Flashcards in Bovine Estrous Cycle Deck (53)
When is puberty in cattle?
What is the seasonality of cattle reproduction?
How long is the estrus cycle of a cow?
Which hormone acts directly on a follicle to stimulate the growth of the follicles?
Which hormone causes ovulation of a mature follicle?
What hormones does a follicle secrete?
Estrogen and inhibin
Which homone secreted by a follicle causes a positive feedback loop to the hypothalamus?
What does a CL produce?
What hormone maintains pregnancy?
How does progesterone affect the hypothalamic and pituitary hormones?
Negative feedback on LH
What hormone can destroy/lyse a CL?
How many follicular waves does a cow have?
2-3 waves per cycle w/one dominant follicle per wave
When does the LH surge occur in relation to follicular waves?
LH surge w/last wave
What is the optimal breeding time for a cow?
Middle of estrus to 6h after end of estrus
How long after ovulation is an ovum fertilizable?
What are indications for estrus synchronization in cows?
Increased mating efficiency, shortening of birthing season
What are techniques of estrogen synchronization?
P4, PGF2a, both, or GnRH + PGF
Which estrogen synchronization technique acts as an "artificial CL"?
How does progesterone administration synchronize a cow?
Suppresses LH to prevent ovulation
How long do you have to give exogenous progesterone for synchronization to work?
What device is used for progesterone therapy adminsitration?
What is the protocos for prostaglandin estrous syncrhonization?
2 inj 14d apart
The first PGF injection causes luteolysis in what % of females?
Which PGF injection syncrhonizes majority of the herd?
What is the Ovsynch program?
GnRH + PGF
What is the goal of the first GnRH administration of the Ovsynch program?
Luteinization or ovulation of follicles
How soon after GnRH injection is PGF administered?
When is the second GnRH dose administered to a cow?
2d after PGF
What is the goal of the 2nd GnRH dose of the Ovsynch program?
Induce ovulation of the next follicle (at the same time as the rest of the herd)