Bovine Breeding Management and Synchronization, Female Cyclicity Flashcards
Identify diestrus on this chart:
What is the AM-PM rule for breeding in dairy herds?
If you see heat in the morning, breed her in the afternoon (10-12 hour difference)
T/F: Dairy herds are mostly bull bred
False
Beef herds are mostly bull bred.
Dairy herds are mostly artificially inseminated
What are the two general phases of the estrous cycle?
follicular phase and luteal phase
- Follicular phase includes proestrus and estrus
- Luteal phase includes metestrus and diestrus
What is the most definitive sign of estrus in cows?
standing to be mounted
Follicular synchronization can be acheived by giving an exogenous source of GnRH to induce a synchronous emergence of a new follicular wave.
T/F: When giving GnRH, it is typically given by itself to avoid adverse drug interactions
False
Usually when we give GnRH, it is in combination with some other synchronization drug or technique
What portion of the bovine estrous cycle is the period of CL dominance through luteolysis?
Diestrus
This is a Y-device that is placed in the cranial vagina to have progesterone released over time:
Controlled Intravaginal Drug Release (CIDR)
What are the three products used for manipulation of the estrous cycle?
prostaglandin, progesterone, GnRH
The period between one estrus and the next is termed:
estrous cycle
- ESTRUS is a noun (“The cow is displaying estrus”)
- ESTROUS is an adjective (“The length of the estrous cycle in the pig is 21 days”)
The three types of cyclicity are:
- Polyestrus
- Seasonally polyestrus
- Monoestrus
The #1 characteristic for all species in order for you to know that they have hit puberty is:
the ability of the hypothalamus to make its own GnRH
What is the position of this calf?
- Anterior, longitudinal
- Dorsosacral
- Front limbs extended, head retained
Dorsosacral
What are the four stages of the estrous cycle?
proestrus, estrus, metestrus, diestrus
What is the dominant hormone during the luteal phase of the estrous cycle?
progesterone (P4)
What hormone is most prominent during estrus?
estrogen
Identify the luteal phase on this graph:
What is the dominant hormone during the follicular phase of the estrous cycle?
estrogen (E2)
T/F: Lutalyse® only works during metestrus
False
- Lutalyse® only works during diestrus.*
- It works by lysing the CL. In metestrus (day 0-6), prostaglandin will have no effect. Diestrus (day 6-17) is the window when prostaglandin will have its effect because there is a CL.*
What stage of labor is this cow in?
Stage 2
What scale do we use for body condition scoring in beef herds?
1 to 9
T/F: Metestrus is the stage of the estrous cycle where progesterone becomes the dominant hormone
True
The time period when farmer stops milking a cow; gives her a break from milking is known as:
dry-off period
gives her mammary glands time to recover
The time period after calving in which a cow is not bred is called:
voluntary waiting period (VWP)
Typically 45-65 days (60 days), so uterus can involute again and repair and go back to normal size. Length is determined by physiology, economics, producers.
T/F: Beef herds are mostly bull bred
True
Identify metestrus on this chart:
Which estrus synchronization method shortens the luteal phase of the cycle?
prostaglandin programs
Lutalyse®
Where’s in the estrous cycle is Waldo?
diestrus
During which stage of the estrous cycle does the corpus luteum form?
metestrus
Identify the point of ovulation on this graph:
What is the dominant ovarian structure during the follicular phase of the estrous cycle?
follicles
Sustained secretion of high levels of progesterone (P4) from a mature corpus luteum occurs during which stage of the estrous cycle?
diestrus
Which estrus synchronization method lengthens the luteal phase of the cycle?
progesterone programs
Melengestrol Acetate, Controlled Internal Drug Release (CIDR)
If you note a bit of bloody vaginal discharge, the cow is likely in what stage of estrous?
Metestrus
Is this histogram appropriate for a beef conception rate?
Yes
We want ~60% of herd to be pregnant in the 1st cycle. In the 2nd and 3rd cycle we are playing clean up, and we want less than 10% to be open at the end. Woohoo!
This progesterone product is mixed in with the feed and acts to suppress estus/prevent ovulation
Melengestrol Acetate (MGA)
Peak estrogen (E2) secretion occurs during which stage of the estrous cycle?
estrus
Dairy herd heifers are bred at ~_______ of age
14-15 months
They should calve at ~22-24 months. If bred too early they are more at risk of dystocia or abortion because they aren’t big enough to carry a calf to term – if your arm does not fit, the baby will not fit!
Puberty is generally seen when heifer reaches ____% adult body weight
50-65%
- Influenced by genotype
- Inbreed later onset
- Cross-breeds sooner onset
- Bos taurus earlier than Bos indicus
- Heifers from bulls large scrotal circumference
Identify the follicular phase on this graph:
The voluntary waiting period in a dairy herd refers to the time during which the cow is:
not bred
The period of sexual receptivity (heat) is termed:
estrus
- ESTRUS is a noun (“The cow is displaying estrus”)
- ESTROUS is an adjective (“The length of the estrous cycle in the pig is 21 days”)
Identify estrus on this chart:
What is the dominant ovarian structure during the luteal phase of the estrous cycle?
corpus luteum
What is the most likely cause of this type of histogram in a 21 day breeding period?
bull failure
The bull may have become injured, etc. (example: penile hematoma)
What are some reasons for this graph in a 21-day breeding season in beef herds?
- Poor Conception rates
- Prolonged breeding season
- Prolonged calving season
- Large number of open cows
