Fertilization, Pregnancy, and Parturition of Goats

[Audio] Fertilization, Pregnancy, and Parturition of Goats Presented bv Stephen Famatigan.

[Audio] Fertilization Goats are known to be seasonal breeders. They come to heat only during cool months when the day length is short. In the Philippines, this is usually between September and February. For goats to give kids year- round, they need to be in heat even during summer..

[Audio] The estrous cycle in goats is 21 days, on average, but can vary with different breeds or environmental conditions. A relatively high frequency of short cycles is characteristic of goats and tends to occur in young does and earlier in the breeding season. Longer cycles may be observed later in the season when does are transitioning into anestrus..

[Audio] Physiology and endocrinology of the estrual cycle of the goat The ovarian cycle is classically divided into two phases: follicular phase and luteal phase. The follicular phase corresponds to the wave of follicular development that will provide the ovulatory follicle and involves the maturation of follicles that are dependent on the gonadotropins until ovulation. During the follicular phase, FSH secreted by the anterior pituitary stimulates follicular growth. A cohort of antral follicles, which are gonadotropin dependent and with a diameter of 2– 3 mm, is recruited, and the follicles enter their terminal phase of growth..

[Audio] Only two to three of these follicles reach a size of 4 mm in diameter and are selected to enter the dominance phase. Under the influence of LH, the follicles reach the preovulatory stage ( 6– 9 mm), while the subordinate follicles degenerate ( follicular atresia). The increase in the peripheral concentrations of estradiol 17β causes a positive feedback effect on the hypophysis-gonadotropin axis, due to the follicular growth inducing the goat's estrus behavior..

[Audio] The consequent increase in gonadotropin-releasing hormone ( GnRH) secretion induces an increase in the preovulatory LH peak, which will induce ovulation between 20 and 26 hours later, and finally the luteinization of follicular cells will occur. The beginning of the follicular phase, before the estrual behavior is observed, is known as proestrus. The estrus phase includes the events of the sexual behavior of the goat until ovulation. Consequently, a response to estrus and ovulation will mainly depend on the time of pregnancy and nutrition..

[Audio] Whereas providing the goat with short energy supplementation can increase the rate of ovulation. During the estrus cycle, the ovaries undergo a series of morphological (follicular recruitment and growth), biochemical ( follicle maturation), and physiological (endocrine regulation) changes, which lead to ovulation. These cyclic changes that take place in the gonads are known as ovarian cycles. For follicular growth, it develops in the form of waves throughout the cycle..

[Audio] A follicular wave is characterized by the sequence of three gonadotropin-dependent events: recruitment, selection, and dominance. When performing repeated ultrasound studies, one can mention and/or suggest that there are between two and six waves of follicular development during the estrus cycle; in goats, there are usually three–four waves. The last follicular wave is the one that is going to give rise to the ovulatory follicle. When double ovulations occur, they are due to follicles derived from the same wave but two consecutive follicular waves.

[Audio] Also, the luteal phase begins when the corpus luteum is formed after follicle luteinization (duration 16 days). During this phase, LH is released pulsatile and, its frequency is negatively correlated with progesterone. Now, progesterone has a negative feedback effect on LH. Luteolysis begins around day 16– 17 of the estrus cycle, releasing uterine prostaglandins, influenced by oxytocin. With the above, the concentration of progesterone decreases, causing a strong increase in the frequency of pulses of LH and its amplitude, which causes ovulation.

[Audio] The mean duration of standing estrus has been reported to be 36 hours, although it can range from 24– 48 hours depending on age, breed, season, and presence of a male. Breed-specific mean estrus duration has been reported for Mossi ( 20 hours), Angora ( 22 hours), Creole ( 27 hours), French Alpine ( 31 hours), Boer ( 37 hours), Nubian ( 42 hours) and Matou ( 58 hours) goats..

