Dairy 2 Flashcards
***emphasized in class*** material from dry period onwards.
what is the dry period in cattle? give length and what happens to mammary gland
period between end of one lactation and beginning of next [this will be before parturition]. mammary gland is involuting during first 5 weeks. total length is 50-60 days
what is the 2 group nutritional scheme for dry period
in the 2 group scheme, diet 1 has lower Mcal/kg and is fed until 21 days before parturition. diet 2, the last 21 days before birth, has higher Cal/kg
give at least 3 reasons why transition period in dairy cows is a critical time of life
many physiological and metabolic changes (from pregnant nonlactating to non pregnant lactating), most health disorders occur during this time, most infectious diseases occur during this time (eg. milk fever, ketosis, immunosuppression mastitis), important for health and production of the animals
definition of transition period in dairy cows
period between 3 weeks before and 3 weeks after parturition
in the dry period, what is happening to the rumen
adaptation of rumen microbiota to digest higher starch diet, adaptation of epithelium and papillae to absorb large amount FVAs produced by fermentation, size of luminal papillae are decreasing and then 2 weeks pre-parturition begin increasing
during the transition period nutrient requirements are __ and DMI is ___ (at least until birth)
increasing, decreasing (after birth, DMI increases)
what is linked with greater incidences of periparturient health problems
excessive lipid mobilization from adipose tissue
DMI increases or decreases as calving approaches during transition period of dairy cows
decreases
how does body condition target score change from calving day to dry period
calving day target BCS is 3.25-3.75, this drops to a low of 2.25-2.75 at 75 days post calving (while they are in negative energy balance), then increases back to 3.25-3.75 by beginning of dry period.
with short dry periods (under 30 days) or no dry period, cows may have ____
lower chance of somatic cell count reduction due to self-cure or cure achieved with dry cow antibiotics
what are 3 benefits of shortened dry periods (28-40 days)
allow 1-group nutritional scheme, can be used for multiparous cows to extend lactation period, and simplifies nutritional management of farm
describe high-fibre controlled energy dry cow feeding “Goldilocks diet”
provides just enough energy to cow, lots of chopped straw, includes ingredients of lactation diet, forage NDF is 40-50% of DM, fed as TMR, may need to add water
objectives of well balanced early lactation diets
maximize DMI, supply minimum requirement of fibre and protein, maximize diet energy availability, balance protein and carbohydrate fractions, meet all nutritional needs, prevent loss BCS and maximize milk production
heifers have a higher %DMI (by BW) compared to cows in the 3 weeks before calving, true or false
heifers have lower DMI compared to cows. (both cows and heifers are decreasing their DMI intake in the 3 weeks before calving)
in an obese cow, there will be a larger and more problematic reduction in DMI in the 3 weeks approaching calving, true or false
true
why do we even bother maintaining rumen fill during dry period of cow? give at least 2 reasons
decreases assisted calving, milk fever, retained placenta, displaced abomasum, and ketosis
give 5 parameters that should be monitored in early lactation
intake, poops (consistency, presence of grind. and finer particles), milk fat concentration, milk solids (higher protein than fat is not good), BCS
as milk production increases (kg/d), BW loss ____
also increases (higher negative energy balance)
Bertha the cow has went from BCS 3.75 to 2.75 from day 0 to 30 postpartum. should we be concerned she has lost this much body condition?
as long as we limit the BCS change to more than -1.25, and her lowest BCS is above 2.25, it is ok (negative energy balance is normal during this time)
at 4 days postpartum (very early lactation period), cows are consuming _____ net energy and metabolizable protein than is required to maintain a) neutral energy balance? b) demands of mammary use
a) less net energy and metabolizable protein that is required to maintain neutral energy balance (ie. they are in negative energy balance). b) enough for mammary use
what is the length of the net energy balance in cow location period? when is it most severe? what do we need to pay careful attention to during this time?
