ANSC 221 Final Exam 2 Feeds, Energy
Calculations, Grains, and By-products
Questions Well Answered 2026-2027
Updated.
Gross Energy - Answer amount of energy that can be derived from feed by combustion; all the
energy in the feed (not all is available to animals)
Digestible energy - Answer GE - Feces; energy not released in feces therefore it was absorbed,
still not all used by animal
Metabolizable energy - Answer GE-Feces-Urine and gas; left after accounting for all three
excretions; still not all available to animal
Net energy - Answer ME - Heat increment; heat of digestion; energy that the animal can use
for productive purposes (maintenance, gain, reproduction, milk production)
Caloric energy - Answer determined using bomb calorimetry; one calorie = energy to raise 1g
H2O 1 C; 1000 calories = 1 Kcal;
calculations of bomb calorimetry - Answer temp rise x g H2O = calories in sample, multiple by
amount of feed given to get calories in feed and feces;
TDN - Answer total digestible nutrients; really means an energy index calculated from proximal
analysis; highest TDN value would be 225 if the sample were all fat (x2.25) lowest is 0; works
well for ruminants
two aspects of measuring protein value - Answer digestibility and biological value
Biological value - Answer retention of the digestible part of the protein which serves as an
index of protein quality; proportion of digested protein N that is retained; depends on AA
% apparent nitrogen digestibility - Answer N in feed-N in feces /N in feed x 100
Nitrogen balance - Answer N in feed - N in feces - N in urine; can be + or -
% nitrogen retention - Answer N in feed - N in feces - N in urine / N in feed x 100
,True N digestibility - Answer N in feed - (N in feces - metabolic fecal nitrogen) / N in feed x 100
apparent biological value - Answer N in feed - N in feces - N in urine / N in feed - N in feces x
100
True biological value - Answer (Nfeed - (Nfeces - MFN) - (Nurine - EUN)) / (Nfeed - (Nfeces -
MFN))
EUN = endogenous urinary N
Protein in rumen - Answer bacteria used to digest CHO to VFA, remodel proteins to essential
AA and utilize NPN, Manufacture B vitamins
Degradable intake protein - Answer protein that is soluble and available to microbes to build
bacterial crude proteins; construct new AA; broken down into keto acids and ammonia
metabolic protein - Answer protein enters SI and comes from feed N and bacterial N; UIP is
the feed N that makes it to the SI unaltered; BP or BCP is the protein produced by the bacteria
in fermentation in the rumen
Grain trade versus animal feeding - Answer GT: test weight, level of foreign materials, color,
fines and broken kernels, moisture; AF: level of energy, level of protein, lysine (nonruminatns),
availability of nutrients
Foreign material - Answer depends on the material, some are way worse than others;
test weight - Answer measure of density; almost no effect if they can eat enough feed to meet
energy needs
broken kernels - Answer for livestock, we grind it anyways; but broken kernels are more
susceptible to damage and mold
High moisture corn - Answer higher digestibility of fats; spoils more readily; biggest plus is
from limiting feed wastage; can be equal to dry corn; not better for swine therefore it usually
depends on different factors: availability of fuel for drying corn, equipment to keep it wet,
harvest time, equipment or labor to feed it everyday, etc.
palatability - Answer pigs will display preference if given choice
, feeds most susceptible to mycotoxins - Answer corn, wheat, oats, barley, sorghum,
cottonseed, peanut meal, rye
other common molds - Answer penicillium - common blue mold capable of producing
mycotoxin, usually does not
diplodia - affected cattle and sheep in africa
prevent mycotoxins - Answer inhibit mold growth with drying, refrigeration, or mold
inhibitors; prevent contamination; use clean procedures
Proximate analysis - Answer used to analyze feeds; water, CP, CF, EE, Ash, and NFE
water - Answer · Weigh an original sample of feed
· Place in over at 90-95 C to remove water
· Remove it, cool it, weigh it
· Follow procedure manual or repeat until you get constant weight and temp
· Calculate the water lost by differences of weight
· Divide by original sample weight / 100
CP - Answer · Kjeldahl method
· Weigh OG sample
· Plae in Kjeldhal flask and boil with sulfuric acid converting N
· Cool, dilute, neutralize
· Multiply the amount of nitrogen by 6.25
· % by dividing the CP by OG sample weight x 100
EE - Answer · Direct and indirect (more common) way to do this
· Weigh OG sample
· Dry and weigh again
· Reflux sample with ether to remove fat
· Dry and weigh sample giving moisture free, fat free sample
· Subtract last weight from weight after water removal
· Divide by OG sample weight x 100
CF - Answer · Weigh OG sample
Calculations, Grains, and By-products
Questions Well Answered 2026-2027
Updated.
