Upload
layne-basting
View
258
Download
1
Tags:
Embed Size (px)
Citation preview
In Vitro, in sacco, in vivo studies of
feeds
Department of Animal Science, Faculty of Agriculture
Khon Kaen University
Prof. Dr. Metha Wanapat
Dr. Anusorn Cherdthong
130740 Tropical Feed Resources and Feeding Technology
The First Step
Know the nutrient composition of your feed ingredients! Discuss the way we determine nutrient concentration in feedstuffs
Key to Nutrient Analysis
The analysis is only as good as the sample you take !!!
1 quart sample has to represent several tons of feed/feedstuff “representative sample”
Sampling Feedstuffs
ID = label containers with your name, address, date, and feed type, etc.
Sampling: Grain or mixed feeds
Sacks: 2 handfuls from 5-7 bags Bulk: 12-15 samples from different areas
Random samples placed in bucket & mixed
Obtain uniform sub-sample
Sampling Feedstuffs
Hay Use a hay probe & take 12-15 samples
from all locations/depths Cut samples into 1-2” lengths & mix in
clean bucket Haylage or Silage
Collect samples during the entire loading process for new
For old, take series of samples (not spoiled)
Sampling Feedstuffs
Grain: send in at least 1 pt Hay: send in at least ½ lb Silage (Wet Feedstuffs): 2 qts in
an airtight container, preferably freeze or refrigerate, or deliver immediately
Samples must arrive at lab in same condition they left your farm!
Why analyze rations or feedstuffs??
Nutrient Analysis
Book values are averages over many locations Your region may differ in the nutrient
density of the feedstuffs it produces Example: Book value for SBM = 48%
CPYour SBM from SD =
46.5% CP Overfeeding/underfeeding nutrients
Contaminants in feedstuffs Toxins, chemical residues, or other
harmful compounds
Nutrient Analysis How often should you analyze your
feedstuffs/rations? Every time you change batches/loads
of feedstuffs When you change feedstuffs in your
rations Every time you mix a new batch of feed
Monthly samples of forages/silages In a perfect world Generally, take sample after harvest
Analysis Systems
Analysis Methods1. Chemical
e.g. titration, chromatography (chemistry) No estimate of utilization, lab errors
2. Biological Animals; Expensive & tedious Difficult to obtain individual nutrient
effects
3. Microbiological Microorganisms; estimations Accurate quantification difficult
Proximate Analysis
Traditional standard of the industry Developed in Germany more than a
century ago Most generally used chemical
scheme for describing feedstuffs Limitations for today’s diet
formulation systems Information is of uncertain nutritional
significance May result in misleading results
Proximate Analysis Fraction Nutrient
Dry Matter (DM) Water
Crude Protein (CP) Protein
Crude Fiber (CF) CHO—Fiber
Nitrogen Free Extract (NFE)
CHO—easily digested
Ether Extract (EE) Lipids
Ash Minerals
Missing? Vitamins
Dry Matter Weigh a sample Heat to 100 – 105 C Re-weigh the sample Difference in 2 weights is
water loss % DM = 100% - % water loss
Ash Weigh a sample Burn for 2 hrs at 600 °C
(1112 °F) Weight remaining is ash Individual minerals not
determined Use atomic absorption,
spectrophotometry to get individual minerals
Ashing Oven
Crude Protein
Kjehdahl Method: Digest a dry sample in concentrated
sulfuric acid Converts N to ammonium
During distillation ammonium is converted to ammonia
mL of acid used to bring ammonia solution to neutral pH = amount of N in sample
Total N x 6.25 = % CP
Digestion Process
Distillation Process
Kjehdahl Method
Important Point: Analysis does not distinguish
between N sources Protein Synthetic amino acids Non-protein N (urea, NH4,
biuret)
Crude Protein Combustion Method (LECO)
N is released at high temperature in presence of pure O2
N determined by thermal conductivity within the instrument
EXPENSIVE equipment!
