Module 1- overview of animal nutrition Flashcards
what are the 2 broad categories of animal nutrition?
1) maintenance functions- nutrients to keep animal alive
2) productive functions
- production of food for human consumption
6 major reasons why animal nutrition is important
1) efficiency
2) disease susceptibility & recovery
3) quality of product
4) reproductive success
5) economics -> feed efficiency
6) environment - GHG emissions, N/P excretion
what is a nutrient
chemical element or compound that is required for normal body functions
6 major classes of nutrients
1) carbs
2) lipids
3) protein
4) minerals
5) water
6) vitamins
most important nutrient
water
essential vs non-essential nutrients
essential: must be provided in the diet bc the body cannot make sufficient quantities
non-essential: body can make in sufficient quantities
- building blocks must be available though
ration definition
specific daily allocation that an animal needs to eat
diet definition
mixture of foodstuff or feedstuff that is going to provide required nutrients
how do plants synthesize proteins?
use nitrogen to make AA
what does the metabolism of carbs & fat provide to the animal
energy
what type of feeds contain high protein? why?
- animal based feeds & plant by-products
- when oil is removed=protein becomes concentrated
composition of the animal body (water, protein, fat, minerals, carbs %)
60% water
16% protein
20% fat
4% minerals
<1% carbs
protein : fat ratio will ( ) as animals get older
decrease
what increases with age?
fat
digestion
break down feed into smaller molecules for absorption
when does digestion, absorption & metabolism occur?
digestive tract- digestion & absorption
post-absorptive- metabolism
chemical breakdown of feed
HCI & gastric secretions
digestion is composed of what 2 types of feed breakdown
physical & chemical
gastric digestion
facilitated by enzymes secreted by the animal
primary form of digestion for monogastrics
gastric digestion
fermentative digestion
digestion that takes place in specialized compartments that are located before the stomach & small intestine, or after the small intestine
animals who digest before stomach & small intestine vs after
before- ruminants
after- horses
T or F: pigs primarily use gastric digestion, but still have hund gut fermentation
T
flow of monogastric digestion
1) mouth
2) esophagus
3) stomach
4) small intestine
5) cecum + colon (large intestine)
salivary amylase function
digest starches in mouth
3 accessory digestive organs of monogastric
1) teeth
2) salivary glands
3) liver
stomach functions (4)
1) muscular contractions
2) HCI secretion
3) pepsinogen secretion
4) chyme formation
chyme
partially digested feed + water + HCI + enzymes
pH of chyme
2-3
where does most of the absorption take place in monogastrics?
1st 2 compartments -> duodenum + jejunum
duodenum function
secretion of pancreatic juices that contain bicarb will buffer chyme so enzymes can function
liver function (2)
1) produce bile
2) lipid digestion with bile salts
gallbladder function
stores bile
what are brush border enzymes produced by
villi & microvilli
list 4 differences between chicken and pig digestion?
1) no teeth -> use beak
2) crop-> feed storage
3) proventriculus-> secrete HCI & enzymes
4) gizzard- mechanical digestion of feed
how does mastication help digestion
smaller particles increase surface area for enzymes to act on
reticulum vs omasum structure
reticulum- honeycomb
omasum- leaves of tissue that squeeze water out of feed
where is gastric digestion initiated in ruminants
abomasum
T or F: small intestine secretions in ruminants are very similar to pigs
T
the rumen is an ( ) environment. why?
anaerobic
- supports growth of microorganisms
what are the 2 most important microorganism groups in the rumen
bacteria & protozoa
what GHG do archaea produce
methane
why is it necessary bacteria in the rumen are attached to feed particles?
enzymes are on outside wall of microorganism so they must come into contact with feed in order for fermentative digestion to take place
what does microbial fermentation of starch, cellulose & hemicellulose produce?
VFAs
where are VFAs primarily produced & absorbed
rumen
what are the 3 VFAs
1) acetate
2) propionate
3) butyrate
what is the major source of energy for ruminants?
VFAs, then microbial protein
microbial protein
major source of protein formed by amino acids for the animal
major site of absorption for monogastrics
small intestine
end product of protein digestion
amino acids
end product of starch digestion
glucose
end product of lipid digestion
fatty acids -> go to lymphatic system
what facilitates absorption
villi
villi
tiny projections into the lumen of the small intestine
microvilli
tiny hair-like projections that line the villi
how os O2 supplied to small intestine?
there is a rich blood supply to villi & microvilli
venous drainage
takes away nutrients that have been absorbed
lacteal function
takes away end products of lipids by absorbing & draining into lymphatic system
major functions of microvilli (2)
1) increase surface area for absorption
2) produce brush border enzymes
brush border enzymes are important for what digestion of what 2 nutrients?
carb & protein
density of papillae in the rumen depends on what?
type of diet
what type of diet produces lots of VFAs?
high grain
T or F: rumen papillae do not secrete enzymes
T
rumen papillae function
increase surface area
major site of absorption in ruminants
rumen & small intestine
major site of absorption in monogastrics
small intestine
3 mechanisms of absorption
1) diffusion
2) facilitated diffusion
3) active transport
diffusion & example
moving down from high to low concentration
- glucose in lumen -> bloodstream
facilitated diffusion
uses transporter to facilitate movement of substrates from high to low concentration
active transport
requires ATP, goes against concentration gradient (low to high concentration)
retention time
amount of time the feed spends in the GI tract
retention time is longer in what kind of animals
large animals that depend on fermentative digestion
what does retention time depend on?
body size
animals who use fermentative digestion are more dependant on a higher contribution of energy from?
