4 Stages of estrus cycle in Cows

Stages of estrus cycle in Cows

Following the onset of puberty in domestic animals there is the development of a physiologic rhythm of the reproductive system called the “Estrous cycle”.
The estrous cycle of the domestic animals is divided into Four phases or periods which blend one into the other.
Estrus cycle (4 stages)

  • These phases are;
  • Proestrus– Also known as building a period and begins with luteal regression and end with onset of estrus.- Duration is 2-5 Days.
    – There is follicular growth and regression of CL of previous cycle (in polycyclic species).
    – Uterus enlarge very slightly.
  • Estrus– Endometrium is congested and oedematous- Vaginal mucosa become hyperemic.
    – The bitch show external evidence of proestrus with vulval odema and sanguineous vulval discharge.
    – The period of acceptance of male.
    – The uterine , cervical  and vaginal glands secrete increased amount of mucus.
    – The vaginal Epithelium and Endometrium become hyperaemic Metestrus congested.
    – The cervix is relaxed.
    – Ovulation occur during this phase of cycling all domestic species exept in cow where it occurs about 12 Hours after the end of estrus.
    – Ovulation is the spontaneous process in all domestic species except in cat , rabbit and camel in which it is induced by the act of coitus.
    – During pro-estrus and estrus there is follicular growth in absence of CL  and  main hormone is estrogen .
  • Metestrus- Metestrus is the period from ovulation & formation of CL.- It is ill defined phase.
    – The granulosa cell of the ovulated follicle rise to luteal cells which is responsible for formation of CL called as luteinization.
    – There is a reduction in cervical, vagina and uterine secretion.
    – Post oestrus or metestrus bleeding occurs.
    – Cervix is relaxed.
  • Diestrus- Longest phase of oestrus cycle.- Fully functional Corpus Luteum.
    – High level of progesterone.
    – Female do not exhibit sexual receptivity.
    – The uterine gland undergo hyperplasia and hypertrophy
    – Vaginal mucosa become pale.
    – Cervix is constricted.
    – Thickening of endometrium.
    – Vaginal, uterine and cervical secretion is decreases.

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