Midterm 2: Dairy 1 Flashcards
the average production per cow in canada is
10,675 L per lactation
true or false: dairy cattle production systems need high quality forage
true! because they are producing so much milk they have very high requirements and require high quality feed
colostrum is not only a source of antibodies, but also ____
essential nutirents like fats, proteins, vitamins, minerals, hormones, growth factors
how is colostrum important for growth and development of the digestive tract?
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
which has better colostrum: heifers or cows?
cows because they have more of a built immunity
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?
10 mg/ml
if less than this, calf is considered t have failure of passive transfer
true or false: failure of passive transfer reduces long term performance
true
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?
6 hours
80-100 g IgG to acheive at least 10 mg/ml
how do you calculate colostrum required for a calf?
- 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
how do you measure colostrum quality?
colostrometer measuring density, refractometer measuring immunoglobulin concentration
colostrum should contain a minimum of
50 mg/ml of IgG
____ and ____ are important as immediate sources of energy to maintain body temperature, as calves are born with low energy reserves
fat, lactose
what should you do if the colostrum is not good quality?
- 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
since a calf is functionally a non-ruminant, they need to be fed
easily digestible CHOs, protein, and lipids
after a dairy calf is given colostrum, what should they be fed?
milk or milk replacer until weaning
what is “hospital” milk and why is it fed to calves? what are the risks of feeding it?
- 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
how do you tell if a milk replacer is good quality?
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
why are B complex vitamins necessary in milk replacer diets?
they are young calves, non ruminants, so the microflora cannot produce vitamin B yet! so it must be supplemented until rumen fermentation is active
when does the calf rumen start to develop? by what time is the rumen fully developed (usually)?
as soon as the calf starts to eat dry feed
6 to 8 weeks should be fully developed
how much do we want the calves to gow before weaning? why is this?
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
calf starter should contain ____% crude protein
20-22
what should the protein quality be in a calf starter? what is a common choice?
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
true or false: calf starter should not contain a coccidiostat
false! it should! example is rumensin
how long is calf starter fed?
until the calf is consuming 2kg per day
what is an accelerated calf feeding program?
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
true or false: calves are born with limited energy reserves and only modest insulation afforded by hair coat and body fat
true! if it’s cold, extra feed should be given to compensate/meet requirements
what is the objective of feeding calves from weaning to breeding?
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
from the period between weaning and breeding of dairy calves, what can happen if there is excessive energy intake?
it can have negative effects on mammary development by affecting the mammary parenchyma, and subsequent over conditioning can reduce first lactation milk production
dairy heifers reach puberty at about
55% of mature body weight
,after weaning, what is a dairy calf fed?
you can continute to give them the starter and then start offering high quality hay immediately after weaning, called a grower ration
a grower ration is what % CP?
16-18
a grower ration can replace starter feed when…
calves are around 4 months old and eating 2kg of starter per day
when can heifers be moved to a silage based TMR from the grower ration?
at around 6 mnths of age
what is mature shrunk body weight (MSBW)?
weight of a cow after she delivers her third calf and following an overnight fast without feed or water
how many calves does a cow need to have in order for the body weight to be 100% of MSBW?
3
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
- 55%
- 82%
- 92%
- 100%
when does a dairy replacement heifer normally reach puberty
9-10 months
dairy heifers should be kept at what BCS?
3 to 3.5
if everything works out, at what age should heifers be calving for the first time?
23 months
for the first 2/3 of pregnancy, nutrient requirements are to support…
maintenance and continuing growth only
during the last trimester of pregnancy, nutrient requirements change how?
they increase significantly due to the rapid growth of the fetus and associated tissue
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.
3 weeks
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?
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
