Dairy Nutrition Flashcards
what state ranks 1st in dairy cow inventory
california
where does Texas rank in terms of dairy cattle inventory
4th
what percent of total US dairy inventory does Texas hold
6.8%
trend of average dairy herd size and number of herds
size has increased and number has decreased
what are NE values affected by
-nutrition composition of feeds
-physiological function of animal
how does nutritional composition of feed affect NE
fiber has higher heat increment
which has a higher heat increment: growth or lactation
growth
T/F NE for lactation will always be higher? why/why not?
TRUE, heat increment is low
equation for NE
NE = ME- HI
T/F lactating cattle are less efficient than growing cattle
FALSE. they are more efficient
why is it impossible to meet lactating cows nutrient demands
demands exceed DMI
how do dairy cows meet nutrient requirements when feed doesnt
mobilization of fat
dairy cow production phases
- early lactation
- mid lactation
- late lactation
- dry period
- transition period
early lactation characteristics
-0-10 wks
-peak milk production at 3-6 wks
mid lactation characteristics
-10-24 wks
-milk yield begins to decrease
-peak DMI at 11-13wks
late lactation characteristics
- > 24 wks
-decreased milk yield
-cow regains body tissue reserves
dry period characteristics
-5-8 wks
-late pregnancy
transition period characteristics
-2-3 wks
-late pregnancy
-prepare for lactation
how does lactation rank in physiological priority throughout milking phases
Early: highest priority
Middle: 2nd(behind repro)
Late: lowest(repro, growth, maintenance)
issue with feeding high grain diets to dairy cows
damage to rumen papillae and depress milk fat
milk fat thresholds for $/cwt increase
.1% above 3.2%
bonus .1% over 3.5%
what factors are producers paid based on
milk volume
milk composition
milk quality
what threshold of milk quality are producers paid extra
$.03 per 20,000?l below somatic cell count of 400,000/L
how does rumination affect digestion
salivation increases rumen pH, increased pH is favorable for fiber loving microbes
why is the acetate:propionate ratio important
acetate helps with milk fat production
what rumen pH does acetate prefer
higher pH
what rumen pH does propionate prefer
lower pH
rule of thumb for adequate fiber levels
-forage:concentrate ration of 40:60
-minimum 21% ADF
-minimum 1-1.5% BW as forrage
what is effective fiber dependent on
-particle size(larger=effective)
-amount of chemical fiber(CF, ADF, NDF)
-type of fiber(amount lignin)
how does effective fiber affect rumination
increased effective fiber increases rumination
how does the roughage index value effective fiber
measures amount of time cow spends ruminating(calculated as minutes chewing per unit DM)
methods to measure effective fiber
-roughage value index
-particle size separator
-sensor technologies
how does the particle size separator measure effective fiber
sorts into large, medium, and small
large:6-10%
medium:30-50%
small:40-60%
how do sensor technologies measure effective fiber
collar monitors rumination
what reproduction phase will the cow have a drop in feed intake
a few days before calving
short term benefits of proper fiber
increased milk fat synthesis
long term benefits of proper fiber
prevent acidosis and rumen burnout
nutritional factors(other than fiber) that affect milk composition, and how?
-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
grain rates of fermentation(fastest to slowest)
Fastest: Wheat
Barley
Slower: Milo, Corn
situations where dairy buffers are beneficial
high corn-silage diets
high grain diets
low effective fiber diets
cows off feed(early lactation)
what and how much buffer can be fed to cows
sodium bicarbonate @ 1% of DM
how much fat can you add to cattle diet
5%, most feeds contain 3% fat
issues with adding more than the acceptable amount of fat to the diet
-decreased feed intake
-decreased fiber digestion
-increased digestive upset
how much fat is acceptable in cow diets
8%
benefits of adding fat to dairy cows
-increased milk production
-less weight loss
-less impacted by heat stress
-decreased heat increment
-reduce ketosis
-enhance reproductive performance
cheapest fat sources
plant seed oils
most expensive fat sources
processed fat sources
mid range fat sources
unprocessed fat
purpose of bypass fats
dont disrupt rumen fermentation of fiber
feeding systems for lactating dairy cows
Traditional
TMR
disadvantages of traditional feeding system
estimating forage DMI and nutritional quality makes it difficult
what is the traditional feeding system
forage and concentrates fed separately
what is Total mixed ration feeding system
forages and concentrates mixed together
disadvantages of TMR
all forages must be harvested
advantages of TMR
-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
advantages of traditional feeding system
-no need for harvesting forages
-equipment is less expensive
new method for preventing milk fever
dietary cation-anion balance(DCAB)
how does DCAB work
negative DCAB before calving lowers milk fever(feed negative balance during stage 5)
cation(alkalogenic) macrominerals
Na and K
anion(acidogenic) macrominerals
Cl and S
what is the recommended DCAB
-10 to -15 meq/100 g diet DM
challenges to feeding negative DCAB
-anion salts are more expensive
-anion slats are less palatable
symptoms of ketosis
-elevated ketone bodies
-depressed blood glucose levels
-decreased appetite
-decreased milk production
-distinctive acetone
T/F ketosis is very deadly to dairy cattle
FALSE. cows rarely die from it
occurrence of ketosis
-2-15% get clinical ketosis
-50% get borderline ketosis
-most cases occur within 60 days of calving
prevention of ketosis
-avoid excess BCS at calving
-good transition diet
-maximize DMI during early lactation
-feed glucose precursors
-feed niacin(b-complex vitamin)