45-50 days; most severe first 3 weeks postpartum; monitor BCS
cows need nutrients for maintenance, lactation, growth, and gestation during their lactation period. the nutrient requirements of lactating cows vary according to what 6 factors
parity, cow size, body condition, milk production, physical activity/temperature, gestation/fetal growth
how is water lost from Bessie the cow
milk production, urine excretion, fecal excretion, sweat, vapour loss from lungs
what sources of water does Bessie the cow have
drinking/free water intake, ingestion in feed, water produced by body metabolism of nutrients
did you know, cows drink several times a day, up to 150 L/day and 4-15 kg/minute. water intake is increased by what 5 factors?
milk production, diet DM, diet salt content, exposure to direct sunlight, high temperature (drink 29% more at 30C compared to 18C)
water availability and quality are important for animal health and productivity. how much salt should be in good water
under 100 mg/L total soluble salts (TSS)
deficiencies in trace elements and vitamins, especially Se and vitamin E, may be associated with what
increased reproductive disease
rumen microbes make what vitamins
vitamin K and all B vitamins, as long as the rumens are healthy (if stressed may need added B3 (niacin) and thiamine (B1); minerals and vitamins are supplemented in feed as well)
what is net energy for maintenance in a 650 kg cow
NE maintenance per day = 0.080 Mcal/kg x BW^0.75 = 0.080 Mcal/kg x 650^0.75 = 10.3 Mcal/d
what is net energy for maintenance? what is NE for lactation in a 650 kg cow who produced 10 kg milk?
energy contained in milk produced.
the true formula is NEL (Mcal/kg) = (0.0929 x fat%) +( 0.0547 x CP%) + (0.0395 x lactose%).
the shortcut is 0.68 Mcal/kg milk, so about 6.8 Mcal/10 L.
I don’t know if we need to know the long formula. (also the cow weight doesn’t matter, I was being tricky)
what is the effect on NE lactation as: milk CP% increases? milk fat % increases? milk lactate % increases?
these all increase the net energy for lactation
for every 10 degree C reduction in ambient temperature below 20 degrees C, what is the effect?
1.8% reduction in DM digestibility for lactating cows (increases DMI which increases rate of passage of feed through digestive tract)
mild to severe heat stress have what affect on maintenance requirements?
increase (estimated by 7-25%, which is not great because DMI is reduces by heat stress. note heat stress is affected by ambient temperature, relative humidity, radiant energy, and wind speed)
primary goal of any nutrition program is
formulate diets that meet nutrition requirements of animal
what 2 things are needed as a major factor influencing nutrient utilization, to design an effective nutritional program for lactating dairy cows
DMI (the most important) and nutrient digestibility
what is DMI driven by in lactating dairy cows? does DMI increase increase or decrease digestibility of nutrients?
milk production. DMI increase (eg. due to increased milk production)–> faster passage rate of ingest –> decrease digestibility of nutrients
give the DMI (kg/d) in a cow with 4% fat corrected milk (FCM), 600 kg body weight (BW), at 4th week of lactation WOL).
DMI (kg/d) = [0.372 x FCM + 0.0968 x BW^0.75] x [1-e^(-0.192 x (WOL + 3.67)] = [0.372 x 0.04 + 0.0968 x 600^0.75] x [1-e^(-0.192 x (4 + 3.67)] = 9.06 kg/d. (note: there’s no sample calculation so I don’t know if this is right. also you are adjusting as needed in practice)
give the super approximate DMI, BW, milk production, %CP, %NDF, %starch, and %fatty acids for cows in Michigan, Ohio, Georgia study
23 kg/d DMI, 669 kg BW, 38 kg/d milk, 17% CP, 31% NDF, 27% starch, 2.6% fatty acids (I really don’t know what we’re expected to memorize, sorry)
as DMI increases, dry matter digestibility decreases according to the model formula DMD = 69 - 0.83 x DMI%BW.. the model works well for Ohio cows (midwestern USA) but not Georgia (southern USA). why?
the model works better for cooler areas. Georgia’s a warm state
as forage fibre increases in the diet, what happens to DMI
reduces DMI (note if there is too little fibre, adding fibre will help DMI, ie. increasing 20-25%. but then decreasing when cow is fed feasible rations of 25%-45%)
as NDF (as % of DM) increases in diet, what happens to DMI? what happens to fill limitation?
as NDF intake increases, max DMI increases, but fill limitation value decreases (say you fed 30% NDF to a cow, its fill limitation is at 4%, but it will only eat 2.75% DMI (for this particular cow). if you increase to 40% NDF, its fill limitation is now decreased to 3% but its DMI has increased to 3%)
optimum NDF intake occurs at
point of maximum milk yield, usually about 1.25% BW per day for cows in mid to late lactation
are cows eating more or less at second lactation, compared to first
more
pectins, hemicellulose, lignins, and cellulose make up cell walls. which are part of NDF? which are part of ADF?
hemicellulose, legnini, and cellulose are part of NDF (non-digestible fibre) (lignin is a non-fibre carbohydrate). only lignins and cellulose are ADF (acid detergent fibre)
what is formula for NFC (non fibre carbohydrate)?
