Small Ruminant Reproduction

sihirlifil's version from 2017-10-04 16:54

Comparative reproductive anatomy & physiology

Question Answer
Type of uterus:Bicornuate
Type of cervix:Fibrous (rings) (same as cow)
If you see pigmented caruncles...This is normal! Have melanocytes inside caruncles, vary from light to dark. Common in sheep, rare in goats
(Special about muskox caruncles?)(Pigmented with lipofuscin instead of melanin)
What is the cervix like in a sheep?Fibrous folds directed towards the vagina that interdigitate intimately
What is the cervix like in a goat?Fibrous folds directed towards the vagina that interdigitate less intimately
Why is it easier to perform transcervical AI in the goat?Fibrous folds of the cervix interdigitate less intimately than sheep
Function of urethral process? (aka filiform/vermiform appendage)Spray semen into & around the cervix during natural service
Problem with urethral process?Common site for lodging of uroliths (other = sigmoid flexure)
When are SR in season?Seasonally polyestrous, short-day breeders
What triggers the cycle?Decreased daylength --> Increased melatonin (pineal gland)--> Increased GnRH (hypothalamus)
For breeds closer to the equator, how is their cycle different?Cycle year round!
Factors affecting onset of pubertyBreed
Body weight
Season of birth*
Health status
How does season of birth affect onset of puberty?Lambs/kids born late in spring reach puberty a year later than those born early in spring
Duration of estrous cycle: Ewe16-17 days
Duration of estrous cycle: Doe20-21 days (same as cow)
Duration of estrus24 (20 in doe)-40 hours
Time of ovulation30 (12 in doe)-36 hours after onset of estrus
As opposed to the cow, ovulation happens when related to estrus?During (towards the end)
Cow happens afterwards

Reproductive management

Question Answer
Breeding management depends on:Photoperiod
Effect of environmetal temperature
Effect of nutrition
Ram-buck effect
How is the photoperiod controlled?"Light-tight" barns... not really practical
Melatonin in feed, or as subq implants (advance breeding season)
How does environmental temp affect breeding?Housed outside: 26% oocytes fertilized (lower), 49% embryonic death (high!), 13% ewes lambing (lower)
Air-conditioned: 64% oocytes fertilized (higher), 22% embryonic death (low), 50% ewes lambing (higher)
What is 'flush feeding?' High energy ration beginning 2-3 weeks prior to onset of breeding season
How does flush feeding affect breeding?Increases ovulation rate (chance of producing twins/triplets)
Something to keep in mind when flush feeding?Response influenced by body condition score at time of flush feeding. So, increase energy level in overconditioned animal = no increas, best response if undernourished
Causes of stress that can affect breeding?Disease
Lactation ((prolactin has neg feedback with GnRH, not cycling)
Suckling stimulus
**How does ram/buck effect affect breeding?Synchronize & advance
Most powerful stimulus for hastening onset of breeding season (within 3-4 days!)
Ram/Buck effect: how does it work?Introduce novel ram/buck
Ewes/does must be isolated from sight, sound & smell for 4-6 weeks prior to indtroduction
Teaser males (infertile) can be used first to induce cyclicity, followed by exposure to fertile males
Types of accelerated breeding programsThree-in-two (3 births in 2 years)
Five-in-three/Star system (5 births in 3 years)
Accelerated breeding is used to...Have multiple offspring in 1 year
Issues with accelerated breeding programsCan't really use with seasonal breeds (need more hormonal stimulation)
Needs better management, more manpower
Five-in-three: segments split how?5 sements of 73 days (half the gestation period)
Benefits of concentrating breeding & lambing/kiddingEfficient use of labor, facilities, pastures
Facilitates implementation of AI programs
Induction of estrus during off-season (continuous supply of meat & milk)
Better supervision during lambing/kidding (reduces perinatal mortality, increase success in cross-fostering lambs*)
What is cross-fostering?Distribute lambs to get better nourishment (e.g. undernourished ewes with triples: spread out to ewes that had only 1 or had mortality)
Rub lamb in placental fluids to trick
Estrus synchronization methodsRam/Buck effect
Hormonal methods of estrus synchronization:Prostaglandin F2a analogs --> estrus in 2-3 days
Progestins CIDR: elongate diesetrus (exogenous P4, sudden withdrawal)
PGF2a only used in cycling females because?Action depends on presence of corpus luteum
**How to give PGF2a? why this way?2 IM injections 9-11 days apart
2 injections to catch all females no matter what cycle- if only 1 injection, some animals may be too early/late for effect
PGF2a: synchronized estrus within ___ 2-3 days
**Progestins: how are they delivered?Controlled internal drug release (CIDR) intravaginal
Progestins: synchronized estrus within ___ 48 hours after removal
Signs of estrusSlightly swollen & congested vulva
(Difficult to detect)
How to identify ewes in estrus?Teaser with marking harness (after getting mounted, females get markings on rump = stood to be mounted)
Methods of AI in sheepFresh semen
Frozen semen
Fresh semen AI in sheep:Vaginal insemination (shot in the dark!)
Cervical insemination (need speculum & light source)
Frozen semen AI in sheep:Laparascopic intrauterine insemination = Put ewe in breeding cradle, hole in abdominal wall, deposit tiny amount of semen right in uterine horn. More invasive, takes expertise, need special equipment
Guelph system for transcervical AI (GST-AI) = bent-tip pipette through cervix. Can damage cervix, need training... going out of favor
RamGO device = thread into os cervix, load semen straw in semen pipette, most of semen goes into uterus
Methods of AI in goatsVaginal AI
Cervical AI
Transcervical AI (Visualize os cervix, put pipette through, inject semen)
Laparascopic intrauterine

