Swine Theriogenology Flashcards
Gilt
Primparous female
Sow
Multiparous female
Barrow
Castrated male
Boar
Intact male
General facts
Non seasonal polyestrus
- 18-23 day cycle (21 avg)
- gestation length 114 days
- occurs at 6-7 months of age and/or weight of 220-240 pounds (boars attain puberty sooner)
Standing heat will last ______
40-70 hours
- sow seeks male
- displays erect ears and stands perfectly still
- erection after mounting
- mating lasts 5-8 minutes
- large ejaculate (150-200 mls)
Maternal recognition
Conceptus produces estradiol
- estradiol causes PGF2alpha to be rerouted into uterine lumen rather than toward the ovary
- intraluminal PGF does not cause luteolysis
Early pregnancy timeline
All eggs are fertilized
- embryos enter uterus 48 hrs after ovulation
- hatch zona on day 6
- distribute evenly through uterine horns on days 9-11
- implantation begins on day 13
- MRP by day 14
There must be at least _____ viable embryos on day 12 for pregnancy to be maintained
4-5
- required to counteract luteolytic mechanism
Early embryonic death occurs
25-40%
- 20 follicles ovulated, all are fertilized, 40% loss leaves 12 viable fetuses
- most are lost prior to MRP
- others are lost prior to day 40
Pregnancy diagnosis
- boar exposure 18-23 days post breeding
- rectal ultrasound 25-30 days post breeding
- B-mode transabdominal ultrasound at 18-22 days
BSE of boars
Rarely performed, difficult to ID low fertility boars due to heterospermic inseminations
- look at history, PE, libido
- semen collection, gloved hand over dummy
- electroejaculation requires anesthesia
Semen evaluation
Opalescent, milky yellow
- gel free fraction: 150-250 mls
- total sperm: 40 billion
- progressively motile sperm: 70-90%
- morphologically normal sperm: >70%
Female BSE
- rarely performed
- economics
- infertile animals are culled
Puberty induction
Expose gilts older than 150 days to a mature boar twice daily for 30 minutes (whitten effect)
- effective at inducing cyclicity
- vasectomized boars can be used
- injection of PG600
Estrus synchronization
- farm labor better managed
- estrus detection can be intensified
- synchronized farrowings allow for higher survival
- manage gilts, sows, and piglets in groups
Group weaning occurs
21 days postpartum
- > 80% will show estrus in 4-8 days
- easy, cost effective
Progestagens
Artificial corpus luteum
- suppress estrus and cause synchrony upon removal
- good results with altrenogest, with estrus occurring 5-7 days after last feeding
- Matrix
Why are prostaglandins not used?
CL is refractory to PGF until day 12-14
- used to treat a group of animals causing abortion followed by synchronized fertile estrus
When are sows bred
After estrus is first detected and 24 hours later
- gilts are bred at 12 hour intervals
Goal of breeding management
1 litter every 5 months
- 3 months, 3 weeks, 3 days of pregnancy
- 3 weeks of weaning
- 1 week until estrus
Artificial insemination
Boar is collected (sperm rich fraction) twice weekly over a phantom
- diluted with extender (androhep or safecell to store semen up to 10 days)
AI dose
60-100 mls containing 2-3 billion sperm, or 1 billion sperm per day of storage
AI pregnancy rates
- double inseminations can increase preg rates and litter size by 1-2 piglets
- fresh semen can be as good as natural
- preg rates for gils are 10-15% lower than sows
Farrowing
Swelling of vulvar lips beginning 4 days prepartum
- restlessness/nesting behavior starts 24 hrs prior to farrowing
- duration averages 3 hrs but can be 30 min-10 hrs in length
- interpiglet interval is 15-20 min
- fetal membrane expulsion averages 4 hrs but can take up to 12.5 hrs
Advantages to induced farrowing
- labor issues
- survivability, used to reduce pre-weaning mortality
- more attention to piglets, reducing stillborns
- goal is to wean more piglets
Induction of farrowing
Day 112 of gestation give an injection of prostaglandin at 10-11 AM
- sows farrow 20-30 hrs after injection
- 75% respond by next day
- oxytocin to jump start non responders
Why do you remove piglets during farrowing
- prevents crushing
- cannibalism
- colostrum deprivation
Dystocia
Uterine inertia, small pelvic size, inadequate dilation of birth canal
- straining followed by 4 hrs without producing a piglet
- interval between piglets is >1 hrs
- remove piglet by traction if possible
C section
General anesthesia, sedation followed by epidural/local block and restraint
- lateral recumbency, incision is dorsal and parallel to mammary chain (just in front of and below the prefemoral fold)
Cystic ovarian disease
Common cause of irregular cyclicity and anestrus
- diagnosis is presumptive
- no treatment, cull
Zearalenone
Mycotoxin found on corn and barley
- estrogenic effects: vaginal prolapse, vaginitis, abnormal cyclicity, infertility
- dx based on signs and feed analysis
Brucellosis
B. suis
- abortion
- stillborns and birth of weak piglets
- infertility with repeat breeding
- orchitis
- spondylytis with paresis
- card test followed by culture and serology
Brucellosis treatment
No treatment
- reportable disease followed by cull and slaughter
- zoonosis
- control by depopulation
- test young prior to breeding and farrowing
- surveillance
- found in some wild hogs
SMEDI complex
Stillborns Mummies Embryonic Death Infertility
- porcine parvovirus
- porcine reproductive and respiratory syndrome virus
- porcine enterovirus
- pseudorabies
Porcine parvovirus
Gilts and young sows
- embryonic and fetal death, mummification
- abortion is rare
- leads to small litters
- vaccination and controlled infection
- natural infection = lifelong immunity
Porcine enterovirus
Identical symptoms to parvo
- no vaccine
- diagnosis by FA on fetus
- controlled infection
PRRS
Worldwide distribution
- numerous stains
- late term abortions
- premature births and stillbirths
- neonatal death
- respiratory signs in unweaned piglets
- vaccination and controlled infection as for PPV
Pseudorabies
Young pigs it causes nervous signs, diarrhea, vomiting, respiratory distress and rapid death
- SMEDI in adults
- mummies are not common
- late abortions and weak piglets most common
- dx with VI, FA, histopath of fetus
Leptopirosis
Asymptomatic in adults except for stillbirths, weak pigs and late abortions
- persistently shed in urine of infected animals
- edematous icteric fetuses
- dx with MAT, darfield microscopy
- prevent with frequent vaccines, rodent control, water removal
- control outbreak with antibiotics (streptomycin)
Carbon monoxide poisoning
Faulty gas heaters used to heat barns
- abortion/stillbirth in late term sows
- dark coloration of mucous membranes in sows
- dz with history and value of CO >200 ppm
- improve ventilation
- remove/repair faulty heater
