1. Reproductive Physiology of the Female (ewe = female sheep, doe or
nanny = female goat)
Seasonally polyestrous, average 16 day estrous cycle in ewe and 21 days in doe, fall breeding season (decreasing daylength). In estrus 1-3 days, white discharge at end of estrus in doe. Gestation lasts 5 months: approximately 146 days in ewe, 150 days in doe. Ewe's placenta makes progesterone to support pregnancy after first trimester, but doe depends on corpus luteum for all of pregnancy.
Four rows of cup-shaped caruncles in each uterine horn. Cervix has 4 or 5 fibrous rings. Cervical rings of ewe are not in same line, making transcervical insemination difficult.
In the European dairy breeds, female goats that are homozygous for the polled gene (dominant gene for absence of horns) are sterile and show various anatomical malformations such as penile clitoris, ovotestes, small testes in scrotum, hypospadius. They usually develop the buck odor during the fall and behave like bucks. Polled goats that are heterozygous for the polled gene are fertile, even more prolific than horned goats. To avoid intersexes, always use at least one horned goat in a breeding pair.
Freemartins are not common in sheep or goats, but may occur if placentas of male and female cotwins fuse early in pregnancy.
4. Estrus Detection
Male is expert, smells estrous female from afar. Vasectomized or aproned male or intersex goat used if want to reserve for artificial insemination. Marking harness with colored crayon (change color every 14 days) used on ram or colored grease smeared on wool. Male goat has testosterone responsive scent glands caudomedial to horns; buck rag attracts estrous doe if no buck available.
5. Synchronization and Breeding
Male effect will synchronize onset of cyclicity at beginning of breedings season. More ovulations on second cycle, so can use vasectomized male or give prostaglandin 14 days after male first introduced. Vaginal sponges or progestogen implants are available in some countries, but Pregnant Mare Serum Gonadotropin (eCG) necessary for good fertility outside breeding season. Usually give prostaglandin when remove progestogen source. Photoperiod treatment (2 months long days in January followed by return to shorter day length) will stimulate cycling in the spring but not synchronize the cycles. Male should be kept separate but exposed to same photoperiod treatment.
Natural breeding most common: one fertile ram can breed 50-100 ewes on a flat pasture. Young ram often allowed 25 ewes. If use multiple rams, use an odd number (2 to fight while the 3rd one breeds).
Artificial insemination easy in goats - get 65-70% conception rate with frozen semen. In ewes, difficult to get pipette through cervix, though special equipment has been developed in Canada for transcervical insemination. In Australia and other countries where permitted, laparoscopic AI is routinely done in sheep.
6. Pregnancy Diagnosis
Check with male for return to estrus. Progesterone level at time of expected return to estrus is nonpregnancy test. Estrogens from the placenta can be used for pregnancy diagnosis. Radiograph possible after 3 months (Pygmy goat with dystocia). Amplitude-depth (A mode) ultrasound just detects fluid, unreliable in late pregnancy and of little value in goats, because of false pregnancy. Most popular test in UK and USA is real time ultrasound - transrectal 20-30 days after breeding, transabdominal after 35 or 40 days. Fetus or caruncles (cup or donut shape) proof of pregnancy. Use woolless areas in front of ewe's udder with ewe sitting on rump, or examine from right side while standing. Best if clip hair in this area of doe's abdomen for good contact of probe with skin.
7. False Pregnancy
Common problem in goats, especially if bred out of season (dairy goats) or kept unbred as pets. A corpus luteum persists in the absence of pregnancy; some were initially pregnant and resorbed the fetus, but unbred goats also develop false pregnancy. Often accompanied by hydrometra, with accumulation of fluid (but no caruncles) in uterus. May look large enough for triplets, develop an udder. Diagnose with real time ultrasound - recheck in few weeks if only a little fluid present. Spontaneous correction is called a cloud burst. Treat with 5 - 10 mg prostaglandin F2 alpha, repeat in 12 days.
8. Abortion Diseases
Suspect an infectious cause if more than 2% of flock aborts. Diagnosis requires laboratory examination of placenta and fetus; paired serology sometimes helpful. Precautions against zoonotic diseases, isolation of aborting female, removal of placentas and all fetuses not needed for diagnosis. Long-acting tetracyline may be prophylactic.
a. Chlamydiosis, Enzootic abortion
Chlamydia psittaci - zoonotic and reportable in Germany
If infected before or soon after birth, aborts during last 4-6 weeks of first pregnancy. Remains infected, sheds organism in vaginal secretions when in estrus but usually does not abort again for >3 years. Intercotyledonary areas of placenta thickened, organism is acid fast. FA of placenta, impression smears of umbilicus, stomach contents also diagnostic. Chlortetracycline in feed (200-500 mg/d) during last 2 months of pregnancy or long-acting tetracycline (20 mg/kg q. 3 days) to stop outbreak.
