Farm Animal Reproduction


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Farm Animal Reproduction

  1. 1.  Consists of proestrus, estrus, metestrus, diestrus and anestrus1. proestrus- begins after corpus luteumregression, ends at the onset of estrus. During thisperiod there is rapid development of the folliclewhich leads to ovulation and the onset of sexualreceptivity
  2. 2. 2. estrus- time of sexual receptivity, may bereferred to as heat. Ovulation usually, but notalways, occurs at the end of estrus. - Some species, like cats and ferrets, are induced ovulators3. metestrus- the early postovulatory periodduring which the corpus luteum beginsdevelopment
  3. 3. 4. diestrus- the period of mature luteal activitywhich begins about 4 days after ovulation endends with regression of the corpus lutem.5. Anestrus- without estrus cycles
  4. 4.  Hypothalamus- Located in center of brain, next to pituitary gland. Considered a master gland that controls the pituitary gland- Releases FSHRH ( follicle stimulating hormone releasing hormone) which acts on the anterior pituitary
  5. 5.  Anterior pituitary- In response to FSHRH releases FSH ( follicle stimulating hormone)- FSH acts on the ovary
  6. 6.  Ovary- In response to FSH it begins to develop a follicle- Follicle is like a small blister on the ovary and contains a maturing egg- Follicle produces estrogen which causes the animal to come in heat ( estrus)- Estrus in cows is about 18 hours
  7. 7.  Hypothalamus- Produces GNRH gonadotropin releasing hormone when estrogen has been present for a sufficient amount of time- Causes the anterior pituitary to release leutenizing hormone ( LH)
  8. 8.  Anterior pituitary- Releases LH in response to GNRH- LH causes the follicle to rupture leading to ovulation
  9. 9.  Ovary- Rupturing of the follicle occurs with low estrogen and high leutenizing hormone- Egg released into the oviduct ( occurs 12-24 horus after estrus in cow)- Menstrual bleeding may occur but not in every estrus- Corpus luteum is formed out of the remaining follicle- Most successful artificial insemination is done 12 hours after the beginning of estrus ( so insemination precedes ovulation)
  10. 10.  Corpus luteum- Yellow body made up of remaining follicle tissue- Formation is initiated by the LH surge- Produces progesterone which maintains the lining of the uterus for possible implantation- If implantation occurs the placenta in the cow will continue to produce progesterone to maintain the pregnancy until birth
  11. 11.  Not pregnant- The corpus luteum only lasts about 3 weeks so if implantation does not occur, the lining of the uterus will be sloughed and replaced- The uterus will produce prostaglandins if not pregnant ( help the uterus to contract)
  12. 12.  Ovary ( if not pregnant)- The prostaglandins produced by the uterus if not pregnant ( 14 days after ovulation) will travel to the ovary and cause lutealysis- The corpus luteum will be destroyed which will drop the progesterone level- The dropping of the progesterone level will let the animal come back into estrus
  13. 13.  Pregnant animal- First the corpus luteum secretes progesterone and continues to do so throughout most of the pregnancy- Then the placenta takes over to maintain pregnancy- Implantation takes 5 weeks in cattle and horses
  14. 14.  Diffuse placenta- in horse and pig Cotyledonary placenta – in ruminants Zonary placenta- in dogs and cats Discoid placenta- in humans and monkeys
  15. 15.  Follicle stimulating hormone ( FSH) – follicle development/maturation Luteinizing hormone (LH)- ovulation Estrogen- behavioral signs of estrus, psychic heat, attracting male, accepting male Progesterone- prevents ovulation/maintains pregnancy Oxytocin- uterine contractions, milk letdown
  16. 16.  Bovine- Polyestrus all year long- Beef cattle spring calving, minimizes labor costs- Dairy cattle, year round calving for milk production
  17. 17.  Equine- Seasonally polyestrus in spring and summer- Ovarian activity increases with increased day length- Ovarian activity can be induced/manipulated with artifical lighting Porcine- polyestrus all year long Ovine/caprine- polyestrus fall/winter
  18. 18.  Vaginal discharge, blood tinged or otherwise is not associated with estrus 14-28 day estrous cycle with 21 days being the average Length of estrus ranges from 6-24 hours with the average being 15 hours Time of ovulation is 24-32 hours after onset of estrus
  19. 19.  Proestrus cows will mount estrus cows Gomer bulls ( penis surgically redirected out of lateral aspect of prepuce to prevent breeding) will detect females in estrus
  20. 20.  Prostaglanding F2 alpha- lyses corpus luteum to bring animal into estrus Progestogen ( regumate) synthetic progesterone- suppresses ovaries, prevents estrus, aids in pregnancy maintenance Human chorionic gonadotropin, comparable to LH to induce ovulation Oxytocin- induce labor Dexamethasone- induction of labor Artificial light- alteration of day length
