Stages of reproduction
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Stages of Reproduction. Principles of Agricultural Science – Animal. Unit 6 – Lesson 6.3 The Pathway to Production. Puberty. The time when sexual maturity is reached Influenced mostly by age and weight In males, sperm production begins In females, estrous cycle begins. Estrous Cycle.

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Stages of Reproduction

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Stages of reproduction

Stages of Reproduction

Principles of Agricultural Science – Animal

Unit 6 – Lesson 6.3 The Pathway to Production


Puberty

Puberty

  • The time when sexual maturity is reached

  • Influenced mostly by age and weight

  • In males, sperm production begins

  • In females, estrous cycle begins


Estrous cycle

Estrous Cycle

  • The reproductive cycle in females in preparation for pregnancy

  • Controlled by hormones

  • Length is dependent on species


Types of estrous cycles

Types of Estrous Cycles

  • Polyestrous – several estrous cycles in a year (e.g., cats, cows and pigs)

  • Seasonally polyestrous – more than one estrous cycle during a specific time of the year:

    • Short-day breeders – fall or winter (e.g., sheep and goats)

    • Long-day breeders – spring and summer (e.g., horses)


Types of estrous cycles1

Types of Estrous Cycles

  • Diestrous – heat twice per year (e.g., dogs)

  • Other - constant estrus, able to conceive at almost any moment (rabbits)


Estrus

Estrus

  • Period of time when the female is receptive to the male

    • Also called heat

  • Estrogen level is high, progesterone level is low

  • Signs of estrus in females:

    • Nervousness

    • Swelling of the vulva

    • Frequent urination


Estrous vs menstrual cycle

Estrous vs. Menstrual Cycle

  • Hormonal control is similar in both

  • Estrous Cycle

    • Endometrium is reabsorbed

    • Only sexually receptive when in heat

  • Menstrual Cycle

    • Endometrium is expelled

    • Sexually active at any time in cycle


Gestation

Gestation

  • The length of time from conception to birth of young

  • Also known as pregnancy

  • Length varies greatly among species

  • Fetus develops in uterus or uterine horn


Parturition

Parturition

  • The act of giving birth

  • Initiated by hormones released from fetus

  • Signs of parturition:

    • Restlessness

    • Swelling of vulva and udder

    • Uterine contractions


Lactation

Lactation

  • The period of milk secretion

  • Begins at parturition and ends at weaning

  • Exception – dairy cattle

    • Lactation period extends until the cow is dried off prior to calving


Hormones

Hormones

  • http://www.youtube.com/watch?v=WGJsrGmWeKE


References

References

Taylor, R. & Field, T. (2007). Scientific farm animal production: An introduction to animal science (7th ed.) Upper Saddle River, NJ: Prentice Hall.

Lawhead, J., & Baker, M. (2005). Introduction to veterinary science. Clifton Park, NY: Delmar.

Damron, W.E. (2000). Introduction to animal science: Global, biological, social, and industry perspectives. Upper Saddle River, NJ: Prentice Hall, Inc.


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