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Feeds lecture > Dairy Nutrition > Flashcards

Dairy Nutrition Flashcards

1
Q

what state ranks 1st in dairy cow inventory

A

california

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2
Q

where does Texas rank in terms of dairy cattle inventory

A

4th

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3
Q

what percent of total US dairy inventory does Texas hold

A

6.8%

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4
Q

trend of average dairy herd size and number of herds

A

size has increased and number has decreased

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5
Q

what are NE values affected by

A

-nutrition composition of feeds
-physiological function of animal

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6
Q

how does nutritional composition of feed affect NE

A

fiber has higher heat increment

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7
Q

which has a higher heat increment: growth or lactation

A

growth

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8
Q

T/F NE for lactation will always be higher? why/why not?

A

TRUE, heat increment is low

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9
Q

equation for NE

A

NE = ME- HI

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10
Q

T/F lactating cattle are less efficient than growing cattle

A

FALSE. they are more efficient

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11
Q

why is it impossible to meet lactating cows nutrient demands

A

demands exceed DMI

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12
Q

how do dairy cows meet nutrient requirements when feed doesnt

A

mobilization of fat

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13
Q

dairy cow production phases

A
  1. early lactation
  2. mid lactation
  3. late lactation
  4. dry period
  5. transition period
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14
Q

early lactation characteristics

A

-0-10 wks
-peak milk production at 3-6 wks

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15
Q

mid lactation characteristics

A

-10-24 wks
-milk yield begins to decrease
-peak DMI at 11-13wks

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16
Q

late lactation characteristics

A
  • > 24 wks
    -decreased milk yield
    -cow regains body tissue reserves
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17
Q

dry period characteristics

A

-5-8 wks
-late pregnancy

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18
Q

transition period characteristics

A

-2-3 wks
-late pregnancy
-prepare for lactation

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19
Q

how does lactation rank in physiological priority throughout milking phases

A

Early: highest priority
Middle: 2nd(behind repro)
Late: lowest(repro, growth, maintenance)

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20
Q

issue with feeding high grain diets to dairy cows

A

damage to rumen papillae and depress milk fat

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21
Q

milk fat thresholds for $/cwt increase

A

.1% above 3.2%
bonus .1% over 3.5%

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22
Q

what factors are producers paid based on

A

milk volume
milk composition
milk quality

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23
Q

what threshold of milk quality are producers paid extra

A

$.03 per 20,000?l below somatic cell count of 400,000/L

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24
Q

how does rumination affect digestion

A

salivation increases rumen pH, increased pH is favorable for fiber loving microbes

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25
Q

why is the acetate:propionate ratio important

A

acetate helps with milk fat production

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26
Q

what rumen pH does acetate prefer

A

higher pH

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27
Q

what rumen pH does propionate prefer

A

lower pH

28
Q

rule of thumb for adequate fiber levels

A

-forage:concentrate ration of 40:60
-minimum 21% ADF
-minimum 1-1.5% BW as forrage

29
Q

what is effective fiber dependent on

A

-particle size(larger=effective)
-amount of chemical fiber(CF, ADF, NDF)
-type of fiber(amount lignin)

30
Q

how does effective fiber affect rumination

A

increased effective fiber increases rumination

31
Q

how does the roughage index value effective fiber

A

measures amount of time cow spends ruminating(calculated as minutes chewing per unit DM)

32
Q

methods to measure effective fiber

A

-roughage value index
-particle size separator
-sensor technologies

33
Q

how does the particle size separator measure effective fiber

A

sorts into large, medium, and small
large:6-10%
medium:30-50%
small:40-60%

34
Q

how do sensor technologies measure effective fiber

A

collar monitors rumination

35
Q

what reproduction phase will the cow have a drop in feed intake

A

a few days before calving

36
Q

short term benefits of proper fiber

A

increased milk fat synthesis

37
Q

long term benefits of proper fiber

A

prevent acidosis and rumen burnout

38
Q

nutritional factors(other than fiber) that affect milk composition, and how?

A

-type of grain: faster fermentable grains increase milk depression
-grain processing: more processed = faster fermentation
-dietary buffers: increase rumen pH to minimize milk fat depression
-dietary fats: decrease milk protein

39
Q

grain rates of fermentation(fastest to slowest)

A

Fastest: Wheat
Barley
Slower: Milo, Corn

40
Q

situations where dairy buffers are beneficial

A

high corn-silage diets
high grain diets
low effective fiber diets
cows off feed(early lactation)

41
Q

what and how much buffer can be fed to cows

A

sodium bicarbonate @ 1% of DM

42
Q

how much fat can you add to cattle diet

A

5%, most feeds contain 3% fat

43
Q

issues with adding more than the acceptable amount of fat to the diet

A

-decreased feed intake
-decreased fiber digestion
-increased digestive upset

44
Q

how much fat is acceptable in cow diets

A

8%

45
Q

benefits of adding fat to dairy cows

A

-increased milk production
-less weight loss
-less impacted by heat stress
-decreased heat increment
-reduce ketosis
-enhance reproductive performance

46
Q

cheapest fat sources

A

plant seed oils

47
Q

most expensive fat sources

A

processed fat sources

48
Q

mid range fat sources

A

unprocessed fat

49
Q

purpose of bypass fats

A

dont disrupt rumen fermentation of fiber

50
Q

feeding systems for lactating dairy cows

A

Traditional
TMR

51
Q

disadvantages of traditional feeding system

A

estimating forage DMI and nutritional quality makes it difficult

52
Q

what is the traditional feeding system

A

forage and concentrates fed separately

53
Q

what is Total mixed ration feeding system

A

forages and concentrates mixed together

54
Q

disadvantages of TMR

A

all forages must be harvested

55
Q

advantages of TMR

A

-cows dont choose which forage to eat(cows are forced to eat correct balance of forage and concentrate)
-multiple small meals help maintain stable pH
-easier to feed various production groups
-reduce incidence of social dominance

56
Q

advantages of traditional feeding system

A

-no need for harvesting forages
-equipment is less expensive

57
Q

new method for preventing milk fever

A

dietary cation-anion balance(DCAB)

58
Q

how does DCAB work

A

negative DCAB before calving lowers milk fever(feed negative balance during stage 5)

59
Q

cation(alkalogenic) macrominerals

A

Na and K

60
Q

anion(acidogenic) macrominerals

A

Cl and S

61
Q

what is the recommended DCAB

A

-10 to -15 meq/100 g diet DM

62
Q

challenges to feeding negative DCAB

A

-anion salts are more expensive
-anion slats are less palatable

63
Q

symptoms of ketosis

A

-elevated ketone bodies
-depressed blood glucose levels
-decreased appetite
-decreased milk production
-distinctive acetone

64
Q

T/F ketosis is very deadly to dairy cattle

A

FALSE. cows rarely die from it

65
Q

occurrence of ketosis

A

-2-15% get clinical ketosis
-50% get borderline ketosis
-most cases occur within 60 days of calving

66
Q

prevention of ketosis

A

-avoid excess BCS at calving
-good transition diet
-maximize DMI during early lactation
-feed glucose precursors
-feed niacin(b-complex vitamin)

Feeds lecture (18 decks)

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