  21. 21.  Natural cover- Male and female must be present and capable of breeding- Limits potential progeny- Risk of physical injury to male or female Pasture breeding Hand breeding
  22. 22.  Increased breedings per ejaculate Semen extender used Disease control Trained personel required Males do not need to be maintained on farm
  23. 23.  Allows multiple pregnancies per breeding season Successful reproduction of physically compromised animals Donor female can still compete Recipient dam just carries the baby, shares no genetic material with fetus Used to create number of genetically similar individuals
  24. 24.  Estrus synchronization of donor and recipients Superovulation of donor by FSH administration 40 hours prior to estrus Insemination hand breeding or artificial insemination Embryo collection established post insemination
  25. 25.  Balloon catheter established proximal to cervix 1-2 liters of buffered saline infused into cervix Gravity used to recover saline and embryos Embryos caught by in line filter Embryo evaluation/processing Embryo delivery to recipient dam
  26. 26.  Overall physical condition Breeding history Semen analysis Semen collection Scrotal circumference Libido/reproductive behavior
  27. 27.  Overall physical condition Breeding history Rectal palpation Ultrasound Uterine culture Uterine biopsy Endoscopic exam of uterus Serum hormone assays
  28. 28.  Failure to return to estrus Rectal palpation early in cow by palpating a CL or enlarged uterine horn at 30-45 days Doppler Ultrasound, transrectal ultrasound Progesterone levels in blood and milk At 3 months, increase in blood flow in uterine artery is felt as a buzz Ballottment- pressure on lower right abdominal wall with fist or knee and lifts fetus, feel it kick back into place
  29. 29.  Early pregnancy diagnosis 14-15 days Twin reduction <18 days Fetal sex determination 65 days Gestation period in bovine is 280-290 days with some breed variation
  30. 30.  Signs of impending parturition- Relaxation of tail head muscles- Relaxing /Lengthening of vulva- Waxing of teats- yellow tinged colostrum, extended/excessive dripping may result in insufficient colostrum available for newborn
  31. 31. Stage 1 labor- may be interrupted several timeswithout injury to fetusStage 2- duration one hour - Rupture of placental membranes, water breaking, may look like urination - Vaginal exam is performed 5-10 minutes after onset of stage 2 labor to assess fetal presentation, cervical dilationStage 3- placenta delivered
  32. 32.  Presentation of fetus- forelegs first ( breech birth, hindlegs first, is normal presentation in goats, swine and sheep) Most cows and mares will lie down prior to expelling calf/foal, if traction is required for delivery, attendant pulls down- toward the dams hocks, not straight out, parallel with the spine
  33. 33.  Allow neonate to rest with hindlegs still in vaginal canal if the umbilical cord is intact. Up to 1 liter of blood may be transferred from the placenta to offspring Neonate should be standing, ambulatory and nursing within one hour after birth Expulsion of placental/fetal membranes ( afterbirth) cleaning should occur within several hours of birth. Membranes that are not completely passed within 8-12 hours represent a medical emergency; retained placenta
  34. 34.  Factors affecting risk of dystocia- Abnormal presentation- Multiple births- Heifer vs cow- Pelvic measurement- Nutritional status- obesity/malnutrition
  35. 35.  Repulsion then traction Pubic symphysiotomy- in first calf heifers, if calfs head is larger than the pelvic canal the veterinarian can open and spread the suture between the pubic bones thus enlarging the pelvic canal diameter Cesarean section Fetotomy- if fetus is dead, dismembered and delivered in pieces. Note: care must be taken to avoid sharp bone pieces piercing/rupturing uterine wall
  36. 36.  Examine vagina, vulva and perineal body for injury Examine afterbirth for completeness Examine mammary glands, express colostrum for evaluation Monitor abdominal discomfort, mm Monitor maternal behavior, interaction with newborn
  37. 37.  Vaginal/uterine prolapse Obturator paralysis Milk fever/hypocalcemic tetany Rejection of offspring
  38. 38.  Colostrum- Requirement – 1 liter per 100 lbs- Colostrum banking- dams will produce more colostrum than needed. After neonate has consumed a sufficient amount, the rest may be milked out and frozen for storage for up to 1 year
  39. 39. - Colostrum quality- ( quality = immunoglobulin content)a. subjective- stickiness, thickness (Note: color is not a reliable criteria for assessing quality)b. Objective- specific gravity > 1.060- Gut closure- the neonatal intestinal tract has thetransient capability to absorb large (immunoglobulins) molecules intact. Thatcapability is lost after 24 hours or the consumptionof 32 ounces of material. Colostrum consumedafter gut closure is of no benefit.
