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ANSC 460 > Lab material > Flashcards

Lab material Flashcards

1
Q

3 main hormones involved in reproduction

A

GnRH, FSH, LH

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2
Q

when does puberty in heifers occur?

A

8 months

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3
Q

what % of mature body weight is reached at puberty?

A

30-40%

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4
Q

what % of mature body weight is reached at breeding?

A

55% (13-15 months)

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5
Q

5 factors that influence onset of puberty

A

age, body weight, genetics, season of birth & bull exposure

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6
Q

gonadal regulation

A

progesterone inhibits LH surge
estrogen inhibits FSH secretion

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7
Q

what occurs with ovulation? (3)

A

corpus lutuem regresses, progesterone decreases & LH surge

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8
Q

why do you need a second wave for ovulation?

A

as follicle gets bigger = more estradiol = suppresses progesterone = no ovulation

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9
Q

what drives frequency of FSH

A

estrogen levels

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10
Q

what sign is shown when in peak estrus

A

standing to be mounted

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11
Q

signs of estrus

A
  • mucus
  • swollen vulva
  • flehmen response
  • decreased feed
  • decreased milk
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12
Q

1st sign of estrus

A

chin resting

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13
Q

metestrus hemorrhage

A

post ovulatory bleeding

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14
Q

when to AI cows

A

breed 12 hours after standing heat
- use AM-PM rule

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15
Q

when should you AI?

A

when estrus is observed

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16
Q

AM-PM rule

A

if cow is seen in estrus in AM = AI in PM

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17
Q

gestationn length

A

275-290 days

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18
Q

a producer asks you for help identifying while synchronization did not work. What factors might play into this? (5)

A

1) timing of hormones/AI
2) were animals cycling?
3) nutritional management
4) semen quality
5) experienced AI technician?

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19
Q

2 ways to manipulate onset of estrus:

A

1) OvSynch-> GnRH injection #2 and AI are not done at same time
- higher success with cycling cows

2) CoSynch-> GnRH injection #2 and AI are done at same time
- progesterone device is expensive
- use in heifers & non-cycling cows = better success rate

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20
Q

do heifers or cows have a longer estrus duration?

A

heifers

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21
Q

does bos taurus or bos indicus have longer estrus duration?

A

bos taurus

22
Q

how long is the estrous cycle

A

21 days

23
Q

what are good conception rates

A

> 55%

24
Q

4 roles of lactanet

A

1) milk recording
2) herd management software
3) genetic evaluations
4) advisory services

25
Q

3 disadvantages of DHI testing

A
  • have to pay for service
  • someone is in parlour all day
  • some farmers don’t see value
26
Q

what % of herd do you want to be 1st lactation?

A

30%

27
Q

4 most important criteria for NDS

A

1) body weight
2) milk production/composition
3) DMI
4) accurate nutrient analysis of feed ingredients

28
Q

what 3 hormones increase blood Ca?

A

PTHrP, PTH & calcitrol

29
Q

major galactopoietic hormone

A

bovine somatotropin

30
Q

name 5 outcomes of improper milking techniques

A

1) decreased milk production
2) high SCC
3) decreased profitability
4) mastitis
5) hyperkeratosis

31
Q

goldilocks diet during close up period

A

moderate energy to cows maintain BCS

32
Q

how do we properly manage a sikage pit?

A

level face
remove at least 30cm
cut plastic 2x / week

33
Q

what does milk get tested for? (5)

A

1) temp
2) IBC
3) antibiotic residues
4) milk components
5) SCC

34
Q

3 benefits to social rearing of calves

A

1) reduced fear to novel objects
2) increased cognitive ability
3) increased starter intake

35
Q

if you have colostrum tested at 25% brix (equivalent to 67g/l of IgG), how many liters should be fed to reach 200-300 grams of IgG>

A

3 - 4.5 L

36
Q

what stimulates short chain FA production in calves?

A

starter

37
Q

what stimulates rumen development in calves?

A

low quality forage

38
Q

what is the cutoff brix value % that would indicate failure of passive transfer?

A

8.1%

39
Q

what is 1 negative outcome of pasteurizing colostrum

A

kills all bacteria

40
Q

classification looks at genetics not

A

performance

41
Q

4 things holstein canada does

A

1) identification & registration
2) genotyping
3) classification & assessment
4) field service

42
Q

purpose of classification assessments

A

to increase genotypic reliability

43
Q

why does classification not take into account milk traits?

A

bc of diff environments

44
Q

what lactations are peak productivity

A

3, 4 & 5

45
Q

what does classification do?

A

improve herds from a conformational standpoint

46
Q

what makes a good silage

A
  • plant maturity
  • particle size (pack it down so no O2)
  • lactic acid fermentation
47
Q

silaging process

A

harvest -> cut -> fermentation -> cover

48
Q

fermentation of silage will stop after how many days

A

10

49
Q

why do we cut a silage face flat?

A

to minimize surface area in contact with air

50
Q

substrate for lactic acid fermentation

A

water soluble carbs

ANSC 460 (16 decks)

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