Midterm 2: Dairy 1

Question 1

the average production per cow in canada is

Answer 1

10,675 L per lactation

Question 2

true or false: dairy cattle production systems need high quality forage

Answer 2

true! because they are producing so much milk they have very high requirements and require high quality feed

Question 3

colostrum is not only a source of antibodies, but also ____

Answer 3

essential nutirents like fats, proteins, vitamins, minerals, hormones, growth factors

Question 4

how is colostrum important for growth and development of the digestive tract?

Answer 4

the hormones and growth factors in the colostrum are necessary to stimulate growth and development of the digestive tract as well as other organ systems

Question 5

which has better colostrum: heifers or cows?

Answer 5

cows because they have more of a built immunity

Question 6

what is the target amount for serum IgG following colostrum ingestion for dairy calves? if they get less than this amount, what is it called?

Answer 6

10 mg/ml
if less than this, calf is considered t have failure of passive transfer

Question 7

true or false: failure of passive transfer reduces long term performance

Answer 7

true

Question 8

dairy calves need to be fed colostrum before _____ to acheive serum IgG levels above 10 mg/ml. How many grams on average do they consume in this time?

Answer 8

6 hours
80-100 g IgG to acheive at least 10 mg/ml

Question 9

how do you calculate colostrum required for a calf?

Answer 9

• use the calf body weight (example 40kg)
• the plasma amount is 9% of body weight, which would be 3.6 L (40 x 0.09=3.6)
• the minimun plasma oncentration we want is 10 g/L
• absroption is around 35%
• so if there’s 3.6 L of plasma in the calf, and we want 10g/L, so 3.6 x 10 /0.35 efficiency=103 grams
• concentration for IgG is 50 g/L, which gets you 2.1 L
  -required amount to feed is 2.1 L

Question 10

how do you measure colostrum quality?

Answer 10

colostrometer measuring density, refractometer measuring immunoglobulin concentration

Question 11

colostrum should contain a minimum of

Answer 11

50 mg/ml of IgG

Question 12

____ and ____ are important as immediate sources of energy to maintain body temperature, as calves are born with low energy reserves

Answer 12

fat, lactose

Question 13

what should you do if the colostrum is not good quality?

Answer 13

• colostrum can be stored frozen for more than 1 year, and can be thawed in warm water
• colostrum substitutes are available but not as good as actual colostrum

Question 14

since a calf is functionally a non-ruminant, they need to be fed

Answer 14

easily digestible CHOs, protein, and lipids

Question 15

after a dairy calf is given colostrum, what should they be fed?

Answer 15

milk or milk replacer until weaning

Question 16

what is “hospital” milk and why is it fed to calves? what are the risks of feeding it?

Answer 16

• it is milk either not suitable for shipping, mastitis milk, or milk with antibiotic residue
• it is “raw” milk, so there is a risk of infection
• some producers pasturize their hospital milk
• antibiotic residues can inhibit calf development of bacteria that normally populate the healthy gut
• can contribute to antibiotic resistance

Question 17

how do you tell if a milk replacer is good quality?

Answer 17

bad quality: vegetable proteins and fats
good quality: animal fats blended with emulsifier like whey, whey protein concentrate, also you need vitamins, minerals, and amino acids

Question 18

why are B complex vitamins necessary in milk replacer diets?

Answer 18

they are young calves, non ruminants, so the microflora cannot produce vitamin B yet! so it must be supplemented until rumen fermentation is active

Question 19

when does the calf rumen start to develop? by what time is the rumen fully developed (usually)?

Answer 19

as soon as the calf starts to eat dry feed
6 to 8 weeks should be fully developed

Question 20

how much do we want the calves to gow before weaning? why is this?

Answer 20

goal is to double the calf birth weight at weaning, because:
- makes it easier to hit breeding weight at earlier age
- reduce age at first calving
- reduce production costs

Question 21

calf starter should contain ____% crude protein

Answer 21

20-22

Question 22

what should the protein quality be in a calf starter? what is a common choice?

Answer 22

should be high quality because the rumen is only just starting to become functional. common choice is soybean meal due to good balance of amino acids and it’s palatability

Question 23

true or false: calf starter should not contain a coccidiostat

Answer 23

false! it should! example is rumensin

Question 24

how long is calf starter fed?

Answer 24

until the calf is consuming 2kg per day

Question 25

what is an accelerated calf feeding program?

Answer 25

when you give calves milk replacer with higher protein concentration and calves are fed twice as much milk replacer per day, leading to higher growth rates before weaning. It is not for everyon and the benefits should be calculated before implementing it since it is expensive

Question 26

true or false: calves are born with limited energy reserves and only modest insulation afforded by hair coat and body fat

Answer 26

true! if it’s cold, extra feed should be given to compensate/meet requirements

Question 27

what is the objective of feeding calves from weaning to breeding?

Answer 27

to feed heifers to atten a pre selected or target weight at a given age to acheive optimum first lactation performance while controlling the costs of rearing replacements

Question 28

from the period between weaning and breeding of dairy calves, what can happen if there is excessive energy intake?

Answer 28

it can have negative effects on mammary development by affecting the mammary parenchyma, and subsequent over conditioning can reduce first lactation milk production

Question 29

dairy heifers reach puberty at about

Answer 29

55% of mature body weight

Question 30

,after weaning, what is a dairy calf fed?

Answer 30

you can continute to give them the starter and then start offering high quality hay immediately after weaning, called a grower ration

Question 31

a grower ration is what % CP?

Answer 31

16-18

Question 32

a grower ration can replace starter feed when…

Answer 32

calves are around 4 months old and eating 2kg of starter per day

Question 33

when can heifers be moved to a silage based TMR from the grower ration?

Answer 33

at around 6 mnths of age

Question 34

what is mature shrunk body weight (MSBW)?

Answer 34

weight of a cow after she delivers her third calf and following an overnight fast without feed or water

Question 35

how many calves does a cow need to have in order for the body weight to be 100% of MSBW?

Answer 35

3

Question 36

what % of mature shrunk body weight is:
- first bred target BW
- first post calving target BW
- second post calving target BW
- third post calving target BW

Answer 36

• 55%
• 82%
• 92%
• 100%

Question 37

when does a dairy replacement heifer normally reach puberty

Answer 37

9-10 months

Question 38

dairy heifers should be kept at what BCS?

Answer 38

3 to 3.5

Question 39

if everything works out, at what age should heifers be calving for the first time?

Answer 39

23 months

Question 40

for the first 2/3 of pregnancy, nutrient requirements are to support…

Answer 40

maintenance and continuing growth only

Question 41

during the last trimester of pregnancy, nutrient requirements change how?

Answer 41

they increase significantly due to the rapid growth of the fetus and associated tissue

Question 42

at around _____ pre calving, pregnant heifers should be moved to a higher energy close up diet, which is similar to ingredients to the diet fed after calving.

Answer 42

3 weeks

Question 43

why are pregnant heifers close to the time of calving moved to a higher energy diet? during this period, should heifers be kept with dry cows?

Answer 43

to promote rumen microbial adaptation
heifers should be kept separate from dry cows to prevent competition, older animals are dominant and can restrict feed intake of younger ones