Hello. I am Shiba Hari Dhakal , undergraduate student of Agriculture science studying 8th semester in Agriculture and Forestry University, Rampur,Nepal. This slide was prepared when I was in Bsc.Ag 5th semester, as an assignment of LPM subject by compiling information from different sources.

1. Estrus Cycle
Prepared by:
Shiba Hari Dhakal
Agriculture and Forestry University

2. • Estrus, also called Oestrus, the period in the sexual cycle of
female mammals, except the higher primates, during which
they are in heat—i.e. ready to accept a male and to mate
• The estrous cycle of the cow starts after puberty and occurs
approx. every 21 days (17 to 24 days) except for pregnancy,
reproductive disease or hormonal disorder
• During estrous cycle, the reproductive tract is prepared for
heat and ovulation

3. • Types of estrus cycle
Polyestrus – Cow, buffalo, swine
Seasonaly polyestrus
a) Long day breeders eg. Mare
b) Short day breeders eg. Sheep and goat
Monoestrus- Dog

4. • Two discrete phases of estrous cycle
The luteal phase (14–18 days; metestrus and diestrus) and
The follicular phase (4–6 days; proestrus and estrus)
• Anestrus- Phase when female does not experience cycle which might
be due to pregnancy, reproductive disease or hormonal disorder
Follicular Phase
Short phase only 20% of cycle
Period from regression of corpus luteum to ovulation
Pre-ovulatory follicle
Dominant hormone is estradiol

5. • Luteal Phase
Long phase about 80% of the cycle
Period from ovulation to corpus luteum regression phase
Corpora lutea phase
Dominant hormone is progesterone
Follicle continue to grow and regress during this phase
The cycle is divided into four parts:
Proestrus
Estrus
Metestrus and
Diestrus

6. • Proestrus
Proestrus is the period between the regression of the corpus luteum
of the previous cycle and estrus
Start when progesterone decline (Luteolysis) and ends at onset of
estrus
Last for 2 to 5 days
FSH and LH are major responsible
Ovarian follicle increase in size
Estrogen absorbed from the follicle into bloodstream and increase
vascularity
Preparation for estrus and pregnancy

7. • Estrus
Estrus is the period when high amount of estrogen is presents in the
blood
The estrogen produces the behavioral signs of estrus
Period of sexual receptivity
Large production of estrogen which stimulate production of LHRH
FSH decrease due to estrogen and inhibin
Ovulation occur due to LH
LH level increase due to LHRH
Estrus stopped due to ovulation

8. Metestrus
Estrus is followed by a 3 to 4 day period referred to as metestrus
During this period the corpus luteum develops under the influence of
LH and starts to produce increasing amounts of progesterone
Corpus luteum predominant
Increase in Progesterone and decrease in estrogen
Diestrus
The period between metestrus and the beginning of the regression of
the corpus luteum is referred to as diestrus
No reproductive activity
Short period
CL is fully functional
High level of progesterone

10. Animal Estrus Cycle
(Days)
Pro-estrus
(Days)
Estrus Metestrus
(Days)
Diestrus
(Days)
Cow 21 3-4 12-18 hour 3-4 10-14
Ewe 17 2-3 24-36 hour 2-3 10-12
Sow 21 3-4 48-72 hour 2-3 11-13
Mare 21 2-3 4-8 days 2-3 10-12

11. OVULATION

13. • The process in which an oocyte (female germ cell) is released from
the Graafian follicle
• Ovulation occurs at the ovary surface
• Ovulation is triggered by the surge of LH surge from the pituitary
• Multiple ovulation
• FSH stimulate the growth of ovarian follicles by which one or more
follicle grow rapidly
• LH help to shedding of the egg and growth of luteal tissue to form CL
• After the rise of LH level and stimulate ovulation
Fertilization is union of sperm and ovum but when ova is not fertilized
it degenerate within few days

14. • In the natural sequence of mammalian fertilization, the spermatozoa await the
arrival of ova in the Fallopian tubes. The time of waiting may vary from 6 hr. (rabbit),
20–30 hr. (pig, sheep and cattle) up to perhaps several months (bat)
• Cumulus cell is found
• Acrosomal enzymes is responsible for penetration
Gestation period
period from the time of conception until birth
Gestation length of Cow- 283 days (279-287)
Buffalo- 281-334
Sheep-144-152
Goat -148-152
Horse-330-342
Pig -112-120
Donkey – approx. 365
Poultry – 18-21 days incubation period

15. • Factor affecting gestation length
Age- more age more gestation length. Culling is necessary
Sex – male have more GL
Birth weight – More weight more gestation length
Breed- Jersey have more than Holstein
Birth type- multiple birth have short than single birth

16. Thank You