Gross Energy - Answer amount of energy that can be derived from feed by combustion; all the
energy in the feed (not all is available to animals)
Digestible energy - Answer GE - Feces; energy not released in feces therefore it was absorbed,
still not all used by animal
Metabolizable energy - Answer GE-Feces-Urine and gas; left after accounting for all three
excretions; still not all available to animal
Net energy - Answer ME - Heat increment; heat of digestion; energy that the animal can use
for productive purposes (maintenance, gain, reproduction, milk production)
Caloric energy - Answer determined using bomb calorimetry; one calorie = energy to raise 1g
H2O 1 C; 1000 calories = 1 Kcal;
calculations of bomb calorimetry - Answer temp rise x g H2O = calories in sample, multiple by
amount of feed given to get calories in feed and feces;
TDN - Answer total digestible nutrients; really means an energy index calculated from proximal
analysis; highest TDN value would be 225 if the sample were all fat (x2.25) lowest is 0; works
well for ruminants
two aspects of measuring protein value - Answer digestibility and biological value
Biological value - Answer retention of the digestible part of the protein which serves as an
index of protein quality; proportion of digested protein N that is retained; depends on AA
% apparent nitrogen digestibility - Answer N in feed-N in feces /N in feed x 100
Nitrogen balance - Answer N in feed - N in feces - N in urine; can be + or -
% nitrogen retention - Answer N in feed - N in feces - N in urine / N in feed x 100
,True N digestibility - Answer N in feed - (N in feces - metabolic fecal nitrogen) / N in feed x 100
apparent biological value - Answer N in feed - N in feces - N in urine / N in feed - N in feces x
100
True biological value - Answer (Nfeed - (Nfeces - MFN) - (Nurine - EUN)) / (Nfeed - (Nfeces -
MFN))
EUN = endogenous urinary N
Protein in rumen - Answer bacteria used to digest CHO to VFA, remodel proteins to essential
AA and utilize NPN, Manufacture B vitamins
Degradable intake protein - Answer protein that is soluble and available to microbes to build
bacterial crude proteins; construct new AA; broken down into keto acids and ammonia
metabolic protein - Answer protein enters SI and comes from feed N and bacterial N; UIP is
the feed N that makes it to the SI unaltered; BP or BCP is the protein produced by the bacteria
in fermentation in the rumen
Grain trade versus animal feeding - Answer GT: test weight, level of foreign materials, color,
fines and broken kernels, moisture; AF: level of energy, level of protein, lysine (nonruminatns),
availability of nutrients
Foreign material - Answer depends on the material, some are way worse than others;
test weight - Answer measure of density; almost no effect if they can eat enough feed to meet
energy needs
broken kernels - Answer for livestock, we grind it anyways; but broken kernels are more
susceptible to damage and mold
High moisture corn - Answer higher digestibility of fats; spoils more readily; biggest plus is
from limiting feed wastage; can be equal to dry corn; not better for swine therefore it usually
depends on different factors: availability of fuel for drying corn, equipment to keep it wet,
harvest time, equipment or labor to feed it everyday, etc.
palatability - Answer pigs will display preference if given choice
, feeds most susceptible to mycotoxins - Answer corn, wheat, oats, barley, sorghum,
cottonseed, peanut meal, rye
other common molds - Answer penicillium - common blue mold capable of producing
mycotoxin, usually does not
diplodia - affected cattle and sheep in africa
prevent mycotoxins - Answer inhibit mold growth with drying, refrigeration, or mold
inhibitors; prevent contamination; use clean procedures
Proximate analysis - Answer used to analyze feeds; water, CP, CF, EE, Ash, and NFE
water - Answer · Weigh an original sample of feed
· Place in over at 90-95 C to remove water
· Remove it, cool it, weigh it
· Follow procedure manual or repeat until you get constant weight and temp
· Calculate the water lost by differences of weight
· Divide by original sample weight / 100
CP - Answer · Kjeldahl method
· Weigh OG sample
· Plae in Kjeldhal flask and boil with sulfuric acid converting N
· Cool, dilute, neutralize
· Multiply the amount of nitrogen by 6.25
· % by dividing the CP by OG sample weight x 100
EE - Answer · Direct and indirect (more common) way to do this
· Weigh OG sample
· Dry and weigh again
· Reflux sample with ether to remove fat
· Dry and weigh sample giving moisture free, fat free sample
· Subtract last weight from weight after water removal
· Divide by OG sample weight x 100
CF - Answer · Weigh OG sample
