Cattle Reproduction

Question 1

When do heifers attain puberty?

Answer 1

At first estrus that is followed by a luteal phase

Question 2

Is puberty a chronological or physiological age?

Answer 2

Physiological

Question 3

What can influence the age of puberty?

Answer 3

Nutrition, Breed, skeletal growth, environment, body weight, management

Question 4

What is the average age of puberty for dairy and beef cattle?

Answer 4

Dairy-10-12 months

Beef- 11-15 months

Question 5

When is puberty in the bull?

Answer 5

the age at which the ejaculate contains sufficient sperm to impregnate the cow.

Question 6

Which bulls reach puberty quicker?

Answer 6

Holstein and crossbred bulls

Question 7

How long does the sperm per ejaculate increase?

Answer 7

18-24 months

Question 8

Are cattle photosensitive?

Answer 8

Mildly they may be

Question 9

What do the 4mm follicles and large antral follicles depend on?

Answer 9

4mm-FSH

Large antral- LH

Question 10

What hormone induces estrus?

Answer 10

E2 and decline of P4 which triggers the LH surge

Question 11

What are good indicators of estrus?

Answer 11

Vuscosity and ferning of the cervical mucous. Uterine tone and dilated cervix

Question 12

What causes the metestrus bleeding?

Answer 12

Estrogen increases the vascular growth of the endometrium, when E2 drops after ovulating this causes vulval discharges

Question 13

When is P4 levels high and cervical mucous thick?

Answer 13

Luteal phase

Question 14

What ways can cows in estrus be detechted?

Answer 14

V-Bulls or indicators on the rumps

Question 15

Describe ovulation in the cow?

Answer 15

10-12 hours after estrus and can be sped up bu using a v-bull. Just one follicle ovulates

Question 16

How long is the estrous cycle and estrus?

Answer 16

21 d and 18 hours

Question 17

How long is gestation length?

Answer 17

280 days

Question 18

Postpartum uterine involution is complete on what day?

Answer 18

45

Question 19

Is vision or small more of a turn on for the bull?

Answer 19

Vision

Question 20

Does the old or young bull service more cows?

Answer 20

Old because of the social ranking

Question 21

What position is the calf placed in the birthing canal?

Answer 21

Lateral or sternal

Question 22

What can improve fertility of repeat breeders?

Answer 22

GNRH

Question 23

When is the end of the postpartum anestrus?

Answer 23

First ovulation after postparnum, usually not associated with estrus

Question 24

What is the wave pattern of follicular development for a cow in estrus.

Answer 24

3 waves

Question 25

How long after the LH surge does ovulation occur?

Answer 25

24 hours

Question 26

Sperm production is highly correlated with wha?

Answer 26

Testicular size

Question 27

How long is required for completion of spermatogenesis?

Answer 27

61 days

Question 28

How much is ejaculated?

Answer 28

4-10 ml of semen that contain 1-2 billion sperm

Question 29

How many days after their calf should a cow have been in standing estrus and conceive?

Answer 29

Standing estrus- 60 days

Conceive- 85 days

Question 30

rBST can adversely affect reproduction if given when?

Answer 30

Before the first postpartum ovulation