Intro to farm animal repro

Question 1

What is the most useful landmark when palpating repro tract

Answer 1

cervix

Question 2

What does a follicle secrete

Answer 2

oestradiol- drives oestrus

Question 3

what does a corpus luteum produce

Answer 3

progesterone

Question 4

what is corpus luteum

Answer 4

highly vascularised, transient endocrine gland

Question 5

what do a CL look like on Ultrasound

Answer 5

homogenous medium echogenicity

Question 6

When does ovulation occur in the cow

Answer 6

12hrs after end of oestrus

Question 7

If a CL is 20 mm what does this mean

Answer 7

CL is either growing or regressing

Question 8

How long is the duration of oestrus in the cow

Answer 8

5-18hrs
will ovulate 12hrs after end of oestrus

Question 9

How long is the oestrus cycle in the cow

Answer 9

21-22 days

Question 10

How long is the oestrus cycle in the ewe

Answer 10

17 days

Question 11

How long is oestrus in the ewe

Answer 11

24-36 hrs
ovulate 30-36 hours from begging of oestrus

Question 12

How long is the oestrus cycle in the sow

Answer 12

21 days

Question 13

how long is oestrus in the sow

Answer 13

48-72hrs
ovulate 35-45 hours from beggining of oestrus

Question 14

What is the main oestrus detection method in the sow

Answer 14

back pressure test

Question 15

Describe the resumption of full ovarian activity after parturition

Answer 15

At parturition, pituitary isrefractory to GnRH, but
FSH secretion initiated due to lack of negative feedback, this leads to emergence of an antral follicular wave
Increasing sensitivity of gonadotropes to GnRH, leading to
Increased FSH-stimulation of oestradiol production
Increased LH pulse frequency
Ovulation, often accompanied by silent oestrus

Question 16

List 3 causes of physiological anoestrus

Answer 16

gestation
lactation/ presence of offspring
seasonality

Question 17

List 2 causes of pathologuical anoestrus

Answer 17

stress- metabolic or heat
ovarian pathologies - Cystic ovarian disorders or Inactive ovarian activity

Question 18

How does suckling cause anoestrus in the sow

Answer 18

Early follicular activity but
Prolactin suppresses LH secretion, thus no ovulation

Question 19

Deescribe how sows return to oestrus

Answer 19

Weaning ‘initiates’ oestrus and LH surge within 7 days (WOI)
Weaning to oestrus interval (WOI) is affected by length of lactation / timing of weaning

Question 20

what does giving synthetic GnRH do

Answer 20

Hastens impending cyclicity/ return to oestrus
Hastens ovulation by inducing LH surge. - if dominant follicle there
“Force” ovulation/luteinisation of cystic structures

Question 21

what does giving synthetic FSH do

Answer 21

Stimulates antral follicular growth- results in multiple dominant follicles- embryo transfer

Question 22

How is synthetic progesterones used

Answer 22

Progesterone has a negative feedback effect upon the hypothalamus and anterior pituitary
Suppress the hypothalamic-gonadal axis thus:
Used as method of inducing/synchronising oestrus following withdrawal of the product

Question 23

what does prostaglandin F2a do

Answer 23

Lysis of the mature CL, causing progesterone to decline
Smooth muscle contraction i.e. ecbolic effect on uterus

Question 24

After administration of PGF2a when will the cow come into oestrus

Answer 24

3-4 days after PGF2a administration- if there is a mature follicle

Question 25

Why can’t we use 2 doses of PGF2a in sows

Answer 25

Cl only responsive day 11-16

Question 26

List 3 ways to stimulate onset of early cyclicity in sheep

Answer 26

Melatonin
Progestogen sponges in combination with eCG/GnRH
Ram effect