Exam 1: Bovine Breeding Management and Synchronization Flashcards
Puberty is generally seen when the heifer
reaches _____ to _____% of its adult body weight
50 - 65%
Bos _________ goes through puberty earlier than
Bos __________
Bos TAURUS earlier than Bos INDICUS
T/F:
Heifers from bulls with large scrotal circumference
go through puberty earlier
TRUE
Puberty occurs at
______ in Beef cows
_______ in Dairy cows
and
_______ in Zebu (Bos indicus) cows
Beef- 9-12 months
Dairy- 10-15 months
Zebu- 24-36 months
In the bovine estrous cycle
Day 0 is
Estrus
In the bovine estrous cycle
Day 1 - 4 is
metestrus
What days of the bovine estrus cycle does
diestrus occur?
Day 5 - 18
In the bovine estrous cycle,
Day 19 to behavioral estrus is called
proestrus
Follicular maturation and peak estradiol (E2) levels
occur during this stage of the bovine estrous cycle
Estrus (Day 0)
Ovulation, formation of the early CL, and progesterone (P4)
secretion occur during this stage of the bovine estrous cycle
Metestrus (Day 1-4)
The period of CL dominance through luteolysis
controlled by IFN-tau (continue pregnancy)
or
PFG2a (luteolysis)
occur during this stage of the bovine estrous cycle
Diestrus (Day 5-18)
Progesterone (P4) levels decrease while
Estradiol (E2) levels increase
occur during this stage of the bovine estrous cycle
Proestrus (Day 19-behavioral estrus)
Dairy cows require a _____ day long “dry period”
before calving
60
Beef herds are on _____ day breeding periods.
Histograms are used to analyze each bulls
conception rates and the percentage of cows pregnant
during the period.
Beef cows are allowed to copulate naturally
while dairy cows use AI because those bulls are dangerous
21
On a histogram of a 21 day breeding period,
after 3 cycles, ideally, less than ______% of cows
will remain open.
10%
What does “control” of the estrous cycle imply?
Onset of estrous that is hastened or delayed
What does synchronization of the estrous cycle imply?
the coordinated control of estrus in multiple animals
In order to control and synch estrous cycles,
you can either shorten or lengthen the ________ phase
luteal
What are the 3 main products used for manipulation of estrus?
Prostaglandin (PG)
Progesterone (P4)
GnRH
Lutalyse/Estrumate is the drug used for
_________ programs.
Prostaglandin
What happens when a cow is injected with
Lutalyse/Estrumate (PGF2a)?
CL regresses
Estrus displayed in 2 - 5 days
What days of the cycle would you give
Lutalyse/Estrumate (PGF2a)?
Days 6 - 17 ONLY!
(After 17, those cows will be going into estrus anyway)
In the 2 shot method of a prostaglandin F2a program,
2 shots are given ______ days apart.
11 days
In the 2 shot method of a prostaglandin F2a program,
the first shot brings ______% into heat in 2-5 days.
After the second shot, >____% are in heat.
1st shot PGF2a= 60 - 70% in heat
2nd shot = >90% in heat
What 2 products can be used in a progesterone program
for estrous control and synch?
MGA and CIDR
If MGA (progesterone) is consumed for greater than 14 days,
there is a risk of __________ estrus
subfertile
How does CIDR (progesterone) work?
7 days inside cow
Then, take it out and give a shot of prostaglandin,
she will fall into heat
Progesterone control programs using MGA and CIDR
________ the luteal phase
lengthen
In this method of follicular synchronization,
_______ is used to induce
synchronous emergence of a new follicular wave
GnRH (Cystrolrelin)
