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Final Exam - Dr. Kenyon
Terms in this set (96)
What is the average weight of a mature Holstein cow?
What % of her body weight will a dairy cow consume (dry matter intake) at mid lactation?
On average, how many lbs of milk will a dairy cow produce a day?
120-140lbs or about 14 gal
What are the most important breeds of dairies in the USA, Canada, and Europe?
Holsteins and Friesians
Which dairy breed is prone to hypocalcemia at calving?
Which breed of dairy cows is susceptible to Johnes Disease?
Which breeds of dairy cows are the channel island breeds?
Jerseys and Guernseys
What are some disadvantages to Holstein milk?
protein and fat are only moderate
Which dairy breeds produce milk high in protein and fat?
Jerseys, Guernseys, and the Brown Swiss
In which dairy breed are the bulls dangerous and should never be trusted?
What size pieces of fiber do ruminants need to produce the rumen mat?
greater than 1 cm
What fiber feeds form the bulk of dairy rations? What 2 advantages to these feeds.
alfalfa, grass, hay, and corn silage; they are cheap and produce a large tonnage of feed per acre
Why must you feed dairy cows more than just forages?
they are high producing and forages alone are too bulky, they cannot eat enough of them to meet their protein and energy requirements
What is the most common energy supplement for dairy cows? the most common protein supplement?
corn grain; soybean meal
What is pasture dairying?
intensely managed grass and legumes as the main feed source, with cows being moved to fresh paddocks, or having new parts of the field opened for grazing twice a day. supplemental grains and minerals are fed to cows in the milking parlor
How is the nutrient value of pasture maintained for pasture dairying?
by grazing or mowing it intensively enough that it is maintained in a vegetative state
When are dairy calves removed from the dam?
How are calves housed?
ideally in individual hutches until they are weaned at about 6 weeks, group housed until the are 6 months, then turned out to pasture
What are heifers?
cows from 6 months of age to their first calving
At what age is a heifer first bred? When will they have their first calf?
15 months; 24 months
What is unique about first lactation cows, or first calf heifers?
they are still growing during their first lactation and therefore have different nutrient requirements
What is the transition period?
from 2 weeks before calving to 3 weeks after calving
What is a "fresh cow"?
a cow that has recently calved
When do most metabolic diseases, lameness, and new infections occur in dairies?
the transition period
When do cows reach peak milk production? When do they reach peak appetite?
4-6 weeks after calving; 8-11 weeks after calving
How much weight is a 1300lb dairy cow expected to loose during peak lactation?
Why do we BCS cows during their dry period?
to make sure they have enough fat reserves for early lactation
When do you stop milking a cow? How are they dried off?
60 days before they have their next calf; not milking them and restricting food intake
How many days into lactation should a cow become pregnant?
How long is gestation in dairy cows?
280 days, or 13.2 months
What is the voluntary wait period?
the 60 days after calving that the farmer waits before trying to breed the cow again
How often to cows come into estrus?
every 21 days
Cows are synchronous feeders. What does this mean?
they like to eat together as a group. when one cow gets up to go feed, they all will
What is an ideal amount of space each cow should have at the feed bunk?
Name 7 problems that can occur from an overcrowded feed bunk.
1) aggressive interactions increase
2) shorter eating times
3) eat faster
4) eat at night more often
5) low social ranked cows lie down when food is put out
6) standing time increases
7) rumination decreases
Name 2 ways to increase dry matter intake.
1) increase times feed is put out per day
2) push feed up to cows between feedings
What is the primary driver of dry matter intake? in practice, what is the energy driver?
energy demand; stage of lactation
What is the effect of feeding highly digestible feed?
dry matter intake increases
On many dairies, what is most of the fiber component supplied by?
Name 4 things that interfere with dry matter intake.
1) rumen acidosis/indigestion
2) heat stress
3) crowding and competition
4) restricted water intake
What has very little nutrient requirement but is a very good source of effective fiber?
Why have bunker silos and agbags become more popular than upright silos?
longer silage cannot pack well in uprights leading to poor fermentation and longer silage is more difficult to unload and can burn out the unloader's motor
Why is effective fiber important?
it contributes to rumination and cud chewing
Why is cud chewing important?
it results in secretion of large amounts of bicarb in saliva which buffers the rumen pH and prevents rumen acidosis
What effect does the rumen mat have on feed particles?
it slows their passage from the rumen to the abomasum
What is a sign of reduced digestive tract passage time and sub-acute rumen acidosis?
pale, loose manure, with feed particles and bubbles
What is a good rumen pH?
What do high grain diets lead to?
excessive VFA production
What does insufficient effective fiber reduce?
salivary production of buffer
How many lbs of water do cows require for every lb of milk production?