LECO analyzer
Ether Extract
Fat determination
Boil sample in ether alcohol to extract lipid fraction of sample
Crude Fiber Industry method for fiber
determination BUT--80% of hemicelluloses, 60%
of lignin, and as much as 50% of celluloses can be lost CF value lower than actual amount
of fiber in feedstuff Lignin can attach to N
Overestimated [lignin]
Van Soest Method of Forage Determination
Replaces CF Analysis
Van Soest Fiber Determination
Used to determine the insoluble cell wall matrix & the major subcomponents:
1. Hemicellulose2. Cellulose3. Lignin
Able to determine heat-damaged protein Maillard Products N content of ADF fraction
(ADIN=indigestible N) Tells you the amount of N in a sample
that is actually AVAILABLE to the animal for use
Detergent System
Ground forage sample
ND insoluble fiber (NDF)(cell wall components)
ND solubles(cell contents)
AD insoluble fiber (ADF)(cellulose, lignin)
AD solubles(hemicellulose, cell wall N)
Acid insoluble lignin Solubles (cellulose)
Lignin by loss of ignition
Digest with neutral detergent (ND)
Digest in acid detergent (AD)
Digest with 72% H2SO4
Detergent Digestion System
Summary
NDF = hemicellulose + cellulose + lignin
ADF = cellulose + lignin
ADL = lignin
Others Vitamins
Individual assays for each vitamin Chemical/biological assays using
chromatography
Minerals Assays to obtain concentration of
individual minerals Using Atomic Absorption
Spectrophotometry
Energy Determination
Total digestible nutrients (TDN) vs. Bomb Calorimetry Explained in “Energy Systems”
How to do research experiment ?
Feedstuff Evaluation
Remember—Chemical analysis is the starting point for determining the nutritive value of feeds
The actual value of ingested feedstuffs is dependant upon the ability of the body to make use of the nutrients in the feedstuff
Feedstuff Evaluation
Two general classifications of methods In vitro methodology: Simulate
digestion in a test tube to estimate nutrient digestibility
In vivo methodology: Feed animal and measure response criteria
Growth Retention/Excretion Digestibility
A. In vitro methodology
Method to estimate digestibility of feedstuffs Uses enzymes and (or) microorganisms in
a test tube to simulate GIT environment
Method is cheap, with results in about 24 - 48 hours
Rough estimate of digestibility
In vitro methodology
Use enzymes to simulate digestion in upper GIT Mouth Stomach Small Intestine
Use fecal inoculant to simulate fermentation in lower GIT Large Intestine
In vitro methodology
In Vitro Gas TechniqueMenke and Steingass, 1988)
Sample preparation :
• All substrate should be milled using a 1 mm screen
• Weigh 200 mg substrate into each syringe
• Blank (RF + artificial saliva)
• Sample should be done in duplicate or triplicate
Artificial Saliva preparation :
• add distilled water, buffer solution, macro- and micro-
mineral solution, resazurin solution into round flat-
bottomed flask.
• warm to 39 oC then add reducing solution
• place water bath set at 39 oC on magnetic stirrer
• put magnet into flask and gentle bubble CO2 into
solution until blue color turns to pink then clear-
• provide a stream of CO2 and an O2 free atmosphere,
buffer should be pH 7.0-7.3
• collect RF from animal, strain RF through three layers
of gauze, final ratio of artificial saliva:RF (2:1).
• pour the SRF into the artificial saliva, make sure the
magnet is stirring properly during the whole process of
dispensing the RF/artificial saliva into the syringe.
• add 30 ml of solution to each syringe using a dispenser.
• fill the syringe, then open the clip and gentle push the
syringe’s plunger so that all the air is removed.
• record the volume and place in water bath.
Rumen fluid preparation :
Reading taken :• Forage 3, 6, 12, 24, 48, 72 and 96 hr.
• Concentrate it may be necessary to take more reading
in the first24 hrs.
• It is advisable to gentle mix each syringe 2-3 times
during the first day as well as each time a reading is
taken.
