Dairy cow nutrition

Question 1

how efficient are dairy cows

Answer 1

90% of the efficiency of pure corn/soy protein diet

Question 2

when do you want heifers to calve

Answer 2

2 years

Question 3

how often should cow have a calf

Answer 3

every 13-14 months

Question 4

how long is dry period

Answer 4

2 months at end of pregnancy

Question 5

how many calves do cows usually have before being replaced

Answer 5

3

Question 6

how many times are cows milked/day

Answer 6

2-3

Question 7

does reticulum have enzymes

Answer 7

no

Question 8

rumen lining

Answer 8

papillae lining –> mucosa

Question 9

what does rumen break feeds down into and synthesize

Answer 9

VFA, amino acids, protein, some vitamins

Question 10

does omasum have enzymes

Answer 10

no

Question 11

does abomasum have enzymes

Answer 11

yes –> glandular

Question 12

what does abomasum secrete

Answer 12

HCl, mucin, pepsinogen, rennin (clots casein), lipase

Question 13

how much of feed is digested in rumen

Answer 13

70%

Question 14

what do microorganisms produce

Answer 14

VFAs –> primary energy source, protein

Question 15

what happens to excess hydrogen in rumen

Answer 15

attached to carbon to produce methane (can’t make CO2, H2O because no O2)

Question 16

what is fiber broken down into in rumen

Answer 16

acetate, butyrate (2c, 4c)

Question 17

what are starches and sugars broken down into in rumen

Answer 17

propionate (3c)

Question 18

what can cow convert into glucose

Answer 18

propionate (in the liver)

Question 19

body condition during calving, peak, dry off

Answer 19

• calving: >3
• peak: >2.5
• dry off: >3.25

Question 20

lactation stages and times

Answer 20

• early: 7-70d
• peak: 71-140d
• mid and late: 140-“305”

Question 21

do different lactation stages need a different ration?

Answer 21

no - just different amounts

Question 22

dietary changes dry cow –> transition

Answer 22

• different ration for dry cow than lactation

- transition from dry to lactation diet 3w prior to calving and 1 week after

Question 23

early lactation

Answer 23

• rapid increase in milk production
• negative energy balance
• increasing dry matter intake
• requires high protein

Question 24

peak production

Answer 24

• max dry matter intake
• highest milk production
• sets pattern for whole lactation
• limited by dry matter intake
• high energy density, protein, bypass protein

Question 25

mid to late lactation

Answer 25

• production declines
• restore body condition
• support fetus (most growth in last trimester)

Question 26

dry period

Answer 26

• separate ration (higher forage)
• low energy density
• low calcium, acidifying diet to reduce hypocalcemia
• allow exercise

Question 27

transition period

Answer 27

• last 2-3w before calving through first 2 weeks of lactation
• most stressful time in cycle (disease)
• DM intake low

Question 28

steps in producing TMR

Answer 28

• base vitamin/mineral mix
• protein mix (protein and concentrate grain mix)
• corn/other grain
• byproducts or commodities
• premix
• forages

Question 29

dairy feeding systems

Answer 29

• stanchion barns (component feeding or TMR)
• freestall barns (TMR)
• others