[Audio] Estrus detection is based on behavioral signs, bleating, flagging of the tail, reddened vulva, vaginal discharge (which causes the tail hairs to stick together), and occasional " riding" by other does. These behaviors are more pronounced in the presence of an intact male..

[Audio] The external symptoms of estrus that can be mentioned as important are goats move the tail, increase vocalizations, decrease appetite, mount between them, increase urine excretion, inflammation of the vulva, and discharge of vaginal mucus..

[Audio] Ovulation can occur anywhere from 9– 72 hours after the onset of estrus, typically toward the end of standing estrus. The ovulation rate varies based on breed, season, and nutritional status. Angora goats typically experience a single ovulation period; however, they may have two if sufficient nutrition is available. The mean ovulation rate has been reported to be 1.7 eggs per doe in Boer goats and 1.5 in Maure goats..

[Audio] Pregnancy Determination in Goats Pregnancy determination in does is commonly performed using real-time ultrasonography to visualize the presence of an embryo/ fetus and placentomes within the uterus. Transabdominal ultrasound is quick and reliable and can detect pregnancy as early as 30 days, though it is most accurate after 45 days gestation. If possible, does should be fasted from food ( 12 hours) and water ( 4 hours) to improve speed and accuracy when performing ultrasonography in large herds..

[Audio] Transrectal ultrasound is more difficult and time consuming although it can diagnose pregnancy as early as 20 days. Ultrasonography can be used to count embryos/ fetuses most accurately up to 85 days gestation, which is important when managing does prone to pregnancy toxemia in late gestation. Fetal sexing may be performed by skilled ultrasonographers between days 55 and 70 of gestation and is more accurate in singles versus multiples. Radiography can be used to detect pregnancy with 100% accuracy after day 70 and can detect the number of kids after day 75, though is not routinely performed because of impracticality and cost..

[Audio] Progesterone concentrations can be measured in milk or serum. Samples must be collected precisely one cycle ( 19– 24 days) after the doe is bred. Whereas low progesterone levels can confirm that a doe is not pregnant, high progesterone is not a positive pregnancy test, because it cannot differentiate between midcycle, true pregnancy, or pseudopregnancy..

[Audio] Additionally, progesterone concentrations cannot accurately determine viability or predict fetal number when performed early in pregnancy. However, if measured at > 3 months gestation, progesterone concentrations have been reported to be higher in does bearing triplets then in does bearing twins or single fetuses..

[Audio] Pregnancy in Goats Gestation length in goats is 145– 155 days (average 150 days) and can be affected by breed, litter weight, environment, and parity. Generally, first-kidding does have one or two kids, and in subsequent kiddings, triplets and quadruplets are not uncommon. Progesterone production for maintenance of pregnancy depends entirely on the corpus luteum, with a drastic decline in progesterone occurring 12– 24 hours before kidding..

[Audio] Pregnancy toxemia in goats is similar to that in sheep. This condition occurs during the final 6 weeks of pregnancy, when 80% of fetal growth occurs and energy demands are highest ( 150X– 200X maintenance). Despite the increased energy demand, the growing uterus begins to restrict rumen capacity, reducing feed intake and predisposing does to developing ketosis. Does at increased risk of pregnancy toxemia include those that are over- or underconditioned and those with multiple fetuses. These does should be closely managed by increasing concentrate feed and monitoring urine for ketones throughout the last 6 weeks of pregnancy. Oral propylene glycol may be administered daily to does that develop subclinical ketosis to prevent progression of disease..

[Audio] Does that develop severe ketosis will become anorexic and recumbent and develop neurologic signs due to hypoglycemic encephalopathy and secondary polioencephalomalacia. If untreated, does can die quickly. Treatment protocols depend on the value of the dam versus kids; however, induction of parturition is recommended because the viability of fetuses is already compromised. Intensive supportive care of the dam should include administration of intravenous fluids with dextrose, insulin to inhibit fatty acid mobilization, and anti-inflammatories. Vitamin B12 may also be administered as an appetite stimulant. Parturition can be induced using PGF2alpha alone; however, adding dexamethasone will promote fetal lung maturation and maximize chances of kid survival..

