Midterm 2: Dairy 2 Flashcards
what is the dry period? why is it important? What is the usual recommended length?
period between the end of one lactation and the beginning of the next. it allows the mammary gland to rest and it helps longevity of cows, and requirements are lower uring this time so you can rejuvenate the rumen by feeding a high forage diet
50-60 days usually
what does “preconditioning of the rumen” mean?
adaptation of the rumen from the dry period (mostly forage diet) back to a higher starch diet that will be given close to and after partuition, both the microbiota and the rumen epithelium need to adjust
what is the “transition period’? why is this a critical time in the dairy cows life?
the period between 3 weeks before to 3 weeks after partuition
- during this time the cow goes thru physiological and metabolic changes, transitioning from preg and non lactating to the non pregnant and lactating states. most health disorders occur occur during this time as well.
most infectious and metabolic disorders happen during what time in a dairy cows life? List some examples of such disorders
the transition period
ex: milk fever, ketosis, retained fetal membranes, metritis, displaced absomasum, immunosuppression–> mastitis
during the transition period, there is an increase in nutrient requirements, but what happens to DMI? What does this cause?
DMI decreases, cows are not eating as much.
Results in excessive lipid mobilization from adipose tissue which leads to many health problems
who has a more dramatic drop in DMI during the transition period, heifers or cows?
cows have a more severe drop than in heifers
what effect does body condition have on the drop in DMI during the transition period?
fatter cows have a more severe drop in DMI compared to moderate or thin cows. thin cows seem to handle the transition period better with a less dramatic drop, but we don’t want to keep cows too thin
true or false: short dry periods or no dry period may given a lower chance of SCC count reduction
true. for this reason we do not want short dry periods and we definitely don’t want to have no dry period at all
during the dry period, cows are fed a HFCE which stands for what? why are they fed in this manner?
high fiber controlled energy
the diet provides just enough energy to the cow (since requirements are lower uring this time), and usually contains large amounts of straw. idea is to maintain good rumen fill and prevent health problems
what are the objectives of diets in early lactation?
- to maximize DMI
- supply minimun fiber requirement
- supply the minimum requirements of protein
- maxmize diet energy availability
- balance protein and carbs
- prevent BCS loss
- maximize milk production
what parameters should be monitored in early lactation?
- intake, feces (whole pieces, consistency), fat concentration in milk, milk solids, BCS
what is usually the length of the negative energy balance?
45 to 50 days, more severe in the first 3 weeks post partum
loss of water from the body occurs how?
- milk production
- urine
- feces
- sweat
- vapor from lungs
water ______ and _____ are extremely important for animal health and productivity
availability, quality
how do you know water is good quality?
if it has less than 1000mg/L total soluble salts (TSS) in water
rumen microbes can make which 2 vitamins? what does this mean?
- K and B
- this mens most cattle with healthy rumens dont need added B or K vitamins
- however, cows under stress may need niacin and thiamine
deficiences in trace elements and vitamins, particularily _____ may be associated with increased reproductive disease
selenium and vitamin E
net energy maintenance = 0.080 Mcal/kg x BW^0.75
OBSERVE
net energy for lactation =
energy contained in the milk produced
what effect do low temperatures have on requirements for lactating cows?
it actually reduces digestibility, because cows will eat more (increase DMI), and this increases the rate of passage of feed through the digestive tract
what effect do high temperatures have on requirements for lactating cows?
heat increases maintenance requirements, and reduces DMI
in lactating dairy cows, DMI is driven by_______ and limited by _____
milk production, physical fill/metabolic effects
increased DMI increases ______ and thus depresses _____
increases passage rate of digesta and depresses digestibility of nutrients since the feed moves through faster
what is the connection between fiber and DMI?
when fiber increases, DMI decreases
DMI reduces with increasing forage fiber in the diet
the optimum non-digestible fiber intake occurs at the max milk yield and is usually near…
1.25% of BW per day for cows in mid to late lactation (will be different for early lactation, higher requirements)
how does the NDF intake change with the weeks of lactation?
early on, they need less fiber, but then from weeks 12 to 28 it will be higher and the cow will be eating as much as she can and is limited by physical fill, then later in lactation it decreases again
what is the relationship of milk fat % and mean ruminal pH in lactating dairy cows?
as pH increases, milk fat % also increases
we need which molecule in order to undergo gluconeogenesis to make glucose, which makes lactose, which makes milk
propionate, which comes from starches and grains!
list the following in order of fastest fermentation to slowest fermentation:
- pectin
- cellulose
- soluble carbohydratea
- soluble carbohydrates
- pectin
- cellulose
since dairy cows need fiber, if you decrease the amount of forage in the diet, what do you need to add?
you need to add more NDF from other sources
