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
