Reproductive Biology in Mammals

Mammalian Reproduction

• Ova in mammals are fertilized in the oviduct, also known as Fallopian Tubes.

Cotyledonary Placentas

• Cotyledons are the fetal side, and caruncles are the maternal side.
• Together, they form the placentome.

Placentation in Specific Animals

• Primates, humans, and rabbits have a hemochorial and discoid placentation.

Canine Reproduction

• Increase in estrogens speeds up turnover of vaginal epithelial cells, causing progressive cornification.
• Cell color changes:
  • Anestrus and proestrus: pink-purple
  • Estrus and diestrus: blue-purple
• Parturition occurs 58-72 days after breeding at an unknown stage of estrus.
• Basenji: one estrous cycle per year.
• Diagnosis methods:
  • Radiographs: count litter size after 45 days
  • Abdominal palpation: detect pregnancy at about 21 days
• Impending parturition can be predicted by a transient temperature drop in the bitch.
• LH surge peaks at behavioral estrus and acceptance of male, ovulation occurs 2 days later.

Feline Reproduction

• Birth occurs 64-69 days from breeding at an unknown state of estrus or 63 days from breeding at ovulation.
• Diagnosis methods:
  • Abdominal palpation: reliably detects pregnancy at about 21 days
  • Ultrasound: detects fetal heartbeat at 28 days
  • Radiographs: count litter size after 40 days
• Obvious mammary development can be seen in the final 2 weeks.
• Estrus cycle recurs every 2-3 weeks (interestrus interval).

Bovine Reproduction

• Estrus behavior lasts 18 hours.
• Signs of estrus:
  • Standing to be mounted
  • Riding other cows
  • Restlessness
  • Bellowing
  • Ruffled hair or hair loss on tail head
• Clear vaginal mucus discharge appears after estrus.
• During diestrus, a cow has a soft corpus luteum.
• Diagnosis methods:
  • Placentomes can be felt at 70-75 days
  • Membrane slip can be felt at 30-35 days
  • Fremitus can be felt at 90-120 days
• Freemartins:
  • Sterile female calves born twin to a male
  • Underdeveloped ovaries due to XY antigens crossing the chorionic placenta blood vessels
  • Characterized by a short vagina and no cervix

Bovine Reproductive Management

• Estrus detection rates: approximately 50-65%.
• Calving interval: around 13 months.
• First service conception rate: 40% or greater.
• Average days open: around 115 days, ideally in the low 100s.
• Services per conception:
  • Pregnant cows: less than 2.5
  • All cows serviced: less than 3.5
• Number of cows in estrus on a given day:
  • Divide the number of non-pregnant cows by 18 and then by 21.

This quiz covers the fertilization process in mammals, including the structure and function of placentation in different species, and the reproductive cycles of dogs.