Toxoplasma gondii, from cats. Abortion at any stage of pregnancy, resorption, mummification, stillbirths, weak lambs, rarely abort twice. White 1-3 mm foci in cotyledons, dam remains seropositive for many months. Eliminate or neuter cats. New Zealand modified live vaccine used in UK.
Campylobacter fetus var intestinalis or var jejuni, from carrier ewes in endemic flock. Abortion rate of 10-90% in last 4 -6 weeks, fetus autolyzed and placenta normal, a few fetuses have round (target) liver lesions. Treat with chlortetracycline or penicillin/streptomycin, vaccinate in face of outbreak and vaccinate future replacement ewes.
d. Other Bacteria:
Listeriosis - Listeria monocytogenes from spoiled silage or intestinal carriers. Fetus is septicemic. Organism shed in milk. Retained placenta and metritis common. Rare to have neurologic disease in same outbreak.
Salmonellosis - any Salmonella species. Abortion, stillbirth, weak neonates. Ewe sick, febrile, has diarrhea and may die. Reduce environmental stress and feed in manger.
Leptospirosis - spirochetes in urine-contaminated water or feed. Late gestation abortion, autolyzed fetus. Ewe may be sick with nephritis or hemoglobinuria. L. hardjo has caused agalactia.
e. Q Fever - Coxiella burnetti. Shed in placenta at normal lambing or kidding or at abortion. Abortion in last 2-4 weeks, especially if other stress. Fetus autolyzed, placenta thick, treat with tetracycline. Zoonotic.
f. Bunyaviruses and Bluetongue - arthropod borne, cause damage to fetal brain, arthrogryposis.
g. Kirkbride's Bacillus - Flexispira rappini. Very difficult to grow, but occasionally found in late term abortions. Liver lesion resembles Campylobacter.
h. Nutritional Deficiencies - iodine deficiency or feeding cruciferous plants causes goiter, abortions, stillbirths.
i. Stress Abortions in goats, Inherited Abortions in Angora Goats - older does become habitual aborters. Selection for more mohair favors does with hyperfunction of adrenals. Don't save male kids for breeding from young doe.
j. Drugs - parbendazole and cambendazole proven teratogenic in sheep, levamisole suggested to cause abortion in goats. Avoid all unnecessary drugs in first 35 days of pregnancy.
k. Sheep x Goat Hybrids
When a buck breeds a ewe, the semen is usually not capacitated. When a ram breeds a doe, conception occurs but the hybrid fetus is usually rejected immunologically by 42 days. Very rarely these hybrids survive to term.
9. Pregnancy Toxemia - to be discussed in last lecture
10. Induction of Parturition
Use for convenience of owner or if late pregnant animal injured/unable to rise. Usually works too slowly in cases of severe pregnancy toxemia to save the mother.
In goats, 5 - 10 mg prostaglandin F2 alpha or 125 ?g coprostenol will cause delivery in approximately 30 - 36 hours, but best to wait until day 144. Sheep produce progesterone in the placenta, and more common to use estrogen (16 mg estradiol-17 beta) or corticosteroids (20 mg dexamethasone). Parturition in approximately 44-48 hours. Dexamethasone does not work dependably before day 139 in sheep, day 141 in goat - may choose this drug if exact breeding date unknown and trying to treat moderate pregnancy toxemia.
11. Dystocias and Prolapses
a. Vaginal Prolapse - late pregnancy. Etiology unclear, but short tail dock of ewe, genetic predisposition (cull animal and its offspring), inadequate exercise, excessive indigestible fiber in diet discussed as possible causes. Treat with truss or vaginal prolapse paddle; if vulva sutured, must remove sutures before parturition. If difficulty replacing prolapse, elevate prolapsus to empty bladder. Lidocaine/xylazine epidural. Often leads to C-section.
30-30-30 rule: examine the female if no progress has been made within 30 minutes after hard straining begins or part of the fetus or placenta shows. If all seems normal, wait 30 minutes more. Examine/assist if 30 minutes since last fetus delivered and another one still to come.