  40. 40. - behavior- strong suck reflex- Umbilicus- iodine ( foals apply every 12 hours until navel remains dry)- Meconium- feces that accumulates in the colon during fetal development, can be rock hard and difficult to pass. If straining is observed, administer phosphate enemas until meconium is passed. ( colostrum has laxative)
  41. 41.  Distress, lack of vigor, cyanosis  Aspiration of amniotic fluid- breech birth/dystocia- hold foal/calf upside down to clear airway of fluid before initiating CPRa. A- airway, establish patent airway firstb. B- breathing, dopram may be administered to stimulate respirationc. C circulation- cardiac compressions, resuscitation
  42. 42.  Failure of Passive Transfer- absence or decreased levels of circulating IgG ( of maternal origin, neonate cannot produce its own IgG until 3-4 months of age)a. IgG <200 mg/dl is complete failureb. IgG200-400 mg/dl- is partial failurec. IgG > 400 is adequate passive transfer
  43. 43.  Mare origin failure of passive transfer- Loss prior to foaling ( leaking)- Poor quality ( low levels of immunoglobulins in colostrum)- Failure to produce colostrum, neonates born before reaching term
  44. 44.  Foal origin failure of passive transfer- Inadequate colostrum- Gut closure Treatment- Administer colostrum or plasma orally if FPT is diagnosed before gut closure- Administer plasma intravenously if FPT is diagnosed after gut closure
  45. 45.  Maternal antibodies in colostrum destroy foals RBC’s- Does not occur in primiparous, first foal mares- Symptoms: anemia, icterus, hemoglobinuria- Prevention: agglutination test prior to allowing foal to nurse- Agglutination test- foals RBC’s mixed with graded dilutions of colostrum, evaluated for agglutination- TX: transfusion if HCT < 15%
  46. 46.  Dummy foal syndrome Suck reflex absent and may take 30+ days to resolve High risk foal-failure of passive transfer or neonatal septicemia Guarded prognosis
  47. 47.  Neonate should consume 10% of body weight per day in milk or milk replacer Foals: typical nursing pattern of once per hour consuming 90 ml per feeding Note: mare goes into heat 5-7 days post foaling. Hormones passed in milk result in diarrhea of foal ( foal heat diarrhea). This diarrhea rarely requires medical intervention and spontaneously resolves when mare goes out of heat.
  48. 48.  Orphan animal/animals unable to nurse on dama. Bottle feeding- healthy animals with normalsuck reflexb. Bucket feeding - Much easier than bottle feeding - Orphans should be trained to bucket asap to minimize labor costs and decrease aberrant behavior associated with hand raised animals
  49. 49. - Tube feeding for foals lacking sucking reflex- Esophageal feeder for calves/lambs/kids- Transfer of neonate to foster dam
  50. 50.  Deworming- typically begins at the same time as initial vaccination series Vaccinations not performed until maternal antibody levels decrease- Foals: 4 months- Calves: 6 months- Sheep/goats- 2 months- Pigs- 3 weeks
  51. 51.  Social behavior1. Imprinting - Training to accept procedures that will be performed later in life - Bonding with dam/other animals/humans2. Provide companion if dam is unavailable,alternate species is acceptable