Feed Energy Flashcards
what is feed energy
property of nutrients (nutrient adjacent)
what nutrients supply energy
carbohydrates
lipids
proteins
gross energy
potential energy of a feed
provides limited information on actual energy
why is gross energy not a good measure of true energy
doesn’t account for losses or digestibility
EX. corn and hay have similar gross energy
how do you measure gross energy
bomb calorimeter(heat of combustion)
equation for digestible energy(DE)
gross energy - fecal loss
why are DE and TDN similar in accuracy
they don’t account for losses from methane, urine, and heat increment
average fecal energy loss in pigs
3-10%
average fecal energy loss in horses
10-40%
average fecal energy loss in high grain fed ruminants
10-30%
average fecal energy loss in high roughage fed ruminants
40-60%
how are DE and TDN different
DE uses bomb colorimeter
TDN uses proximate analysis
equation for metabolizable energy
DE - Urine energy - methane
equation for net energy
ME - heat increment
what is the most accurate estimate of feeds energy value
net energy
what is heat increment
heat of digestion/eating/metabolization
when is the only time heat increment is useful
during cold stress
which has a higher heat increment: roughage or grains?
roughage
what can you feed to lower stress/heat increment
fat
NEm
net energy used for maintenance
NEg
net energy used for growth
NEI
net energy used for milk production
NEp
net energy used for fetal development
why do cows have lower heat increment than horses
enzymatic cost of ruminating is less than eating
how is heat production measured
indirect-respiratory calorimeter
measure CO2 that goes in vs. CO2 that comes out
how is the heat intake caused by different feedstuff measured
feed is fed at one amount and heat produced is measured
feed is then fed a t a higher amount and heat produced is measured again
the steeper the line produced the higher the heat increment
why will feeds high in fiber CHO have lower NE values that feeds high in starch CHO
bc fiber causes higher fecal, methane and heat increment losses