Be clean, Be gentle, Use lots of lube
Wear gloves - to protect mother from infection and shepherd or vet from zoonotic diseases
If anterior presentation, usually only need head and 1 front limb in position; if posterior presentation, usually only need 1 hindlimb in position. Head snare very useful. If fetus dead, cut off offending head with scalpel, remove limbs with subcutaneous fetotomy technique.
Ringwomb = failure of the cervix to dilate ? Cesarean section (prostaglandin, calcium). Cause unknown.
Uterine Torsion - feel twist in vagina if torsion caudal to cervix, roll with pressure on abdomen. Torsion ahead of the cervix resembles ringwomb - identify at C-section.
Cesarian Section - local or caudal epidural anesthesia (3 - 4 mg xylazine in 2 ml 2% lidocaine, wait 45 minutes). Tranquilize with blindfold, not drugs! Ventral midline or left flank incision, remove all fetuses through one incision in uterus. Postoperative antibiotics, tetanus prophylaxis, oxytocin (5 IU), analgesics (flunixin).
c. Uterine Prolapse - elevate rear end of ewe or doe, remove loose placenta and wash uterus, replace by pushing downwards into pelvic canal. Caudal epidural first, antibiotics and a mattress suture across the vulva for 2 days. OK to keep for breeding.
12. Retained Placenta
Usually passed within 12 hours, may be eaten by dam. Retention common after abortion (remove from pen - potentially infectious). Selenium deficiency a possible cause. Systemic antibiotics if systemically ill (tetracycline if abortion problem). Dairy goats seem more at risk for toxic metritis than sheep. Lochia (odorless, dam not sick) lasts 3 weeks.
1. Physiology of the Male (ram or tup or buck ?Texas? = male sheep; buck or billy = male goat)
Fertile at 3 to 6+ months of age, depending on breed. Production of LH and subsequently testosterone increased with decreasing day length. During breeding season, buck develops strong odor and urinates on his head and front legs. Males forget to eat and lose weight during breeding season.
Two relatively large testes placed vertically in scrotum. Head of epididymis is dorsal, tail ventral. Testes are oval. Penis initially has adhesions to the prepuce that break down under the influence of testosterone. A urethral process extends beyond the glans penis. Seminal vesicles have not received clinical attention.
3. Sperm Granulomas
Bucks that are homozygous for the polled gene (very smooth head) are initially fertile but often develop obstruction of the head of the epididymis because of blind efferent tubules that fill up with semen, rupture, mineralize. Palpate before each breeding season. No treatment.
4. Lamb Epididymitis
Gram negative organisms (Actinobacillus seminis, Haemophilus somnus) ascend from prepuce to epididymis or testis near puberty. Ram will not be usable for breeding. Prevent in problem flocks with 200 mg/head/day tetracycline in feed, 10 days each month.
5. Ram Epididymitis, Brucella ovis
In sexually experienced rams, which can be infected orally, conjunctivally, or venereally (homosexual behavior or with ewe as mechanical carrier). Organism passed in urine and semen even if no palpable enlargement or fibrosis of tail of epididymis. In ewes, get 1-2% abortions in infected flock, 1-2% stillbirths, 1-2% weak lambs, 5-7% singles instead of twins, 1-5% of ewes lamb late, 1-5% don't conceive. In total, get up to 20% increase in lambs if eradicate B. ovis from a flock. Cull if palpable epididymitis, positive serology (ELISA), or neutrophils and detached sperm heads in semen. Can also culture semen.
6. Breeding Soundness Exam
General health and body condition - teeth, feet, eyes. parasites, freedom from genetic defects. Observe mating behavior if possible. Measure scrotal circumference: normal depends on breed, age, weight, time of year. Should be > 36 cm for most mature rams in breeding season. Palpate testes within scrotum: "Big is beautiful, mobility is meaningful, resilience is respectable, softness is suspicious"
Collect semen sample with artificial vagina or electroejaculator. Creamy white, 1-2 ml, check motility and morphology with microscope ? keep sample warm, no exposure to water. Determine concentration with hemocytometer or centrifuge for spermatocrit. Can dilute in heat treated milk for artificial insemination.
7. Castration (wether = castrated male sheep or goat)
Not necessary in ram lambs and buck kids to be slaughtered before puberty. Improves flavor of meat of older animal and odor of goat. Techniques include rubber band, Burdizzo to crush spermatic cords twice on each side, open surgical castration. Local anesthesia with 1% lidocaine possible. Intentionally or unintentionally leaving a testis above an elastrator band (short scrotum) will not always make the animal sterile. Tetanus prophylaxis is necessary if no colostral antibodies against tetanus.