Bovine Breeding Management and Synchronization, Female Cyclicity

Question 1

Identify diestrus on this chart:

Answer 1

Question 2

What is the AM-PM rule for breeding in dairy herds?

Answer 2

If you see heat in the morning, breed her in the afternoon (10-12 hour difference)

Question 3

T/F: Dairy herds are mostly bull bred

Answer 3

False

Beef herds are mostly bull bred.

Dairy herds are mostly artificially inseminated

Question 4

What are the two general phases of the estrous cycle?

Answer 4

follicular phase and luteal phase

• Follicular phase includes proestrus and estrus
• Luteal phase includes metestrus and diestrus

Question 5

What is the most definitive sign of estrus in cows?

Answer 5

standing to be mounted

Question 6

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

Answer 6

False

Usually when we give GnRH, it is in combination with some other synchronization drug or technique

Question 7

What portion of the bovine estrous cycle is the period of CL dominance through luteolysis?

Answer 7

Diestrus

Question 8

This is a Y-device that is placed in the cranial vagina to have progesterone released over time:

Answer 8

Controlled Intravaginal Drug Release (CIDR)

Question 9

What are the three products used for manipulation of the estrous cycle?

Answer 9

prostaglandin, progesterone, GnRH

Question 10

The period between one estrus and the next is termed:

Answer 10

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”)

Question 11

The three types of cyclicity are:

Answer 11

1. Polyestrus
2. Seasonally polyestrus
3. Monoestrus

Question 12

The #1 characteristic for all species in order for you to know that they have hit puberty is:

Answer 12

the ability of the hypothalamus to make its own GnRH

Question 13

What is the position of this calf?

• Anterior, longitudinal
• Dorsosacral
• Front limbs extended, head retained

Answer 13

Dorsosacral​

Question 14

What are the four stages of the estrous cycle?

Answer 14

proestrus, estrus, metestrus, diestrus

Question 15

What is the dominant hormone during the luteal phase of the estrous cycle?

Answer 15

progesterone (P4)

Question 16

What hormone is most prominent during estrus?

Answer 16

estrogen

Question 17

Identify the luteal phase on this graph:

Answer 17

Question 18

What is the dominant hormone during the follicular phase of the estrous cycle?

Answer 18

estrogen (E2)

Question 19

T/F: Lutalyse® only works during metestrus

Answer 19

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.*

Question 20

What stage of labor is this cow in?

Answer 20

Stage 2

Question 21

What scale do we use for body condition scoring in beef herds?

Answer 21

1 to 9

Question 22

T/F: Metestrus is the stage of the estrous cycle where progesterone becomes the dominant hormone

Answer 22

True

Question 23

The time period when farmer stops milking a cow; gives her a break from milking is known as:

Answer 23

dry-off period

gives her mammary glands time to recover

Question 24

The time period after calving in which a cow is not bred is called:

Answer 24

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.

Question 25

T/F: Beef herds are mostly bull bred

Answer 25

**True**

Question 26

Identify metestrus on this chart:

Answer 26

Question 27

Which estrus synchronization method shortens the luteal phase of the cycle?

Answer 27

**prostaglandin programs** *Lutalyse®*

Question 28

Where's in the estrous cycle is Waldo?

Answer 28

**diestrus**

Question 29

During which stage of the estrous cycle does the corpus luteum form?

Answer 29

**metestrus**

Question 30

Identify the point of ovulation on this graph:

Answer 30

Question 31

What is the dominant ovarian structure during the follicular phase of the estrous cycle?

Answer 31

**follicles**

Question 32

Sustained secretion of high levels of progesterone (P4) from a mature corpus luteum occurs during which stage of the estrous cycle?

Answer 32

**diestrus**

Question 33

Which estrus synchronization method lengthens the luteal phase of the cycle?

Answer 33

**progesterone programs** *Melengestrol Acetate, Controlled Internal Drug Release (CIDR)*

Question 34

If you note a bit of bloody vaginal discharge, the cow is likely in *what stage of estrous*?

Answer 34

**Metestrus**

Question 35

Is this histogram appropriate for a beef conception rate?

Answer 35

**Yes** *We want ~60% of herd to be pregnant in the 1^st cycle. In the 2^nd and 3^rd cycle we are playing clean up, and we want less than 10% to be open at the end. Woohoo!*

Question 36

This progesterone product is mixed in with the feed and acts to suppress estus/prevent ovulation

Answer 36

**Melengestrol Acetate (MGA)**

Question 37

Peak estrogen (E2) secretion occurs during which stage of the estrous cycle?

Answer 37

**estrus**

Question 38

Dairy herd heifers are bred at ~\_\_\_\_\_\_\_ of age

Answer 38

**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!*

Question 39

Puberty is generally seen when heifer reaches \_\_\_\_% adult body weight

Answer 39

**50-65%​** * Influenced by genotype * Inbreed later onset * Cross-breeds sooner onset * *Bos taurus* earlier than *Bos indicus* * Heifers from bulls large scrotal circumference

Question 40

Identify the follicular phase on this graph:

Answer 40

Question 41

The voluntary waiting period in a dairy herd refers to the time during which the cow is:

Answer 41

**not bred**

Question 42

The period of sexual receptivity (heat) is termed:

Answer 42

**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")

Question 43

Identify estrus on this chart:

Answer 43

Question 44

What is the dominant ovarian structure during the luteal phase of the estrous cycle?

Answer 44

**corpus luteum**

Question 45

What is the most likely cause of this type of histogram in a 21 day breeding period?

Answer 45

**bull failure** *The bull may have become injured, etc. (example: penile hematoma)*

Question 46

What are some reasons for this graph in a 21-day breeding season in beef herds?

Answer 46

* Poor Conception rates * Prolonged breeding season * Prolonged calving season * Large number of open cows