Macromineral solution Micromineral solution
Na2HPO4 5.7g CaCl22.H2O 13.2g
KH2PO4 6.2g MnCl24.H2O 10.0g
MgSO4 0.6g CoCl26.H2O 1.0g
make up to 1 L with distilled water FeCl26.H2O 0.8g
make up to 1 L with distilled water
Artificial saliva : Resazurin aqueous
NaHCO3 35g (100mg/100ml)
(NH4)HCO3 4g
make up to 1 L with distilled water
Preparation of artificial saliva :volume (ml)
Artificial saliva-final volume 500 1000 1500 2000
Distilled water 237.5475.0712.5950.0Macromineral solution 120.0240.0360.0480.0Buffer solution 120.0240.0360.0480.0Micromineral solution 0.06 0.12 0.18 0.24Resazurin 0.61 1.22 1.83 2.44
Reducing SolutionDistilled water 23.8 47.5 71.3 95.01M NaOH 1.0 2.0 3.0 4.0Na2S9H2O (mg) 168 36 504 672
B. In vivo methodology
I. Feeding trials Simply give an indication of:
Palatability of feedstuff in a ration (will the animals eat it?)
Growth response compared to another feedstuff/ration
Tells NOTHING of why different results were obtained
Type of Feeding Experiment
Feeding trials ---> Growth, Production, reproduction
Slaughter experiment --> meat component, market value
Digestion trials --> Intake, digestibility
Balance trials ---> measure nutrients retention
Feeding Trials Compare between > 2 rations Feed intake (input-feed cost) Growth, milk production ,
reproduction, or other function efficiency of feed utilization ADG, weekly gain, final (weight %
initial wt (%) , FCR
Body size: height, length, circumference etc.
Milk production: yield ( average, lactation) persistency, peak, composition & yield
Egg : hen day, hen house etc. Draft animal : Speed, Area , time
ets Experimental designs: Factorial, LS
etc.
Feeding Trials with Laboratory Animals
Small animals e.g. Rat Growth, reproduction, lactation cheap (feed, labor, short life cycle) Useful for fundamental principle of
Nutrition
The purified-diet Feeding Trials Methods
Diets contain of purified source of nutrients
E.g. Casein as protein, urea, starch as CHO
Specific nutrient interested more completely diet --> less
satisfactory on Animal
Feeding Management in the Trials Group Feeding vs Individual
Feeding group - simplest equipment need cheap labor cost complicate in the interpretation of
results some animal many consume less feed
Individual correlation of individual performance
with food intake statistics analysis advantage
Controlled vs ad libitum feeding Ad libitum is the most common in farm
practice Gives unbiased results of direct practical Measure : feed required per kg gain
total increase in body weight n Does one animal grow because it eats more
or the other fail because it eats less ?”
Slaughter Experiments
Killing of the animal when require specific information
Analysis of certain specific tissues or whole body
e.g. Protein source - protein tissue & concentration
(Initial - Final) composition of body chemical Time & labor cost
Slaughter Experiments
Measures of market value: carcass, dressing percentages carcass quality, quality of product, selling price
Meat quality, color, vitamin), fat thickness
Balance trials Provide more information than digestion trial
Measure: nutrient retention (Positive or negative)
Needed to accurate & Precisely measurement method
Use Metabolism cages-intensive care Example: N-retention study
(N-Intake)- (Nexcretion )= N balance Short period but, useful information
Feeding Trials
In vivo methodology
II. Metabolism Trial Determines nutrient
retention/excretion Complete analysis on ration Feed known amount to animals Collect urine/feces Compete analysis on urine/feces
Metabolism Trial
In vivo methodology
Metabolism Trial Calculation: [(In – Out)/In] * 100
Nutrient retention = Nutrient intake –Nutrient excretion (Urine + Feces) x 100Nutrient intake
In vivo methodology
III. Digestibility studies
Use of cannulated animals
Can determine small intestinal digestibility (hydrolytic digestion) as well as total tract digestibility (hydrolytic + fermentative digestion) of nutrients
Cannulated Animals
Cannulated Animals
Cannulated Animals
In vivo methodology
Digestibility studies
Effluent from small intestine or rumen or feces is collected and analyzed for nutrient(s) being studied
In vivo methodology
Digestibility studies
Collection at terminal SI is referred to as ileal digestibility
Collection of feces determines total tract digestibility
In vivo methodology How is TRUE digestibility
determined? Usually only in monogastrics Usually only concerned with true
AA digestibility Chicken—cectomized animals
Surgically remove ceca from birds and measure digestibility
Pigs—feed diet containing no protein
In vivo methodology Determination of endogenous
losses Endogenous losses
Sloughed intestinal cells Sloughed microbial cells Enzymes Mucin
Measure AA output from protein-free diet = endogenous losses
Corrects for AA present but not of feed origin
In vivo methodologyIV. In-Situ digestibility
Digestibility within a localized area or position
rumen, abomasum, small intestine
Use cannulated animals Mesh bag to contain the feedstuff and allow
microbial action to take place
Determine Rate/extent of digestibility
The use of indigestible marker in nutrition
studies
Disadvantage of conventional trials Time consuming expensive animal condition e.g. grazing & stall
grazing : select feeding
Employed of indigestible marker or reference substances
Extensively used in grazing research
Determination propose digestibility and intake rate of passage of nutrients in GI
tract site and extent of digestion microbial protein synthesis (e.g.
