CCSS.ELA-Literacy.RH.9-10.7 Integrate quantitative or technical analysis (e.g., charts, research data) with qualitative analysis in print or digital text. CCSS.ELA-Literacy.RH.11-12.2 Determine the central ideas or information of a primary or secondary source; provide an accurate summary that makes clear the relationships among the key details and ideas. Next Generation Science / Common Core Standards Addressed!
Why is it necessary to collect semen from animals? Describe “good quality semen”. Why is semen extended? Explain the process of artificial insemination. Why are processes such as artificial insemination and embryo transfer useful? What is estrous synchronization? Is it beneficial? Explain rectal palpation. Bell Work!
The vast majority of range animals are bred by natural service. In other words the male mates directly with the female. In large confinement operations the use of artificial insemination eliminates the need for keeping a large number of sires (males) on hand. This reduces expenses and provides a safer work environment as many male animals are aggressive and dangerous to work around. Animal Breeding Programs
The first step in the process of an artificial breeding program is the collection of quality semen from the male animal. The collection of semen allows the producer to evaluate breeding soundness, to breed animals artificially, to store semen for later use and increase the number of females to be bred during a mating season. A male of any species can breed many more females (dam) increasing the genetic impact of a quality sire. It is very important to evaluate semen prior to storage for future use. Semen Collection!
When collecting semen from bulls and stallions there are risks to handlers working directly with these animals because of their size. To minimize risks, use proper restraint and be cautious. If using a female in estrus (heat) she also needs to be properly restrained especially when dealing with horses. Semen Collection
Sanitation is especially important when dealing with semen collection. Clean all equipment prior to the start of collection. Bacteria, antiseptics, debris and disinfectant that come into contact with the semen will affect its viability. Once semen has been collected it must be processed in a very timely manner. All equipment and supplies must be ready to complete the process of evaluation, dilution and storage as rapidly as possible. Bull and boar semen may be diluted and stored, whereas stallion semen may be diluted but is used immediately following collection and evaluation. Semen Collection Cont.
The method of semen collection used is determined by the species of animal to be collected. Methods may also vary from between species. The artificial vagina (AV) is the most common method of “catching” the semen, because it is a more natural method. The AV is made from a rigid tube with an inner liner generally made of latex which is filled with water at body temperature of the animal to be collected. Temperature and pressure of the tube maintain pressure on the males penis which is very important in the collection process as it simulates natural service. Methods of semen collection.
The electroejaculator is a device that sends electrical impulses through a probe inserted in the male’s rectum adjacent to the accessory sex organs. Stimulation of these organs results in protrusion and erection of the penis followed by ejaculation. Semen is collected in a tube by one of the handlers. Electroejaculation is generally reserved for untrained males or males with poor libido. Methods of semen collection cont.
Bulls and rams may be collected with an AV, electroejaculator, or by massage. Trained bulls at an AI Stud will mount a cow in or estrus or generally a dummy. Stallions are collected using an AV device. Studs are trained to mount a dummy in most cases but occasionally a mare will be used with the penis diverted into the AV. Most boars are collected using an AV device suitable for their size. In most instances a boar will mount a dummy for collection. Dogs and cats may be collected by manual stimulation and collected in an AV device. Semen Collection
Semen is evaluated macroscopically ( by the naked eye) and microscopically with a microsope. Macroscopic evaluation includes visualization of color, volume and debri. Semen volume will vary from one individual to the next as will the concentration of sperm cells. Semen Evaluation.
Microscopic Evaluation Microscopic observation evaluates the sperm cells motility, concentration and sperm morphology. Generally sperm cells will swim in one direction, there may be a few abnormal cells. Excessive numbers of abnormal cells will affect movement within the females reproductive tract.
