Exam 1: Bovine Breeding Management and Synchronization

Question 1

Puberty is generally seen when the heifer

reaches _____ to _____% of its adult body weight

Answer 1

50 - 65%

Question 2

Bos _________ goes through puberty earlier than

Bos __________

Answer 2

Bos TAURUS earlier than Bos INDICUS

Question 3

T/F:

Heifers from bulls with large scrotal circumference

go through puberty earlier

Answer 3

TRUE

Question 4

Puberty occurs at

______ in Beef cows

_______ in Dairy cows

and

_______ in Zebu (Bos indicus) cows

Answer 4

Beef- 9-12 months

Dairy- 10-15 months

Zebu- 24-36 months

Question 5

In the bovine estrous cycle

Day 0 is

Answer 5

Estrus

Question 6

In the bovine estrous cycle

Day 1 - 4 is

Answer 6

metestrus

Question 7

What days of the bovine estrus cycle does

diestrus occur?

Answer 7

Day 5 - 18

Question 8

In the bovine estrous cycle,

Day 19 to behavioral estrus is called

Answer 8

proestrus

Question 9

Follicular maturation and peak estradiol (E2) levels

occur during this stage of the bovine estrous cycle

Answer 9

Estrus (Day 0)

Question 10

Ovulation, formation of the early CL, and progesterone (P4)

secretion occur during this stage of the bovine estrous cycle

Answer 10

Metestrus (Day 1-4)

Question 11

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

Answer 11

Diestrus (Day 5-18)

Question 12

Progesterone (P4) levels decrease while

Estradiol (E2) levels increase

occur during this stage of the bovine estrous cycle

Answer 12

Proestrus (Day 19-behavioral estrus)

Question 13

Dairy cows require a _____ day long “dry period”

before calving

Answer 13

60

Question 14

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

Answer 14

21

Question 15

On a histogram of a 21 day breeding period,

after 3 cycles, ideally, less than ______% of cows

will remain open.

Answer 15

10%

Question 16

What does “control” of the estrous cycle imply?

Answer 16

Onset of estrous that is hastened or delayed

Question 17

What does synchronization of the estrous cycle imply?

Answer 17

the coordinated control of estrus in multiple animals

Question 18

In order to control and synch estrous cycles,

you can either shorten or lengthen the ________ phase

Answer 18

luteal

Question 19

What are the 3 main products used for manipulation of estrus?

Answer 19

Prostaglandin (PG)

Progesterone (P4)

GnRH

Question 20

Lutalyse/Estrumate is the drug used for

_________ programs.

Answer 20

Prostaglandin

Question 21

What happens when a cow is injected with

Lutalyse/Estrumate (PGF2a)?

Answer 21

CL regresses

Estrus displayed in 2 - 5 days

Question 22

What days of the cycle would you give

Lutalyse/Estrumate (PGF2a)?

Answer 22

Days 6 - 17 ONLY!

(After 17, those cows will be going into estrus anyway)

Question 23

In the 2 shot method of a prostaglandin F2a program,

2 shots are given ______ days apart.

Answer 23

11 days

Question 24

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.

Answer 24

1st shot PGF2a= 60 - 70% in heat

2nd shot = >90% in heat

Question 25

What 2 products can be used in a progesterone program

for estrous control and synch?

Answer 25

MGA and CIDR

Question 26

If MGA (progesterone) is consumed for greater than 14 days,

there is a risk of __________ estrus

Answer 26

subfertile

Question 27

How does CIDR (progesterone) work?

Answer 27

7 days inside cow

Then, take it out and give a shot of prostaglandin,

she will fall into heat

Question 28

Progesterone control programs using MGA and CIDR

________ the luteal phase

Answer 28

lengthen

Question 29

In this method of follicular synchronization,

_______ is used to induce

synchronous emergence of a new follicular wave

Answer 29

GnRH (Cystrolrelin)