Exam 3- Cooowwwssss Flashcards
(172 cards)
T/F normal uterine tubes are palpable in a cow
False, unless there is pathology
What parts (stages) of follicles are palpable in a cow’s ovary
Tertiary follicles, corpus hemorrhagicum, corpus luteum
Explain the hormones involved in the positive feedback system between the ovaries and the hypothalamus and anterior pituitary
The ovaries release estradiol which stimulates the hypothalamus to release GnRH which acts on the anterior pituitary to release FSH and LH which act on the ovary to stimulate follicular genesis
Which hormone comes from the ovary and results in negative feedback on the hypothalamus (and thus the release of GnRH)
Progesterone from the CL (Also when progesterone is high estradiol will act as inhibitory)
At what phase of the estrus cycle is estradiol released from the ovary
Later proestrus (advanced follicular stage)
At what stage of the estrus cycle is progesterone released by the corpus luteum
Luteal phase (metestrus and diestrus)
How long is the average bovine estrus cycle and how many phases does it have
21 days- follicular phase (2-3 days) and luteal phase
What hormones are increasing/ high during the follicular phase and which hormone is decreasing
Estradiol, LH, and FSH are increasing and progesterone is decreasing (luteolysis)
What causes estradiol to increase in proestrus in the follicular phase
Developing follicles (create positive feedback to cause a GnRH surge in the hypothalamus)
The dominant follicle is producing estradiol with other follicles but what hormone is the dominant follicle also producing
Inhibit to suppress FSH and suppress the formation of other follicles
At what specific phase does estradiol peak
Estrus
What are secondary signs of estrus
Clear vaginal discharge, vulvar edema, vaginal hyperemia, increased physical activity
What induces ovulation and when does ovulation occur
The high levels of LH and ovulation occurs 12 hours after the end of estrus
What converts the corpus hemorrhagicum to a corpus luteum
Pulses of LH
What signals the start of metestrus and what hormone is increasing during this time, how long is metestrus
Ovulation and progesterone begins to increase, metestrus is 3-5 days
During diestrus progesterone is high, but what other hormones are released in low frequency pulses
FSH and LH to stimulate follicular development
What action does progesterone have on the myometrium
Relaxation to create a quiescent uterus
Along with progesterone, what other hormone is released by the corpus luteum
Oxytocin
What does oxytocin stimulate the release of
PGF2 alpha from the endometrium
What does PGF2 alpha do
Causes luteolysis (destruction of CL) which results in a decrease in progesterone
T/F many follicles may develop but only one becomes the dominant ovulatory follicle which the rest undergo atresia
True
T/F follicles are developing throughout the estrus cycle but the one that becomes the dominant follicle can fully develop to ovulation because progesterone is high
False progesterone must be low for the follicle to develop fully
T/F using the observation method of pregnancy diagnosis is cost-effective in the long run
False, it is not as reliable. It doesn’t require much training but it lacks in sensitivity and specificity which increases costs in the long run. Also if you are looking for a non-return to estrus, there are lots of things that can cause that, not just pregnancy (ovarian cysts, hydrometra, metritis, poor nutrition, etc.) Also, some pregnant females can show behavioral estrus
What is the most common and accurate method of pregnancy detection in cows
Trans-rectal palpation