Module 2- lifecycle & annual cycles of dairy cattle

Question 1

far-off

Answer 1

1 month before calving

Question 2

age of heifers to calve

Answer 2

22-23 months of age

Question 3

what day is dry off & how long is dry period

Answer 3

305, 60

Question 4

3 purposes of dry off period

Answer 4

rest, mammary involution & regrowth

Question 5

mean age of culling

Answer 5

4-5 years = 3 lactations

Question 6

2 main reasons for culling

Answer 6

1) infertility
2) mastitis

Question 7

how many days after calving is estrus?

Answer 7

14-17 days

Question 8

when are calves weaned

Answer 8

6-8 weeks

Question 9

what does overdevelopement of heifers cause

Answer 9

over condition mammary gland = lack some capacity

Question 10

culling target rate %

Answer 10

20-30%

Question 11

how much $ is put into a heifer before her 1st milking

Answer 11

$3000

Question 12

what % of culling is unknown

Answer 12

30%

Question 13

survivability curve

Answer 13

probability that an animal stays in the herd

Question 14

when is culling most common? Why?

Answer 14

start & end of lactation
- high risk of mastitis at these times

Question 15

disadvantage to keeping cows for 10 lactations

Answer 15

no new genetics

Question 16

transition period

Answer 16

last 3 weeks of gestation & first 3 weeks of lactation

Question 17

why is the transition period important

Answer 17

prepare for uterine involution & development

Question 18

2 things that occur during the transition period

Answer 18

1) inflammation
2) decrease in DM intake

Question 19

what are cows at risk for with rapid diet change?

Answer 19

rumen acidosis

Question 20

why do cows near parturition often face an immunocompromised state

Answer 20

Plasma vitamin A, E, selenium & zinc decline

Question 21

homeoresis

Answer 21

direct parturitioning nutrients towards survival of calf

Question 22

what occurs as cows reach peak lactation?

Answer 22

massive DMI for milk production = lags behind energy released through milk = cows lose body weight b/c have to mobilize own body reserves for demand of energy for milk production

Question 23

how much protein is mobilized during entire an lactation

Answer 23

15kg

Question 24

what can too negative of an energy balance cause?

Answer 24

risk of pregnancy rates going down

Question 25

negative energy balance for first ( ) weeks of lactation cycle, max feed intake at ( ) weeks, and minimum body weight at ( ) weeks

Answer 25

8-10
10-12
6-10

Question 26

peak milk yield persistency %

Answer 26

94-96%

Question 27

5 ways to improving peak milk yield

Answer 27

1) successful dry period
2) BCS management
3) 2-3x milking / day
4) optimize cow comfort
5) maximize feed intake around calving/early lactation

Question 28

5 phases in feeding dairy cows

Answer 28

1) early lactation
2) mid lactation
3) late lactation
4) far-off period
5) close up dry period

Question 29

early lactation
- when
- what happens to DMI

Answer 29

0-10 weeks
DMI increase

Question 30

mid lactation
- when
- what happens to DMI

Answer 30

10-30 weeks
max feed intake

Question 31

late lactation
- when
- what happens

Answer 31

30-44 weeks
BW gain
decline in milk

Question 32

what happens during far-off dry period

Answer 32

involution & regeneration of udder tissue
fetal requirements are much higher

Question 33

what happens during close up period

Answer 33

cell division & differentiation
calving soon