Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
10 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
What is the purpose(s) of inclusion of an intravaginal device that releases progesterone into a treatment protocol for synchronising oestrus in cattle?
|
increases circulating concentrations of Progesterone to act as artificial CL
removal of deviced synchronises a decline in circulating concentrations of P4 or progestins and theoretically all animals will enter the follicular phase of the cycle many anoestrus cows will be induced into oestrus |
|
|
|
Outline the treatment program that is used with the OvSynch
program for synchronising ovulation. Explain the physiological basis for how the OvSynch protocol synchronises ovulation in cattle? What are the limitations of this protocol and how can responses be improved? |
Day 0: GnRH -> ovulate the dominat follicle & initiate new follicular wave
Day 7: PGF2 alpha -> induce luteolysis Day 9: GnRH -> induce ovulation of new dominate follicle +16h: TAI |
Limitations:
Dependend on stage of follicular development at time of initial GnRH injection (DF present ~70% of time) reduced pregancy rates in heifers Improve: Presynch -> 2 injections of PGF2alpha 14 d apart, OvSynch start 12-14d later -> increase no of follicles that respond to first GnRH Double OvSynch Ingecting PG and detecting heat for 3 days then starting the program with injection of GnRH 2 injections of PG(am & pm) 7 days after first GnRH injection can increase pregnancy rates |
|
|
Explain how two injections of prostaglandin F2α administered 14 days apart can be used to synchronise oestrus in cattle.
What are the advantages of this protocol and what are its limitations? |
Aim of PG programs: synchronise a decline in plasma concentrations of progesterone and initiate the follicular phase in treated animals
|
|
|
|
Explain the physiological reason for the variation in the interval
to oestrus following the administration of prostaglandin F2α to cattle. |
• Interval from injection of PG
to oestrus depends on the stage of follicular development at the time of treatment. • At the time of treatment: – Mature follicle present – time to oestrus will be short – Immature follicle present – time to oestrus longer – Dominant follicle present undergoing atresia - new wave emergence occurs, takes even longer to enter oestrus |
|
|
|
What precautions should you observe when using
prostaglandin F2α or its synthetic analogues to synchronise oestrus in cattle? |
• Can cause abortion if pregnant cows are accidently injected (<5
months (although some will abort up to 200 days), >8 months • Health and safety issues: respiratory difficulty, abortion. Do not allow people with high risk of respiratory difficulty, asthmatics, women of child bearing age to handle the drug. Avoid contact with skin and eyes. Wear gloves, wash off any spilt on skin |
|
|
|
Compare the use of oestradiol benzoate and GnRH at the start of a treatment protocol that involves the insertion of an intravaginal progesterone releasing insert.
|
GnRH: luteinisation of dominant follicle
EB: LH surge |
|
|
|
Compare the use of oestradiol benzoate and GnRH as methods
of inducing ovulation following removal of an intravaginal progesterone releasing insert that has been used to synchronise oestrus. |
?
|
|
|
|
Outline a protocol for synchronising a first oestrus and AI and then a second oestrus following AI in:
a) lactating dairy cows b) Maiden dairy heifers |
?
|
|
|
|
A farmer has synchronised oestrus in a group of cows and is
disappointed in the pregnancy rates that resulted. Outline how you would investigate this case. |
?
|
|
|
|
A manager calls you on the phone and says that he injected
beef cows with prostaglandin, none were in heat yesterday and 6 are in heat today. He thought that more would be in heat yesterday and is concerned that only 6 are in heat today and asks for your advice. • What questions would you ask the owner to help you to understand the situation that he is faced with? |
?
|
|
