IAP Flashcards
How do animals detect a change in season?
Light sends a signal to the pineal gland (Eye -> retino-hypothalamic tract -> suprachiasmatic nucleus -> bilateral superior cervical ganglia -> Pineal gland). No light signal=melatonin is released. Shorter days (winter)=more melatonin Longer days (summer)=less melatonin
Why do animals’ metabolisms decrease in winter?
Fat deposits change (more in winter). Gut transit time increases in winter to be able to absorb more nutrients. Animals in hibernation have a BMR of almost zero. Sheep and deer reduce BMR in winter.
At what time in the day is the hypothalamus sensitive to melatonin?
10 hours after daybreak; late afternoon
What are the effects of FSH?
Causes developing follicles to secrete inhibin (reduces FSH secretion) and oestrogen
What are the effects of LH?
Causes corpus luteum to produce progesterone
Causes developing follicles to secrete inhibin (inhibits FSH secretion) and oestrogen
Which lobe of the pituitary gland produces LH and FSH?
Anterior
During oestrus, why is the FSH surge not as big as the LH one?
Dominant follicle secretes inhibin, suppressing FSH
What percentage of cows have a 2 wave cycle?
80%
Remaining 20% have a 3 wave cycle
Why can cows still be seen bulling once pregnant?
Follicular waves continue during pregnancy
What does it mean if a cow is standing to be mounted?
She is in oestrus
What does it mean if a cow is mounting another cow?
She is in pre-oestrus
How long is oestrus in a horse?
When is ovulation?
What is the follicular growth per day?
7 days
24-48 hours before end of oestrus (Day 5)
3-5mm/day
Cows are most likely to ovulate if the follicle is how big in diameter?
What about horses?
Cows= 18-20mm Horses= above 35mm
In the bitch, what cells are present in the vagina during:
Anoestrus
Pro-oestrus
Di-oestrus
Anoestrus= parabasal cells (rounded cytoplasm, large stippled nucleus Pro-oestrus= Cornified cells (small nucleus, angled cytoplasm, numbers increase by 10% every day until oestrus-100%) Di-oestrus= 50% non-cornified cells on day 1
How can we shorten the luteal phase?
How can we extend it? Why would we want to?
Artificial prostaglandin
Progesterone-for synchronisation, or if we think luteolysis is occurring before the embryo has a chance to signal its presence
What is the effect of PGF2a?
Acts on the corpus luteum to cause luteolysis, forming a corpus albicans and stopping the production of progesterone
How far into pregnancy can you perform a rectal palpation in:
Cows?
Horses?
Cows: 35 days
Horses: 20-30 days
From when can you do an ultrasonography in cattle?
When can you see a whole fetus image?
Day 28-30
Day 59
When can progesterone be detected?
Between day 0 and 21
If levels are high 21 days after serving, likely to be pregnant
What is added to bulls’ sperm before AI?
Antibiotics
Extender to permit more insemination doses, prolong viability, maintain fertility and protect sperm from sudden pH or temp changes
How much sperm is contained inside one straw of ejaculate?
1 ejaculate gives how many straws?
15 million sperm
Over 300
Explain the AM/PM rule
Oestrus lasts 9-14 hours
Ovulation occurs 12-18 hours after oestrus ends
Need to allow time for sperm movement and maturation
Therefore if you see a cow in oestrus in the morning, serve her in the evening, and vice versa
What does MOET stand for?
Multiple ovulation and embryo transfer
How often can you flush a cow?
Every 8 weeks