Parturition & dystocia

Question Answer
Avg gestation length146 days (sheep); 150 days (goat)
Maternal recognition of pregnancy by:Elongation of conceptus & Interferon-tau (same as cow)
Days until maternal recognition of pregnancy:Day 12-13 (sheep); day 15-17 (goat, same as cow)
SHEEP: ___ essential for maintenance of pregnancyCL UNTIL DAY 55-70 then fetoplacental unit takes over
GOAT: ___ essential for maintenance of pregnancyCL THROUGHOUT GESTATION
T/F You can give PGF2a to a sheep at any stage of gestation to terminate pregnancyFALSE! Won't work after fetoplacental unit takes over (55-70 days) so need corticosteroids
**Pregnancy diagnosis:US
Can be performed day 30, more accurate after 45-50
Stage 1 parturitionSwollen vulva, restless, uterine contractions, dilation of cervix
Stage 2 parturitionCervix open, fetus enters birth canal, 1st water bag (allantois) then the 2nd water bag (anmion) rupture. Expulsion of fetus
Stage 3 parturitionExpulsion of placenta about 2-3 hours later
When to intervene during parturition?Around 45 minutes if no progress
**Most common causes of dystociaPostural abnormalities
Simultaneous presentation of multiple fetuses
Normal presentation/positio/pattern?Cranial longitudinal presentation, dorsosacral position, extended FL & flexed HL pattern
**True Ringwomb =Incomplete dilation of the cervix unresponsive to manual stimulation
Cause is unknown (hypocalcemia, phytoestrogens...?)
Tx for ringwombC-section only option!
**Hydrometra: common in who? What happens?Most common in goat
Pseudopregnancy (Abdominal enlargement, persistence of CL & accumulation of sterile watery secretion in the uterus)
Cloudburst = spontaneous evacuation of large amounts of fluid
Treatment for hydrometraPGF2a analogs
After hydrometra, fertility = ?Variable