[Audio] Lactational ketosis is similar to pregnancy toxemia but occurs within the first 3 weeks of lactation in high-producing dairy goat breeds. Clinical signs include irritability, anorexia, reduced milk production, and weight loss. Treatment options are the same as for does with pregnancy toxemia, depending on severity..

[Audio] Hypocalcemia or milk fever occurs in high-producing, older (> 3 years) dairy goats but not nearly so frequently, nor as severely, as in cattle. Early signs include stiff gait, tremors, and ataxia that can progress to complete recumbency, a comatose state, and death if untreated. Immediate treatment requires intravenous administration of calcium gluconate or calcium borogluconate solution, followed by oral or subcutaneous calcium for prolonged absorption. Treatment may be repeated in 24 hours for high-producing does if indicated..

[Audio] Vaginal prolapse is fairly common in does and is believed to have a hereditary component. It may intermittently occur during late pregnancy due to increased intra-abdominal pressure and can be managed by decreasing rumen fill (increasing hay quality and supplementing with grain toward the end of pregnancy). If complete vaginal prolapse occurs, intervention is required to prevent injury, infection, or dystocia. Caudal epidural administration and placement of a prolapse paddle, retention harness, or retention sutures are recommended; owners should observe animals closely for parturition. Owners should be advised that vaginal prolapses will recur with each pregnancy, so they can decide whether to cull the animal..

[Audio] Parturition in Goats Parturition tends to be uneventful in goats, with the incidence of dystocia < 5%. Induction of parturition is a useful technique to increase survival in dairy goat kids and to catch and separate kids from dams before they suckle in herds with control programs for caprine arthritis and encephalitis virus and mycoplasma. Induction with synthetic PGF2alpha analogues such as cloprostenol ( 125 mg) or dinoprost tromethamine ( 10 mg) usually results in delivery of kids ~ 30– 35 hours after injection, whereas dexamethasone ( 20 mg) requires ~ 48 hours to induce kidding. Viability of multiple fetuses may be compromised if parturition is induced before day 144..

[Audio] If the doe has been in active labor for 30 minutes with no progress, assistance is likely required. Most kids present cranially, in dorsosacral position, with front limbs extended. If kids present caudally, which is more common in twins, triplets, and quadruplets than in singletons, assistance for delivery is more likely to be required. The most common cause of dystocia is when two or more kids present simultaneously, which requires an experienced practitioner to identify and correct. Other causes of dystocia in does include malposition, fetomaternal mismatch, failure of cervical dilation ( ringwomb), vaginal prolapse, uterine torsion, and uterine inertia. Most dystocias can be corrected by repositioning kids and providing lubrication and traction. However, in more severe cases, fetotomy or cesarean section may be necessary..

[Audio] When assisting with kidding, extreme care must be taken to prevent uterine tears, which can be diagnosed on palpation of the uterus after the dystocia. Small tears (< 1 cm) can be treated by hastening involution of the uterus with oxytocin administration. Larger tears may require surgical intervention to minimize excessive bleeding and peritonitis. Systemic antimicrobials, anti-inflammatory drugs, and a clostridial vaccine booster should be administered to does after a prolonged dystocia..

[Audio] Retained placenta (defined as placenta not passed 12 hours after parturition) is uncommon in goats and is usually associated with selenium deficiency, the birth of a mummified or rotten fetus, or a difficult delivery. It can be treated by gentle traction or oxytocin administration to facilitate expulsion; however, diagnosis and treatment of the underlying cause will usually solve the problem..

[Audio] Metritis is almost always a sequela of dystocia and/or retained placenta, and systemic antimicrobials are warranted. Clostridial organisms ( Clostridium tetani and C perfringens) may colonize the uterus, resulting in a frequently fatal toxemia that requires aggressive supportive care, antimicrobials, and antitoxin therapy. Less severe causes of metritis may lead to a chronic endometritis and cause infertility if not treated..

