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• What are the two processes involved in growth after fertilization?

  Hiperplasia and hipertrofia
• During which period is growth primarily due to hyperplasia?

  During the initial months after fertilization
• When does most fetal growth occur during pregnancy?

  During the last trimester (day 190 to 282)
• How much does the weight of the fetus increase during the last trimester?

  From 10 to 80 pounds
• What happens to the nutritional requirements of the cow during pregnancy?

  They increase, especially during the last two months of gestation
• What are the stages of development from fertilization to birth?

  • Óvulo
  • Esperma
  • Fertilización
  • Cigoto
  • Mórula
  • Nérula
  • Antes de Nacer
  • Feto Temprano
  • Embrión Tardío
  • Becerro Recién Nacido
• What is the first symptom of pregnancy in cows?

  The absence of estrus (heat)
• What can be presumed if a cow does not return to heat 21 days after insemination?

  She may be pregnant
• Why might a pregnant cow not show signs of heat?

  Due to an ovarian cyst or failure to detect heat
• How long after insemination is a cow generally declared pregnant if no heat is observed?

  At least 60 days
• What percentage of pregnant cows may still show signs of heat?

  About 5%
• What are other signs of pregnancy in heifers?

  Growth of the belly and development of the udder
• How long does gestation last in cows?

  Approximately 283 days
• What is the method for determining pregnancy in cows?

  • Palpación recto vaginal
• What is the definition of parturition?

  The birth of a calf followed by the expulsion of the placenta
• What are the symptoms of impending parturition?

  • Relaxation of pelvic ligaments and muscles
  • Swelling of the vulva
  • Filling of the udder
  • Expulsion of mucus from the vulva
  • Frequent lying down and standing
• What behavioral signs indicate the onset of contractions in cows?

  They kick their belly, stomp with their hind legs, and change positions frequently
• What hormone does the pituitary gland produce during the pre-partum phase?

  Oxitocina
• What is the role of relaxin during parturition?

  It allows the pelvic region to dilate, facilitating birth
• What are the phases of parturition?

  1. Dilatación de la cérvix
  2. Expulsión del feto
  3. Expulsión de la placenta
• How long does the dilation phase last?

  It can vary between 2 and 6 hours
• What happens during the expulsion of the fetus phase?

  It can last from 0.5 to 3 hours, ending with the birth of the calf
• What is the normal time frame for placenta expulsion after birth?

  Normally between 2 to 6 hours
• What is considered retained fetal membranes (RFM)?

  When the placenta is not expelled after 12 hours
• What is necessary for a normal delivery?

  Providing care and monitoring the cow closely
• What should be ensured for a cow during parturition?

  • Close proximity to water
  • Sufficient food
  • Shade if possible
  • Close monitoring without startling the cow
• When should intervention occur during parturition?

  Only in problematic births (dystocic)
• What triggers the parturition process?

  • Stress suffered by the fetus
  • Production of hormones by the fetal hypothalamus
  • Release of ACTH by the fetal pituitary
  • Production of cortisol by the fetal adrenal glands
  • Stimulation of uterine contractions
• What is the role of prostaglandin F2α (PF₂α) in parturition?

  It stimulates luteolysis, decreasing progesterone and increasing estrogen levels
• What happens to the levels of estrogen and oxytocin during parturition?

  They increase, aiding in uterine contractions
• What is the effect of relaxin during parturition?

  It softens and relaxes pelvic ligaments
• What is the significance of the calf's head pressing against the cervix?

  It stimulates a nervous reflex that causes oxytocin secretion
• What is the expected time for the placenta to be expelled after a normal delivery?

  Within 30 minutes to 8 hours
• What is the consequence of not expelling the placenta within 12 hours?

  The cow is considered to have retained fetal membranes (RFM)
• What is the role of the placenta during pregnancy?

  It allows physiological exchange between the fetus and the mother
• What happens if the placenta is expelled normally?

  The delivery is considered normal
• What should be done to ensure a normal delivery?

  Provide necessary care and monitor the cow closely
• What is the importance of monitoring the cow during parturition?

  To ensure she does not experience complications
• What is the role of the hypothalamus in the parturition process?

  It produces and releases the factor that stimulates ACTH production
• What is the cascade of events related to parturition?

  Stress in the fetus leads to hormonal changes that trigger contractions