Bovine Breeding Management and Synchronization Flashcards
When is puberty generally seen?
At 50-60% body weight.
What is another factor than can affect puberty?
Nutrition
What is the bovine estrus cycle?
Estrus: Day 0
Metestrus: Days 1-4
Diestrus: Days 5-18
Proestrus: Day 19
When do you see the behavioural estrus in a cow?
Proestrus
What is the most definitive sign of estrus in cows?
Standing to be mounted
Is there any discharge during estrus?
Yes, clear discharge
What is a fairly accurate way of detecting estrus?
Increased walking/restlessness.
In the cow, when might you see bleeding?
Metestrus
NOTE: Not all cows will bleed.
In species other than the cow, when might you see bleeding?
Proestrus
What happens during metestrus?
Ovulation
During what phase of estrus is the CL dominant?
Diestrus
How is breeding carried out in a beef herd?
By a bull
How is breeding carried out in a dairy herd?
AI
What is the am-pm rule in dairy management?
Since cows ovulate AFTER estrus, if you detect estrus in the am, breed in the pm. If estrus is detected in the pm, breed the next am.
At what age are dairy heifers first bred?
~14-15 months
NOTE: Must meet proper weights at proper times.
How long is a cow’s gestation period?
9 months
What is the voluntary waiting period and how long is it?
It’s a time for the uterus to have a break and it is 60days long.
What is a dry-off and how long is it?
It’s a time for the mammary glands to have a break and it is 60 days long.
What is the production cycle of a dairy cow?
After reaching puberty and getting bred, they have their first calf and enter the milking herd (calf is hand raised), after voluntary waiting period, cow enters breeding herd again and the cow is dried off. The cycle continues.
What is a Q-Sum graph?
Gives info about the cows bred and the cows missed.
What’s a really good and easy way to enhance estrus detection?
Ensure proper nutrition.
Why should you provide the cows with proper footing?
They won’t mount if they can hurt themselves.
What are 4 estrus detection aids?
Tail-head pressure monitors
Estrus detector animals
Pedometry
Vaginal fluid electrical resistance (decreases during estrus)
How long is the beef herd breeding period?
21 days
What is a reasonable target for a beef herd?
60% bred on first 21-day cycle
20% on the second 21-day cycle
What are 2 major consequences of having poor conception rates?
Prolonged breeding season
Prolonged calving season
Describe the histrogram for a bull failure (makes you think he was injured).
Lots of cows bread in the first 21-day cycle, and then nothing for the next two 21-day cycles.
Kind of looks like bull horns
What does it mean to control the estrous cycle?
Onset of estrus may be hastened or delayed.
What does it mean to synchronize the estrous cycle?
Coordinated control of estrus in multiple animals.
What are 2 major advantages of control and synchronization of cycles?
Reduces the window of time when insemination is appropriate.
Allows scheduling of breeding/insemination
What is the general principle of estrus control and synchronization?
Shorten or lengthen the luteal phase.
What are the 3 main products for synchronizing estrus?
Prostaglandin
Progesterone
GnRH
What does PGF2a do?
Regression of the CL to shorten the luteal phase.
When will PGF2a have an effect?
Only between days 6-17
What are the 2 most common methods of using prostaglandings to shorten the luteal phase?
One shot
Two shot, 11 days apart
Why is the two shot method of PGF2a so great?
First shot brings 60-70% of cows into heat, second shot 11 days later brings >90% into heat.
What are 3 drawbacks to PGF1a synchronization?
Estrus detection rate
Labor is required
Not successful for timed artificial insemination
What are 2 devices used for synchronization with progesterone?
MGA (Melengestrol acetate)
CIDR
What is MGA (Melengestrol acetate)?
A feed through of progesterone to suppress estrus.
What timeframe is given for using a CIDR?
7 days
What does progesterone do?
Lengethens the luteal phase
What is given in conjunction to the progesterone and why?
PGF2a is given just in case there is a functional CL
If using a CIDR, when is PGF2a given?
When the CIDR is removed.
If using MGA, when is PGF2a given?
19 days after stopping the MGA, because the cows need a longer time to go through a silent heat.
What are 3 advantages to follicular synchronization?
Induces a synchronous emergencs of a new follicular wave.
Ovsynch, no heat detection
All cows undergo timed insemination (TAI)
What are 2 disadvantages of follicular synchronization?
Cows must be handled more
More expensive
What type of synchronization protocol is most often used in bovine breeding management?
Combination protocols
