URO - Week 1/2

Question 1

Define Oestrus cycle

Answer 1

a repetitive pattern of hormones and behaviours which lead to the ovulation of a follicle

Question 2

State the 4 phases of the oestrus cycle

Answer 2

pro oestrus
oestrus
met oestrus
dioestrus

Question 3

When do we enter dioestrus from met oestrus?

Answer 3

when the corpus luteum has fully matured

Question 4

State general oestrus female behaviour patterns
- why is this?

Answer 4

receptive to male = lordosis
due to high concentration of oestradiol

Question 5

state general dioestrus female behaviour patterns
- why is this?

Answer 5

rejects the male
due to high concentration of progesterone

Question 6

State 2 steroid hormones involved in the oestrus cycle

Answer 6

oestradiol
progesterone

Question 7

state 2 gonadotrophin hormones involved in the oestrus cycle

Answer 7

follicle stimulating hormone
luteinising hormone

Question 8

how can you group the 4 phases of the oestrus cycle into 2?

Answer 8

pro oestrus and oestrus are the follicular phase
met oestrus and dioestrus are the luteal phase

Question 9

What happens during the follicular phase? 3

Answer 9

the ovarian follicles mature
the maturing follicles secrete increasing concentrations of oestradiol into the blood
this brings about oestrus behaviours

Question 10

What happens during the luteal phase? 4

Answer 10

the remains of the ovulated follicle become the corpus luteum
the corpus luteum secretes progesterone
the corpus luteum undergoes luteolysis by prostaglandin f2 alpha
follicles are continually developing but fail to ovulate during this phase

Question 11

After ovulation, where does the oocyte go?

Answer 11

into the oviduct

Question 12

Define polyoestrus

Answer 12

multiple cycles throughout the year

Question 13

what does it mean to be seasonally polyoestrus?
- what 2 types are there?
- give examples of animals for each

Answer 13

to have multiple cycles throughout one season

long day
mare and queen

short day
ewe

Question 14

what does monoestrus mean?

Answer 14

infrequent cycles independent of the season

Question 15

Seasonal Polyoestrus: Why are some animals seasonally polyoestrus? 2

Answer 15

it ensures birth at a suitable time of year for best weather and nutrition
so the offspring have the optimum chance of survival

Question 16

State the length of the oestrus cycle for a queen
- what about length of oestrus?
- What type of ovulator are cats?

Answer 16

21 days

7-10 days

induced ovulator

Question 17

When do Jills (female ferret) ovulate?
- How long is their oestrus cycle?
- Why is it so important they are either mated or spayed?

Answer 17

induced ovulator and ovulate 30-40 hours after mating

14 days if mated and 6 months if not mated

because their oestradiol will remain elevated unless mated which has health implications

Question 18

Bitch: How long is the period of an an oestrus after a cycle?
- How long is the period of time between oestruses? (inter-oestrus period)

Answer 18

3 months

7 months

Question 19

Give one method of removing the need for oestrus detection in cows
- What does it consist of?

Answer 19

ovsynch

GnRH and prostaglandin F2 alpha

Question 20

Queen: How long is Pro-oestrus?
- How does it work with ‘induced ovulation’?
- Why is it important to detect oestrus?

Answer 20

very short and often unnoticed

there is an LH surge in response to mating

because the LH response to mating decreases with each day of oestrus and follicles ultimately regress

Question 21

Queen: Describe some behavioural signs of oestrus 7

Answer 21

increased vocalisation
rubbing and rolling
increased activity and seeking tom
slight mucoid vulval discharge
extending hindlimbs
tail erect and held to one side
stands to be mated and lowered on front quarters

Question 22

Anoestrus: When does Anoestrus occur physiologically ? 4

Answer 22

during lactation
in the presence of offspring for some species
for seasonal polyoestrus species
for monstrous breeders

Question 23

Anoestrus: When can it occur pathologically? 2

Answer 23

metabolic or heat stress
ovarian pathologies

Question 24

Silent oestrus: What is this?

Answer 24

ovulation with limited signs of oestrus

Question 25

Silent oestrus: When can it occur?

Answer 25

typically occurs the first oestrus after seasonal an oestrus or parturition

Question 26

Silent oestrus: Why does it occur? 3

Answer 26

no progesterone priming on brain centres
no progesterone fall to trigger oestradiol receptor expression in brain
no sudden release of oestradiol

Question 27

Silent oestrus: In dairy cows, when does it occur? 2
- Why can prolongs silent oestrus be a problem?
- What are the possible solutions? 2

Answer 27

it occurs at the first ovulation after parturition
can occur in subsequent cycles

missed opportunities for breeding

ovsynch
profiling progesterone levels in milk

Question 28

Bitch: Why are they monoestrus?
- What about the timing of their ovulation?

Answer 28

they have a 7 month gap between oestrus

they are spontaneous ovulators

Question 29

Bitch: How does their oestrus cycle compare to other species? 5

Answer 29

longer follicular phase
longer luteal phase
long period of anoestus after luteal phase
pre-ovulatory luteinisation
oocyte is ovulated less mature than in other species

Question 30

Bitch: What causes the pre-ovulatory rise in progesterone conc?
- explain what happens

Answer 30

pre-ovulatory luteinisation

production of luteal cells in the wall of the follicle producing progesterone

Question 31

Bitch: Describe the differences between a progesterone profile of a pregnant vs non-pregnant bitch

Answer 31

progesterone concentration is slightly greater in the pregnant dog from day 21
rapid fall in progesterone at parturition which doesn’t occur in the non-pregnant bitch

Question 32

Bitch: Is prolactin produced only in pregnant bitches?

Answer 32

no it is secreted in the non-pregnant bitch too