NFC = 100% - CP% - NDF% - EE (ether extract) - ash
the volatile fatty acids ____ and ___ are used to produce triglycerides, responsible for milk fat. ____ is used to produce glucose and lactose, responsible for milk yield
acetate and butyrate; propionate
as the concentrates in diet increase and forages decrease, milk production _____
increases until 70:30 concentrate:forage ratio, at which point it plummets
as the concentrates in diet increase and forages decrease, milk fat _____
remains steady until 70:30 concentrate:forage ratio, at which point it decreases
as the concentrates in diet increase and forages decrease, what happens to total VFA production, propionic acid production, acetic acid production, and butyric acid production
total VFA production and propionic acid production increase until concentrates exceed 70% of diet, at which point they decrease. acetic acid produced decreases. butyric acid remains the same
as milk fat production increases, luminal pH
increases (more alkaline)
which ferment the fastest in the rune: pectin, soluble carbohydrates,or cellulose
soluble carbohydrates fastes (cellulose slowest)
order these processed corn grains from lowest to highest total digestible nutrients (TDN): ground, high-moisure, steam-flaked, and cracked
cracked, ground, high-moisture, steam-flaked (these are increasing rate of fermentation, so could influence risk of acidosis)
as minimum forage NDF decreases, minimum dietary NDF _____, maximum dietary NFC ________, and the minimum dietary ADF ________
minimum dietary NDF increases (need to get from a source other than forage), maximum dietary NFC decreases, minimum dietary ADF increases
NDF concentration in the diet must be higher when forage is _________
finely chopped
consider these 6 things when formulating diets at minimum concentration of NDF
base on composition of feed (not table values), particle size >3mm, grain source processing, feed as TMR, careful of feed mixing and delivery errors, and that it is better not to feed at the minimum NDF level
what is effective NDF, eNDF
sum total ability of NDF in feed to replace NDF if forage or roughage so that %milk fat is maintained
most sources of NDF from nonforage (eg. NDF from beet pulp or grain, rather than long coarsely chopped NDF) is significantly less effective at ____ than are forages
maintaining milk fat % (on average, non forage eNDF is only half was effective as NDF from forage, but listed cottonseed is an exception and has higher eNDF value than other non forages)
what is peNDF (physically effective peNDF)
physical characteristics of NDF, especially particle size, that affect chewing activity and biphasic nature (gas and liquid) or rumen contents
peak microbial protein production is about 4 kg/d. this will occur at what value of organic matter fermented in rumen per day?
25 kg/d (as organic matter in rumen increases, so does the microbial protein production, until that peak value. then after that drops off slightly)
pef should be _______ of ration DM for lactating dairy cows
> 21-22%
why do we need a minimum NDF
rumen health
why do we need a minimum NFC
for rumen fermentation (VFA and microbial protein synthesis) as well as for milk yield and protein. so, NFC is needed to supply energy to animal as well as the rumen microbiota
availability of carbohydrates with fast degradation in the rumen, ie. NFC, will have what effects on microbes and the animal
increase microbial protein synthesis as well as increase supply of metabolizable protein to animal
how does decreasing NFC in diet decrease milk protein production
decreased NFC –> decrease microbial protein synthesis –> decrease metabolizable protein supply –> decrease milk protein production
what is optimum NFC in dairy cow diet
38-40% DM
**an excess of NFC in dairy cow diet will have what effects? **
decrease ruminal pH, promoting subclinical or clinical acidosis, decreasing the milk yield and fat content
**an excess of NFC in dairy cow diet will have what effects? **
decrease ruminal pH, promoting subclinical or clinical acidosis, decreasing the milk yield and fat content
what should dairy cow poop look like
formed shape, see concentric rings
what should dairy cow feed look like
variety of particle sizes, the long fibres shouldn’t be super long or the cows will sort through them and not eat them
what is metabolizable protein?