[Audio] Uterine prolapse is uncommon in goats but may occur after dystocia. Treatment is similar to that in other species, and prognosis is good if recognized and treated early..

[Audio] Preparing for Kidding Kidding may occur on pasture, or you may need to provide does with a clean, dry, well-ventilated shelter, depending on the weather in your area and your preference. It is wise to watch animals carefully, in case they should require assistance. Straw or pine shavings, or an inexpensive hay, can be used for bedding in shelters, if desired. Pregnant animals will get an enlarged udder starting one to six weeks prior to kidding. Some signs that parturition, or kidding, is approaching include hollowness on either side of the doe's tail, the doe isolating herself from the rest of the herd, and an enlarged udder and teats that begin to fill with milk..

[Audio] At two weeks prior to kidding, the muscles of the ligaments on both sides of the doe will begin to soften and relax. During the last three to four days before labor, the udder will appear quite large as it fills with milk. Does that kid for the first time may not show this development until two weeks or more after kidding. One to two days before labor, the teats become enlarged and look full of milk; the does will begin to show signs of nervousness: pawing at the ground, acting restless, and lying down. The doe will also expel a thin mucous discharge from the vulva, which will gradually become thicker as parturition approaches. The last 12 hours of labor may consist of continuous bleating sounds by the doe. The tail may be straight out or slightly elevated. The first several vertebrae of the spine in front of the tail head may appear to stand higher and taller than usual..

[Audio] A normal delivery usually takes five hours. Cervix dilation (which you cannot see) usually requires four hours, and then one hour is required for the delivery of the offspring. The kid should be right side up with the front feet first, with legs extended and the head lying between the knees and pasterns in a "diving" position. After the water sac breaks, the doe should start to give birth within 30 minutes to one hour. If the doe is pushing very hard for longer than 30 minutes and a water sac or kid does not appear, it may be necessary to assist the doe yourself or contact a veterinarian for further assistance. Generally, if the doe is still in active labor and is pushing after having a kid and does not pass placenta or another kid within 30 minutes to one hour, assistance may be needed. Some does may take longer between kids without problems. If they are up cleaning a kid and appear comfortable, longer than one hour may be acceptable. Goats may have three, or rarely, more kids. The process will repeat with each kid..

[Audio] When the kid is born, try to let the cord break naturally, but if the sac is not broken, break it for the doe. Newborn kids are stimulated by the doe licking it clean. Normally, kids begin to vocalize as the doe cleans them. Normal kids attempt to stand within a few hours after birth and look for the udder to nurse. Respiration in the kid is stimulated by the doe licking the kid. If the kid appears lifeless, vigorously rub the kid with a towel to stimulate respiration and clean out the mucus from the nose and mouth with a finger or soft cloth. Placing a piece of straw up the nose, which will trigger a sneezing reaction, can also help clear the airways. If the kid is still having problems, giving it short, firm, but gentle, compressions with the fingers in the middle of the heart until it cries may help. Once the doe has kidded, make sure she has shed her placenta..

[Audio] Dystocia Normal presentation of the kid is two front legs and nose forward in a diving position. If there is any variation in the presentation of the kid, then the delivery will not be normal..

[Audio] Normal Kidding Position. Normal Kidding Position.

[Audio] Breach kidding Abnormal presentations include a kid position that is fully breached, with the buttocks or back feet appearing first. If the back feet appear first, no assistance is needed. If the buttocks/ tail is presented, the kid can be pushed back some, the back feet can be eased up into the position shown below (protect the uterus from puncture of feet using your hand), and kidding can be assisted if needed after that. A person assisting the doe should trim his or her nails, remove all jewelry ( rings), and put on latex gloves or thoroughly wash his or her hands. Antibiotics may be needed for does that have been given assistance, depending upon the severity of the problem..

[Audio] Breach kidding Position Another abnormal position may include the head presenting itself, with one foot visible, and the doe straining unproductively..