3lbs water/1lb milk
When will cows drink most of their daily water requirement?
just after milking (about 60% of their daily requirement)
Cows prefer their water slightly warm. How do we accomplish this?
we use the warmed water from the plate cooler that pre-chills the milk on the way to the bulk milk tank
How many water sources should be provided in the cow housing area?
What type of waterer do cows drink best from?
an open surface such as a trough
What are the cows 3 main sources of energy?
1) structural carbs (cellulose and hemicellulose)
2) cell cytoplasm (sugars, starches, etc)
3) fat, but not in the rumen (body reserves)
What is NDF used as a measure of?
effective fiber (high NDF means a woody, indigestible stem)
What is ADF used as a measure of?
energy value (low ADF, high digestibility and high energy)
What 3 VFAs are fibers and starches converted to in the rumen?
acetate, propionate, and butyrate
What does the cow get 50-70% of its energy from?
What are the 2 major fates of acetic acid?
used to make ATP and used as acetyl CoA for production of lipids
What is the major fate of propionic acid?
goes to the liver and is used in gluconeogenesis
What is the major fate of butyric acid?
oxidized for energy production
What is the common system used for measuring energy in the USA?
Net Energy System (NE)
When measuring energy, what does TDN not take into account?
energy lost in feces
What is the main source of protein for the ruminant?
What is Rumen Degradable Protein?
the intake protein that is degraded in the rumen and made into rumen bacteria
What is rumen by-pass protein, or Rumen Undegradable Protein?
intake protein that is not degraded by the rumen
Where are microbial protein and rumen undegradable protein digested?
What are the limiting amino acids for high producing cows?
lysine and methionine
Why are non-fiber carbohydrates important?
it is an important energy source for bacteria in making microbial protein
What % protein are dairy rations usually formulated at?
What are BUN and MUN and why are they monitored?
blood urea nitrogen and milk urea nitrogen; it measures the overall efficiency of protein utilization
What 3 things does feeding excess protein lead to?
1) elevated MUN, which leads to increased urinary excretion of nitrogen
2) increased hoof lameness
3) poor fertility
What 3 things may cause a high MUN?
1) high RDP intake
2) not enough rumen available energy
3) high levels of NPN or highly degradable protein
What 2 things might an MUN of 10mg/dL or less indicate?
1) not enough dietary crude protein
2) insufficient RDP
What is commonly substituted for corn to minimize rumen acidosis? What is a drawback of doing this?
fat; you are reducing energy available to bacteria and protein metabolism becomes less efficient
What are the 3 major minerals required in dairy nutrition?
calcium, magnesium, and phosphorus
Instead of feeding a Ca:P ratio, how are Ca and P best fed?
to meet requirements separately
High levels of waht mineral have been implicated in the pathogenesis of hypocalcemia?
Why are anionic salts such as NH4CL, HCl, and MgSO4 fed to dairy cows?
to acidify the interstitium of the cow and increase the pool of available Ca at calving
Why don't we feeed excess Ca at calving?
it reduces the availablity of a wide range of other minerals
Why would you add fats to a dairy ration instead of corn?
high levels or corn can cause rumen acidosis
What percent fat can a dairy ration before it starts to have palatability problems?
If fats are added to a dairy ration in place of starch, what problem does cause? How do we fix it?
ruminal bacteria cannot use fat instead of starch as an energy source, so we add RUP to the diet to make up for less efficient bacterial protein synthesis
As far as dry cow nutrition is concerned, what do the best feeding methods employ?
low energy, higher fiber
Why might you increase energy density in close-up cow rations?
this is based on the idea that the rumen bacteria need to be adapted to the high starch rations of the lactating cow
Why might you feed a ration of the same number of pounds of NDF to a close-up cow that a lactating cow would need (for example, feed 11lbs of straw)?
this is based on the theory that the bacteria need to have a high buffering capacity and be efficient at digesting fiber at calving
What are the 4 key principles of dairy nutrition?
1) maximize dry matter intake
2) maximize energy intake
3) preserve rumen health
4) protect the transition cow
What are the 2 rules of dairy nuttrition?
1) make more milk
2) reduce costs as long as it doesn't conflict with rule #1
What is the best life insurance for a dairy cow?
to be pregnant
When do cows do their best work?
The cows are producing 60lbs of milk a day, fertility is poor, MUN is high (about 18mh/dl), manure is loose and dark, and there are ketosis problems.
The ration is corn silage, very high quality alfalfa haylage, prime quality alfalfa hay, grain mix with corn, soybean meal and minerals. Crude protein is 16.5%
What do you do?
replace soybean meal with distillers grain
What is an open cow?
a non-pregnant milking cow
What is the ideal BCS for a close-up dry cow?
What % NDF is best for dairies?
What is normal rumen pH?
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