true protein that is digested postruminally and the component amino acids absorbed by the small intestine.
ie. microbial protein + rumen undegradable protein + endogenous protein = metabolizable protein
how much protein does the dairy cow need? when does maximal microbial protein synthesis occur?
maximum microbial protein synthesis at 22 mg ammonium per decilitre of fumes fluid. MINIMUM level is 5 mg N-NH3/dl in rumen fluid, about 7% CP, but want more than this ideally
who will produce the most microbial protein (in kg/d): a dry cow, a cow producing 50L milk/d, or a cow producing 10 L milk/d
more milk = more microbial protein production. dry cows produce very little
which NFC type promotes higher efficiency of luminal microbial protein synthesis, NDF or starch?
starch
what are main 3 limiting amino acids in lactating cows?
methionine, lysine, histamine
when is methionine limiting amino acid in dairy cows
when majority of the rumen undegraded protein is supplied by oilseed meal (eg. soybean or canola meal) or animal protein
when is lysine limiting amino acid in dairy cows
when majority of the rumen undegraded protein is supplied by corn product
when is histamine limiting amino acid in dairy cows
when grass, barley, or oat silage is in diet
why should we avoid feeding excess protein in diet
energy intensive to convert to urea. (if we increase 4 mg/dl plasma urea N, corresponding loss of 200g of body fa or 1.5 L of milk. N is expensive to convert to urea). also negative effect on reproduction.
protein: what crude protein (CP) level do we aim for? how much of this CP should be rumen degradable vs undegradable protein (RDP vs RUP)?
16-17% CP. 60-65% of CP should be RDP, 35-40% of CP should be RUP
we monitor protein levels in dairy cattle with what biochemical parameter? what level do we aim for?
milk urea nitrogen (MUN) should be 12-18 mg/dl. milk protein also needs to be >3.2%
diets with excess CP (>19%) have a negative effect on reproduction. give a few specific negative effects related to reproduction (or other negative effects).
increase blood urea, decrease uterine pH, chance uterine fluid composition, decrease plasma progesterone decrease conception rate, increase services per pregnancy, increase days open, increase embryonic loss
give 4 benefits of fat supplementation
increase energy density, reduce heat increment, increase feed efficiency, decrease methane production
give 2 drawbacks of excess fat supplementation
decrease rumen fermentable matter, decrease fibre degradation in rumen (especially with unsaturated fats), reduce milk fat percentage through altering fermentation
how much fat to give in diet of lactating dairy cow
3-4% DM as supplemental fat; 6-7 ether extract in total diet DM
what is TMR? give an advantage of using TMR
most dairy herds are fed this diet type. every bite is a complete, nutritionally balanced diet. make milk fat depression and other digestive upsets less likely to occur
compare and contrast using a single-ration TMR vs several TMR-rations for a herd
single ration: simpler, formulated for needs of higher producing group (could lead to over conditioning of lower need groups), based on principle that higher needs cows will have higher DMI. multiple rations: can meet needs of different groups, reduces feed costs, and easier to control BCS, but requires moving animals (can cause stress) as their needs chance
give two ways concentrate amounts can be fed to lactating dairy cows
tie-stall and stanchion barns (these involve manually dispensing the concentrate on top of the TMR) vs free-stall barns with a computerized concentrate feeder (program the allowances of feed)
what is a potentially disadvantage of using concentrate as a motivating factor for cows to enter the robotic milking system
diet consumed may be different from what is formulated (1 kg of dispensed feed may replace 0.8-1.6 kg of the partial mixed ration, ie cows not eating to their needs)
when there is a sudden increase in Ca demand from late gestation to early lactation, what disease can occur? give subclinical and clinical indicator (hint: give the blood value)
hypocalcemia (milk fever), a decrease in plasma Ca concentration. subclinical is total blood Ca 1.4-2.0 mol/L; clinical is <1.4 mmol/L
subclinical hypocalcemia has what 4 negative effects on dairy cows
increase risk of metabolic and infectious disease, increase risk of reproductive disorders, increase early culling, decrease milk production
calcium homeostasis: alkaline blood causes a conformational change in PTH receptors, causing what
loss of tissue sensitivity to PTH
calcium homeostasis: hypomagnesia causes loss of tissue sensitivity to what
PTH
what breed and age is most susceptible to hypocalcemia
older cows > heifers (heifer bones are more responsive to PTH and more receptors for vitamin D in intestine); Jersey cows more susceptible
give 2 diet strategies to prevent hypocalcemia
low Ca diets or low dietary cation-anion diets
excessive dietary intake of P increases the risk of what
hypocalcemia
low plasma calcium stimulates ___ release, which acts to resorb calcium from bone and ____ renal absorption of Ca
PTH (parathyroid hormone); enhance
high plasma calcium stimulates _____ secretion which lowers plasma calcium by limiting _______
calcitonin; bone resorption
parathyroid hormone has what 2 functions
raise calcium via bone resorption and renal calcium reabsorption; stimulate vitamin D production by kidney
prepartum dairy cow diets should be balanced for what 3 nutrients and 1 other factor to reduce the risk of hypocalcemia
Ca, Mg, P intake; dietary cation-anion diet value (details: Ca intake 50-70g/d; Mg 40-50 g/d; P <35/d; DCAD -150 to 150 mEq kg/DM
diet DCAD should be adjusted to achieve average urinary pH of what in Holstein cows? what about Jersey cows?