VFA
anabolism
building of complex compounds from small molecules
- uses energy
catabolism
breakdown of molecules into smaller energy
- releases energy
example of catabolism
generation of ATP
- glucose oxidation to produce ATP
3 factors that may change optimal range of nutrients
1) type of animal
2) physiological state
3) environmental conditions
what type of defect is when we see a decrease in production
functional defect
5 characteristics that make a good diet
1) contain essential nutrients in correct amounts
2) palatable
3) digestible
4) economical
4) non-toxic
feed costs account for ()% of production costs
50
example of nutrient inhibitor
trypsin in soybean
what is the central metabolic junction
glucose
T or F: energy is a nutrient
F
2 major energy substrates
carbs & fats
when would proteins be used for energy?
if diet is deficient in carbs/fats
what is the primary form of nitrogen secretion
urea
T or F: vitamins & energy supply energy
F
2 examples of feeds put into a diet to provide energy?
1) cereal grains - barley, wheat, corn, oats
2) lipids: canola seed, flax, soybean
T or F: canola meal is a sufficient source of energy in the diet
F -> only contains 2% fat
what is the fuel of metabolism
energy
energy =
the potential to do work
bomb calorimetry
measures the gross energy of feed
gross energy
heat released when feed is completely oxidized to CO2 & H2O
heat of combustion of feed =
gross energy of feed
what will be produced feed is when oxidized in a cell, not bomb calorimeter
energy in form of ATP
what does the water in bomb calorimetry represent
amount of heat produced
- can measure this by measuring temp of water before & after
how much O2 is added to bomb calorimetry
25-30 atmospheres
energy equivalent of bomb calorimerty
correction factor to account for heat capacity of calorimeter & environment
what is often used as an energy equivalent
benzoic acid
hydrothermal equivalent (HE)=
weight of sample x gross energy / temp 2 - temp 1
GE=
HE x diff in temp / sample weight
kcal vs mcal
kcal- 1000 calories
mcal- 1000 kcal
why are fats more energy dense?
contain more carbon & hydrogens compared to proteins & carbs
lipids has ( )x more energy than carbs & protein
2.25
limitation of gross energy
does not tell how much of that energy is available to the animal
T or F: GE is not 100% available to the animal
T
why is GE not 100% available to the animal
does not account for energy losses due to digestion & metabolism of the feed
what is the single largest loss of energy that is consumed by the animal
fecal energy
T or F: feed is 100% digestible
F
why is it apparent digestible energy?
bc of sloughed off epithelial cells, microorganisms & enzymes
what happens if you do not account for sloughed off epithelial cells in the feces
overestimate how much energy is lost in the feces
what factor affects gross energy value of the feed
chemical composition
is DE higher in monogastrics or ruminants? why?
monogastrics
- pigs have more digestible feed
metabolizable energy (ME) =
DE - (UE-GEL-GILL)
how is energy content of urine determined
bomb calorimetry
major energy loss in urine in monogastrics vs avian species
monogastrics- urea
avian- uric acic
T or F: fermentative digestion of feed is inefficient
T
UE loss is higher in which animals
ruminants
higher ( ) diets produce more methane
forage
what is used to measure gaseous losses in cattle
uses SF6
net energy
accounts for energy lost as heat during digestion & metabolsim
NE=
ME - heat increment
why would feed intake decrease during summer?
animal is trying to regulate body temp bc heat production increases after a meal
do ruminants or monogastrics have a higher heat increment?
ruminants
increase in diet digestibility = ( ) in heat increment
decrease
do forages or grain digestion produce more heat
forages
animals in a catabolic state have a ( ) heat increment than anabolic state animals
higher
amino acid imbalance causes a ( ) heat increment
higher
more frequent feeding has ( ) heat increment than less frequent feeding
smaller
why does feeding smaller, more frequent meals produce a smaller heat increment compared to feeding larger, less frequent meals?
work of digestion for smaller meals is smaller = less heat produced
direct vs indirect calorimetry examples
direct: heat production
indirect: O2 consumption, carbon & nitrogen balance
direct vs indirect calorimetry
direct: heat production measured directly
indirect: gaseous exchange to estimate heat loss
closed circuit calorimetry
totally enclosed, no air is leaving
- can measure how much CO2 is absorbed
open circuit calorimetry
atmospheric O2 is entering, measure how much CO2 is produced
2 advantages & disadvantages of net energy
advantage:
- accounts for metabolic cost of nutrient metabolim
- can predict performance of animal
disadvantage:
- expensive
- time consuming
what energy is used to formulate pig diets
NE
what energy is used to formulate poultry diets
ME
what energy is used to formulate ruminant diets? why?
NE
- heat increment & gaseous energy losses are large so need to account for these
TDN
total digestible nutrients
- used to express energy content of feed before bomb calorimetry
TDN uses values from
proximate analysis
proximate analysis system
used to measure composition of the feed
T or F: TDN looks at digestible nutrients that are contained in the feedstuffs
F
DE for pigs, ruminants fed concentrate & ruminants fed roughages
pigs: 80%
concentrate: 70%
roughages: 50-60%