After microscopic evaluation is complete the semen will be diluted. The dilution process is generally referred to as extending. The purpose of extending semen is so that a number of females may be bred from one collection of an outstanding male. Once the semen has been extended it is ready for storage. With cattle is frozen in small straws placed in liquid nitrogen and may be kept indefinitely, swine semen is placed tubes in chilled storage is may be viable for a week. Stallion semen is generally used immediately. Semen may be sexed but this process is not commonly used. If using frozen semen is used it should be thawed quickly for use, often in a warm water container. Semen processing
Artificial insemination is the placing of semen collected from a male into the reproductive tract of the female by a method other than natural service. The purpose of AI (artificial insemination) is to maximize the value of outstanding sires. This allows a number of animals to be bred(perhaps thousands) to an individual sire that would otherwise be unavailable to the ordinary producer. AI was first performed by Arab horsemen in the 1300’s, an Italian scientist by the name of Spalanzinni bred dogs artificially in the 1700’s. Russian scientists did extensive research before AI became an accepted process in the US. In 1949 scientists developed a process where semen may be frozen for future use. Artificial Insemination
AI is used in many classes of domestic livestock. Semen collected from Boars, Stallions, Toms and Roosters is generally used fresh because it does not freeze well. Most domestic poultry is bred artificially because improved breeding yields chickens and turkeys with breast muscles that are so large that natural service is no longer possible. Both dairy and beef semen is frozen. Well over 90 % of all dairy cattle in the US are bred artificially. Artificial Insemination Cont.
A cow in standing heat is chosen for breeding Straws of semen are retrieved from the liquid nitrogen tank. Semen is thawed if frozen. The thawed semen is placed in the insemination device. The inseminator puts on an arm length plastic insemination glove on one arm. The gloved hand and arm are inserted into the cows rectum. The reproductive tract is grasped through the wall of the rectum. In horses the arm is inserted directly into the mares reproductive tract. The insemination device is inserted into the reproductive tract through the cervix into the uterus where the semen is deposited. The tissues in the horses repro. tract are more delicate than those of cattle and greater care should be taken during the breeding process Artificial Insemination in Cattle/ Horses.
A sow or gilt that is in heat is selected of the insemination process. The breeding rod is inserted into the repro. tract. Upon contact with the cervix the rod should be turned clockwise so that it will actually thread the cervix of the female. When the breeding rod is snugly in place elevate the rod attach the tube of semen to the breeding rod. Slowly/gently squeeze the bottle until all of the semen has entered the breeding rod. Turn the rod counter clockwise until it is free and remove it from the female. Artificial Insemination In Swine.
Estrous synchronization involves the administration of synthetic hormones to females to control when they will be in standing heat (estrus). The purpose of estrous synchronization is to allow the producer to control when the female will deliver her offspring. Knowing when an animal will deliver will allow the producer to prepare for delivery and observe animals more closely than normal Estrous synchronization
Embryo transfer in cattle has gained considerable popularity. Embryo transfer technology was developed in the 1970’s and 1980’s but has really become common place in the late 1990’s. Historically the first embryo transfer took place in rabbits in the 1890’s, it was a surgical process which is not applicable today. The purpose of embryo transfer is to move the fertile embryo from and high quality cow bred to an outstanding bull to a “donor” a grade cow to serve as the surrogate mother. It is estimated that a cow may have 150,000 “eggs” within her ovaries, by natural breeding only a small percentage of these eggs will yield a calf. As a result of embryo transfer one cow has the potential to yield hundreds if not thousands of fertile embryos. Embryo transfer in cattle.
Steps in the embryo transfer process. Step 1 is the selection of a quality donor cow. The calves need to be of sufficient quality to cover the cost of the process. Step 2 - superovulation of the donor cow. Superovulation is the stimulation via hormone treatment ant the release of multiple eggs in one estrus. Properly treated cow will yield ten or more viable embryos. Some high quality cows are treated on a regular 60 interval schedule. Step 3 – insemination of the cow. Due to the high number of ova released it is a good idea to breed the cow more than once. Cows are usually artificially bred on a 12, 24 and 36 hour schedule. Step 4- Flushing the cow. The embryos are collected non-surgically. A catheter is inserted into the cows uterus where saline solution is used to flood the entire uterus. As the fluid drains the embryos are removed and collected in a graduated cylinder. Embryo Transfer Cont.
Step 5 – Evaluation of the embryos. Embryos may be used immediately or frozen for future use. Each individual embryo is evaluated for: Regularity of shape Variation in cell size Color and texture of the cytoplasm (fluid in the cell wall) Embryo diameter Embryo Transfer Cont.
The most common pregnancy test in cattle is the “palpation per rectum “ method. It is similar to AI in cattle that the operator will insert a gloved are into the cows rectum and “palpate” feel through the rectum wall to touch the reproductive tract to determine pregnancy. In stage one – the operator will be looking for an enlarged uterus, stage two- feeling for connective cotyledons, stage three – feeling for a calf. Pregnancy testing in cattle!
Animals other than cattle area pregnancy tested using instrumentation. Basically a sonogram the same instrumentation used in humans. Pregnancy Testing Cont.