6.0-7.0 for Holsteins, 5.5-6.5 for Jerseys (think, Jersey cows are little, so they have a little lower pH)
ketosis, which a majority of high-producing cows are likely to experience to some degree subclinically in early lactation, can occur is negative energy balance state due to ______
excessive fat mobilization (end-products of liver fat metabolism are ketone bodies)
how can ketosis be detected
blood, milk, urine, and smelling cow breath (sweet breath)
how can ketosis be detected
blood, milk, urine, and smelling cow breath (sweet breath)
you cow is off feed, constipated, depressed, loses some BCS, and is producing less milk. you smell her sweet breath and grab a confirmatory test and some treatment for her condition. how are you treating her condition
propylene glycol is preferred treatment, IV glucose may have some immediate benefit
_________ administration to close-up dry cows reduces the incidence of ketosis
monensisn sodium
you cow is off feed, constipated, depressed, loses some BCS, and is producing less milk. you smell her sweet breath and scribble the disorder you suspect on your SOAP, which is ______
ketosis
most LDAs are diagnosed during what stage of a cow’s life
first 2 weeks postpartum
the abomasum can rotate under the rumen and omasum to the left or right, but usually rotates to the ___ side
left (90% cases)
when excess gas collects in the abomasum and rotates under the rumen and then up on the left side of the body behind the rumen (which is emptier than usually due to decreased feed intake), this is known as ______ and surgical intervention may be required
left displaced abomasum
how can LDAs be prevented, give at least 3 ways
prevent decrease in DM intake prevent hypocalcemia, promote adequate rumen fill, manage BCS
what is the most common metabolic disorder in dairy cattle? give term and explain the condition
subacute rumen acidosis = pH of rumen between 5.2 and 5.6 for at least 3 hours in a day
define rumen acidosis, including clinical signs
rumen pH below 5.0; this is less common but more serious than subacute rumen acidosis; causes elevated HR, diarrhea, depression, potential death if untreated
what are at least 3 possible causes of rumen acidosis
decreased VFA production reducing absorption and buffering; excess grain or NFC in diet; rapid increase in dietary NFC, highly fermentable forages and/or insufficient dietary coarse fibre; insufficient rumen buffering due to inadequate chewing and salivation, cows sorting forage from diet
incidence of subacute rumen acidosis is _______ in early and mid lactation dairy cow
19-26%
give at least 4 consequences of subacute rumen acidosis
feed intake depression, reduced fibre digestion, milk fat depression, diarrhea, laminitis, liver abscesses, increased production bacterial endotoxin, inflammation
high levels of non-esterified fatty acids (NEFA) indicate a state of ne
low levels of beta-hydroxy butyrate are acceptable during period of negative energy balance in dairy cows (small amount of body weight loss is acceptable). at what level of BHBA is excessive, indicating that the degree negative energy balance is too large?
> 1 mmol/L
nonesterified fatty acid (NEFA) level limits are _____ prepartum and ___ postpartum
0.29 mmol/L prepartum and 0.57 mmol/L postpartum (it is normal to have some degree of negative energy balance postpartum; these are the limits)