Important reproductive conditions

Question Answer
Vaginal prolapse occurs when?During gestation prior to parturition!
Causative factors of vaginal prolapseIncreased intra-abdominal pressure from advanced pregnancy
Relaxation of perineal tissues close to term
How to treat vaginal prolapseReduce, replace, retain! Epidural, clean & replace prolapsed mass, retention using different devices (U-saver/prolapse paddle, rope truss, Buhner suture) (take out retention devices before lambing!!!)
Uterine prolapse occurs when?Postpartum
Predisposing factors for uterine prolapseDystocia
Hypocalcemia (uterine inertia)
How to treat uterine prolapseEpidural anesthesia, reduce, replace, retain the prolapsed mass, Buhner suture
**Pregnancy toxemia caused by?Negative energy balance, especially with multiple fetuses = Increased energy demand especially during last 3rd of gestation
Inadequate energy intake from diet
Stress (bad weather, transport, concurrent disease) precipitate other underlying reasons
CS of preg toxDepression, lethargy
Ketotic breath
Neurologic signs: apparent blindness, tremors, torticollis
**Dx of preg toxHistory: close to term, multiple fetuses
Clinical signs
Ketonuria (Dipstick)
Serum biochemistry
Tx of preg toxSupply mom with energy precursors (Oral propylene glycol, glucose & electrolytes, IV dextrose)
Correct acidosis & electrolyte imbalances (IV LRS, sodium bicarb)
Induce parturition: PGF2a/Dexamethasone or C-section
Components of ram/buck BSEHistory
General PE (eyes, feet, teeth)
Reproductive exam
Semen collection & evaluation
Venereal diseases
BSE: what are you checking for in the repro exam?Pizzle rot, uroliths, epididydimitis, sperm granulomas
BSE: which venereal diseases are you checking for?B. ovis (serology)
Causes epidydimitis, orchitis, sperm granulomas, abortion in ewes
(B. ovis correlated with what sperm abnormalities?)Seminal leukocytes, detached spermatozoal heads
Criteria for passing the BSE (Satisfactory)Scrotal circumference above threshold for age (highly correlated with # spermatozoa produced)
Semen motility >30%
Normal spermatozoa >70%
B. ovis free
Congenital penile abnormalitiesHypospadia (uncommon)
Short penile length (uncommon)
Other: Gynacomastia
Congenital testicluar & epididymal abnormalitiesTesticular hypoplasia
Cryptorchid (uncommon)
Acquired penile abnormalitiesUrolithiasis & urethral rupture
Balanoposthitis (pizzle rot)
Hair ring
Scrotal mange (uncommon)
Acquired testicluar & epididymal abnormalitiesOrchitis
Sperm granulomas
**Balanoposthitis (pizzle rot): more common in? Causative agent? What happens?More common in castrated wethers than rams
Corynebacterium renale most common cause, high protein diet/ lush pastures predispose
Scalding of preputial region & penis from urea produced by the bacteria
Balanoposthitis: CSPainful urination (dribbling)
Kicking at abdomen (pain)
Scabs (from necrosis) at preputial orifice (can close)
Balanoposthitis: txMild: restrict dietary protein/access to lush pasture, shear area, dilute H2O2
Severe: acidify urine with ammonium chloride, irrigate prepuse with mild antiseptic, broad spectrum antibiotics
Phimosis: causes?Usually 2ry to trauma or balanoposthitis, can be congenital (permanent unsoundness)
Phimosis: txManually break down adhesions, NSAIDs (flunixin), Penicillin, preputial lavage
(Must ddx from pre-puberty conditions that can be normal)
Paraphimosis: causes?Trauma, balanoposthitis
Paraphimosis: txPreputial lavage 2/ mild antiseptics, antibiotics & corticosteroid cream applied to penis, replace penis in prepuce & close the preputial opening with purse-string with tube for urine drainage; penile hydrotherapy; sexual rest
Paraphimosis: prognosisPoor in prologned cases (>2 weeks)
Orchitis: more common in? causes?Bucks
Trauma, infection
Orchitis: CS?Hot, painful, swollen testis/teses, asymmetrical on palpation
Pain on walking, decreased libido
Orchitis: treatmentAntibiotics, NSAIDs
If unilateral in valuable breeding animal, CONSIDER HEMIORCHIDECTOMY SOONER RATHER THAN LATER so infection doesn't spread to other side! (B. ovis: cull, can cause abortions)
**Epididymitis: more common in? causes?Rams
Primary disease or secondary to orchitis (unilateral or bilateral)
Epididymitis: results in?Impaired semen quality (maturation affected), epididymal obstruction & sperm granuloma
**Epididymitis in older rams: pathogen?Brucella ovis
**Epididymitis in younger rams: pathogens?Histophilus, Actinobacillus, Haemophilus, Corynebacterium pseudotuberculosis
Epididymitis: transmission in young vs older?Young = contagious veneral disease, older = environmental conamination
Epididymitis: CS?Acute: hot, painful swelling (asymmetrical especially in tail)
Increased neutrophils in semen, poor quality
Hindlimb lameness from pain
Chronic: hard swelling of tail, testicular degeneration
**Epididymitis: DxCulture from semen (poor morphology), serology (ELISA, CF) (difficult in younger rams)
Epididymitis: txCull older, use oxytetracyclines for younger
Epididymitis: preventionTest & cull B. ovis-positive; raise lambs in extensive conditions
Sperm granuloma: more common in? Cause?Bucks, associated with intersex conditions
Believed to be heritable (recessive)
**Pathogenesis of sperm granulomaAbnormal formation of head of epididymis reulting in blind-ending efferent ductules
Sperm builds up & eventually causes rupture of ductules, resulting in severe inflam condition & granuloma formation (sperm is a FB! blood-testis barrier)
**What else may happen as a result of sperm granuloma?Calcification
Back pressure results in testicular degeneration
Sperm granuloma: CSFirm, often mineralized swelling at head of epididymis, small atrophic testis, progressively infertile
Sperm granuloma: dxUltrasound (mineralization), CS
Sperm granuloma: txNo treatment. cull :(
Gynecomastia aka? what is it?"Milking buck syndrome" (Abnormally enlarged mammary glands) Genetic disorder
Normal libido & fertility but shouldnt be used for breeding
Seen more commonly in high-producing dairy goat lines (Saanen) & polled animals
Polled intersex syndrome: more common in?Dairy (Saanen, Toggenburg, Alpine)
Polled intersex syndrome: are there variations? which one most common?Various phenotypic variations
Male pseudohermaphrodites most common (testes usually internal, look like female goats phenotypically)
How does a polled intersex goat develop?Female-like at birth, start to become larger than other females at puberty & become aggressive towards other goats, develop buck odor & erect neck har. Small teats & enlarged clitoris

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