in ruminant)
The ideal marker Inert, no toxic on animal & micro
flora not be absorbed or metabolized in
GI mixed well/ associated with feed should not influence GI secretion
digestion absorption or motility precise - quantitative analysis /
not interfere with other analysis
Two type of marker use in nutrition studies
Internal marker component of
feedstuffs e.g. lignin,
AIA, indigestible ADF, NDF
External marker
indigestible substances added to a feedstuff
e.g. Cr2O3 (chromium sesquioxide)
Cerium Dysprosium ytterbium ruthenium
phenanthroline complex
binding marker with a specific feed. E.g. Yb labeled feed
Other typed of marker
Measure microbial protein synthesis maker to determine amount
of microbial protein synthesis
Total protein passing to the lower tract in ruminant
determine portion of total protein : microbial origin
Marker specific to bacteria Diaminopimelic acid (DAPA)
found only in bacteria Determine DAP content in digesta and
DAP:N ratio in bacteria therefore, estimate portion of nitrogen
in digesta from microbial origin Ribonucleic acid (RNA)
assumed that feed RNA 100% digest in rumen
thus, only bacterial RNA passes to lower tract
determine RNA: N ratio in bacteria and % digesta RNA, then --> microbial protein synthesis calculated.
Purine (Adenine, Guanine) and purine derivatives (urine,plasma)?
Use of marker to estimate digestibility
Total tract vs. specific site digestibility Total tract = (intake - fecal) x100 / intake (Marker) Nutrient digestibility, %
= 100 - 100 x % marker in feed x nutrient in feces
% marker in feces % nutrient in feed
Digestibility in specific sites of digestive tract
“Slight modification of total tract digestion”
e.g..
Nutrient digestibility in rumen, %
= 100 - 100 x % marker in feed x % nutrient in duodenum
% marker in duodenum % nutrient in feed
Use of marker to measure feed Intake
Feed intake effect on economy & livestock production
Difficult to measure in take in grazing ruminant
Indicator methods to estimate intake Information: fecal excretion and
digestibility
How to estimate digestibility?
Use of marker techniques
Conventional digestion trial
In vitro DM digestibility
How to estimate fecal output?
Fecal collection bags Total collection of feces Indigestible marker e.g. chromic
oxide Fecal output,g = indicator consumed
(g/day)/Indicator concentration in feces(g/g DM)
Use of marker to measure rate of
passage Particulate & fluid materials Fluid flow rate or fluid dilution
rate(% of fluid volume leaving the rumen per hour)
Faster dilution rate ==> more efficient microbial growth
Increase rate of passage ==> increased voluntary feed intake
Use of marker to measure rate of passage(cont....)
Marker for measure rate of fluid passage from the rumen Chromium EDTA (Cr-EDTA) Cobalt EDTA (Co-EDTA) Polyethylene glycol (PEG)
Measurement the rate of fluid passage
Flow rate at a sampling site = infusion rate(g/d)/marker
concentration at sampling point(g/ml)
Measurement of particulate passage
rate Single dose vs.. continuous dose Calculate flow rate or volume of
particulate phase Common particulate phase marker for
estimate turnover rate Chromic oxide Ytterbium Dysprosium Cerium Ruthenium phenanthroline complex Internal marker e.g. indigestible ADF,NDF
and AIA
Measurement of particulate passage
rate(cont..)
Bind the marker with feedstuffs (soak, with rare earth) then fed or dosed for estimation of passage rate
Marker for the measurement of
microbial protein synthesis
Marker Diaminopimelic acid RNA Purines
Good Luck!!