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Gestation and Parturition

Gestation and Parturition. Gestation. Length of PREGNANCY. Begins with FERTILIZATION and ends with PARTURITION (BIRTH). All animals have DIFFERENT gestation lengths. Usually the LARGER the animal, the LONGER the gestation length. Gestation period Length -Cattle.

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Gestation and Parturition

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  1. Gestation and Parturition

  2. Gestation • Length of PREGNANCY. • Begins with FERTILIZATION and ends with PARTURITION (BIRTH). • All animals have DIFFERENT gestation lengths. Usually the LARGER the animal, the LONGER the gestation length.

  3. Gestation period Length -Cattle • Range 274-294 days • Average 283 days

  4. Gestation period Length - Sheep • Range 144-152 days • Average 148 days

  5. Gestation period Length - Swine • Range 110-118 days • Average 115 days

  6. Gestation period Length - Horses • Range 310-370 days • Average 336 days

  7. Gestation period Length - Rabbit • Range 30-31 days • Average 30 days

  8. Gestation period Length - Goat • Range 144-154 days • Average 149 days

  9. Gestation period Length - Chicken • Range 19-22 days • Average 21 days

  10. Gestation period length • The length of gestation is GENETICALLY determined, but other factors cause it to VARY, such as: a. Maternal Factors -- age of the dam (mother) b. Fetal Factors -- litter size, sex of fetus

  11. Gestation period length • The length of gestation is GENETICALLY determined, but other factors cause it to VARY, such as: c. Genetic Factors -- species, breed, fetal genotype d. Environmental Factors -- nutrition, temperature, season

  12. Gestation period length • Knowledge of the length of gestation period is important to the producer because: a. it helps to regulate production cycles b. it helps in the planning of the breeding program c. it helps to predict the date of birth

  13. Abortion - • EXPULSION of the fetus before the time of PARTURITION.

  14. Causes for abortions: • 1. Infections a. Bacteria and Fungi (ex., Brucellosis [Bangs], Vibriosis) b. Viral (ex., Bovine Virus Diarrhea [BVD]) c. Protozoans (ex., Trichomoniasis)

  15. Causes for abortions: • 2. Genetic Abortions a. Occur when the fetus is malformed b. Dam's body usually rejects the malformed fetus for reasons unknown.

  16. Causes for abortions: • 3. Injury related abortions a. Rare because fetus is well protected b. Prevent injuries caused by kicking, bumping, or squeezing

  17. Causes for abortions: • 4. Nutrition Examples: - Poisonous Plants - Ration too low in required nutrients

  18. Development • 3 periods of development from pregnancy to birth - Ovum Period - Embryonic Period - Fetal Period

  19. Ovum Period ( Days 0 to 15 in cattle) • 1. Fertilization - the union of the egg and sperm nuclei – takes place in fallopian tube

  20. Ovum Period • 2. Cell Division- after the cell has been fertilized it begins to divide (Mitosis) 1 becomes 2 becomes 4 becomes 8, 16, 32, 64, . . .

  21. Stages during the ovum period • Zygote – 2 to 8 cells

  22. Stages during the ovum period • A. Zygote – 2 to 8 cells • B. Morula – spherical mass of cells (outer layer and central core)

  23. Stages during the ovum period • A. Zygote – 2 to 8 cells • B. Morula – spherical mass of cells (outer layer and central core) • C. Blastula -- mass of cells with a hollow cavity

  24. Embryo Period (Days 16 to 45 in cattle) • 3. Implantation - the new embryo becomes implanted in the uterine horn where it will be nourished and develop.

  25. Abnormal implantation • Ovarian: Young seldom survive to full term • Tubal: Young occasionally survive to birth • Abdominal: Young do not survive to full term

  26. Embryo Period • 4. Differentiation - cells become organized into specific structures

  27. Three layers of development tissue: • a. Ectoderm - the outside layer that becomes the skin and nervous system • b. Mesoderm - the middle layer that becomes the bones and muscles • c. Endoderm- the inside layer that becomes the lungs and digestive system

  28. Embryo Period • 5. Completion of all major ORGAN systems.

  29. Embryo Period • 6. Looks like the ORGANISM.

  30. Fetal Period (Days 46 to 283 in cattle) • 7. Placentation - MEMBRANES develop to provide the FETUS with NUTRITION. • Each embryo usually has their own set of membranes (Twins in cattle have common membranes and common blood supply [Freemartin])

  31. Placental Structures: • Amnion – inner most layer that forms a sac around the embryo/fetus. (Amniotic Sac) • Filled with amniotic fluid that protects young from shock and adhesion

  32. Placental Structures: • Allantois – middle layer that also forms a sac • Filled with allantoic fluid that accumulates waste from the developing fetus • Chorion – outer layer that attaches to the uterus

  33. Cow Ewe Types of placental attachment • Cotyledon – contacts made only at certain points in the uterus • Also known as “buttons” • Cows and Ewes

  34. Types of placental attachment • Diffuse – contact is made over most of the uterus • Mares, sows, humans

  35. Placental Structures • Umbilical Cord - long FLEXIBLE tube attached to the placenta where FOOD, OXYGEN, and WASTES are exchanged between the MOTHER and the baby.

  36. Placental Barrier • Placenta prevents large molecules from passing from mother to young. • Viruses are small enough to penetrate as are certain other chemicals.

  37. Fetal Period • 8. Growth and Development - the fetus GROWS and organs continue to DEVELOP so that the animal can LIVE on its OWN.

  38. Parturition -the act of giving birth

  39. Signs of birth in cattle 1. Swollen udder 2. Fluid in udder changes from watery to thick, milky colostrum 3. Muscles around tailhead shrink

  40. Signs of birth in cattle 4. Noticeable enlargement and swelling of the vulva 5. Cow is nervous, uneasy, anorexic

  41. Signs of birth in cattle 6. Muscular contractions start 7. Look for young 8. Makes a nest or seeks out an isolated area

  42. Signs of birth in sheep 1. 10 days prior, ewe teats become firm and full of milk 2. Vulva swollen 3. Cervical seal passes as thick creamy mucus 4. Ewe becomes nervous (switches from laying to standing)

  43. Signs of birth in horses 1. 2-6 weeks prior, udder swells 2. 7-10 days prior, muscles shrink and abdomen drops 3. 4-6 days prior, teats fill with milk 4. 12-24 hours prior, “wax” appears on nipples (“waxing”)

  44. Signs of birth in pigs 1. About 3 days prior, sow will spend most of time sleeping and feeding 2. As labor draws nearer, sow begins “nest building”

  45. Signs of birth in pigs 3. Will clean and dry birth site (will chew long grass or straw to provide bedding) 4. Vulva enlarges 5. 10-18 hours before farrowing, milk fills the teats

  46. Stages of Parturition (Labor) • Stage 1 - Preparatory Stage • Stage 2 - Expulsion of fetus • Stage 3 - Expulsion of the placenta • Stage 4 - Period of Rest

  47. Preparatory Stage 1. Restlessness of animal due to minor contractions 2. Dilation of the cervix 3. Cervix expands allowing uterus and vagina to become a continuous canal

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