ovaries, uterus and cervix occur during pregnancy. The presence of the CL on the ovary during pregnancy prohibits development of mature follicles. The uterus enlarges as do the sites of embryo zipper, the caruncles. In the non-pregnant cow these structures are approximately 1/two inch in diameter, but are 2-iii inches in diameter at calving. A thick mucus plug forms in the cervical culvert and is thought to protect the uterus from infections. The walls of the vagina and vulva are dry and white because of the lack of estrogens.

The relative position of the reproductive tract within the pelvic curvation also changes. As the embryo increases in size, the significant horn begins to drop over the rim of the pelvis into the trunk crenel and displaces the intestines. As it does then it stretches the ligaments and pulls the ovaries along with it. As a result, palpation of the ovaries during pregnancy may be hard. The uterine horn containing the embryo enlarges at a more than rapid rate than the "non-pregnant" horn which accommodates a portion of the placenta.

The birth process may be divided into two parts: the commitment of the calf and the subsequent delivery of the placenta or after birth in a process referred to as "cleaning." It must be remembered that the attachment sites of the placenta in the uterus consist of the maternal contribution, the caruncle, and a fetal side called the cotyledon. During pregnancy these tissues interlock with each other forming tight attachments (Fig. three).

When the dogie is born, the fetal placenta loses its source of nourishment, blood pumped by the calf heart. The loss of nutrients coupled with changes in the caruncle brought most by decreases in progesterone lead to a loosening of the zipper sites. The placenta is then passed by strong uterine contractions illicited past prostaglandins from the uterus and oxytocin released past nursing or milking.

Failure of the release mechanisms, due to hormonal imbalance, nutritional imbalances (Vitamin E & Selenium) or infections that crusade swelling of the tissues, results in a retained placenta (Fact Sail IRM-21). After "cleaning" occurs it takes the uterus xxx-40 days to render to its non-pregnant size and condition. Discharges during this catamenia are due to the repair of the uterine tissues and should be of trivial concern unless they incorporate pus. This would indicate the presence of a local infection that would require treatment (Fact Canvas IRM-22).

Abnormalities of the Reproductive Tract

Abnormalities may be classified as structural or functional and are estimated to account for x-20% of infertility in dairy cattle. A structural abnormality could exist the issue of abnormal embryonic development while functional abnormalities could be due to hormonal imbalances.

The most familiar structural abnormalities are seen in the freemartin. The birth of a heifer co-twin to a bull results in abnormal evolution of the heifer's reproductive tract. This condition results when the placentas of the embryos unite during pregnancy, allowing the two embryonic circulations to combine. Every bit a result, a substance responsible for organizing the male person reproductive system crosses into the female and inhibits the development of the ovaries.

In addition, the development of the oviducts, uterus, cervix and function of the vagina is blocked by a substance produced by the developing testis of the male. The degree of inhibition is related to the stage at which the placentas joined. The earlier the fusion, the more consummate the inhibition. Other abnormalities such as ii cervices, absence of one uterine horn, or blockage of the oviducts besides occur.

Functional abnormalities such as cystic ovaries (Fact Sheet IRM-25) or infections in the oviducts or uterus (Fact Sheet IRM-22) leading to the distention with pus are also common. While theories exist to explain the causes of these conditions, handling consists of hormone or antibiotic therapy.

Summary

The reproductive tract of a moo-cow is composed of the vulva, antechamber, vagina, cervix, uterus and ovaries. The ovaries, nether command of the hormones FSH and LH from the pituitary, mediate events of the reproductive cycle and reproductive tract through secretion of ovarian hormones, estrogens, progesterone and relaxin. The ovaries also release ova which carry the maternal genes. Structural abnormalities such as freemartinism, double cervix, etc. can impede reproduction. A lack of understanding of the beefcake of the reproductive tract can lead to poorer conception rates and lower reproductive efficiency.

Trade or brand names are mentioned merely for information. The Cooperative Extension Service intends no endorsement nor implies bigotry to the exclusion of other products which too may be suitable.

Jan 2007

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Source: https://www.thecattlesite.com/articles/1031/anatomy-of-the-cows-reproductive-tract/

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