ch 3 Flashcards
Aimed at giving information on the capacity of individual feeds to meet the nutritional requirement of the animal. Testing feed quality for animal consumption.
FEED EVALUATION
CONTRIBUTING FACTORS TO
FEED INGREDIENT QUALITY
- Genetic differences
- Soil characteristics
- Degree and type of processing
- Dehulling process
- Storage systems
SAMPLING FEEDS FOR ANALYSIS
Considerations for sampling process:
- Sampling size and sampling scheme
- Sampling equipment
- Sampling preparation and retention
- Sampling purpose
- Type of material to sample
sampling equipment for samples in big containers
slotted grain probe
sampling equipment for samples obtained in sacks
tapered bag trier or buriki
sampling equipment with heaps of feed ingredients
pelican sampler
sampling equipment for liquid ingredients
bomb sampler
METHODS OF FEED EVALUATION
- PHYSICAL METHODS
- PROXIMATE ANALYSIS
- MINERAL ANALYSIS
- DETERGENT FIBER ANALYSIS
- QUICK TEST KITS
- BIOCHEMICAL TRIALS
- Uses naked eye to physically evaluate feeds.
- Insect pests, molds, stones, and other extraneous substances may be observed for their presence.
- Simple stereo microscope can be used to detect Adulteration in feeds.
- Adulteration - the admixture of a pure substance with some cheaper and low quality substance.
- Adulteration = poor feed quality.
PHYSICAL METHODS
- Also known as Weende method.
- Most common chemical method used to determine the amounts of dry matter, moisture, fat, protein, ash, and fiber.
- Nitrogen-free extract is obtained by difference.
- All values obtained in this method are termed “crude”.
PROXIMATE ANALYSIS
*proximate analysis, for?
A known weight of sample is dried in an oven a 105oC
* Loss in weight in drying corresponds to the amount of water.
For the amount of water
*proximate analysis, for?
May be directly analyzed using toluene distillation method.
* Sample is boiled with toluene in a flask.
For high moisture samples
*proximate analysis, for?
Determined using Kjeldahl apparatus.
For protein content
*proximate analysis, for?
Uses Soxhlet apparatus
* Fats are dissolved with organic solvent (petroleum ether).
* Non very reliable because it also dissolves the nonfat substances, hence crude fat.
For fat or lipid content
*proximate analysis, for?
Analyzed by simulating the digestion process of stomach of monogastric animals
* Weak acid → weak alkali
For fiber content
*proximate analysis, for?
Subjects the sample at 550-600oC.
* Solubilizes organic substances then leaving only the ash.
For inorganic components (ash)
- Commonly used for analyzing calcium, phosphorus, salt.
- Ash from proximate analysis is used here.
- Calcium is determined by precipitating ash as calcium oxalate.
- Phosphorus is determined by converting the phosphorus into phosphoric acid.
- Salt is determined by using Volhard method.
MINERAL ANALYSIS
- Active ingredients are detergent compounds.
- Two solutions: neutral detergent solution and acid-detergent solution
DETERGENT FIBER ANALYSIS
✓ Dissolves starches and other soluble fractions of sample, hence leaving only the insoluble fractions (neutral detergent fiber or NDF).
✓ NDFs are cellulose, hemicellulose, lignin and ash.
Neutral detergent solution
✓ Dissolves the hemicellulose from the NDF.
✓ Thus, leaving an insoluble fraction known as the ligno-cellulose plus ash.
Acid-detergent solution
- Give fast and reliable results as compared to laboratory analysis which may take at least a day or two to get results.
QUICK TEST KITS
*Common test kits:
determine the degree at which soybean and soybean meal have been to heat during processing.
Urease test kit
*Common test kits:
for detecting adulteration of rice bran hulls.
Rice bran test kit
*Common test kits:
indicate the amount of aflatoxin and other mycotoxins.
Mycotoxin test kit
*Common test kits:
instantly measure moisture content.
Electronic moisture testers
- Also known as metabolism trial.
- Used to determine the amount of nutrient digested, absorbed, and utilized.
- Uses proximate analysis and live animal.
- Three stages:
o Adjustment
o Preliminary
o Collection
BIOCHEMICAL TRIALS
*stage of biochemical trial
Feed is gradually presented to the animal, until feed intake stabilizes.
ADJUSTMENT
*stage of biochemical trial
Feed intake should already be stable.
* Level of feeding is determined.
* Give allowances in feeding.
PRELIMINARY
*stage of biochemical trial
Feed sample, refusal, feces, and urine are collected regularly.
* Total collection method.
COLLECTION
In vivo means
inside/within the animal
In vitro means
laboratory set up
In vitro methods are more rapid and convenient. Also, more samples can be tested at a given time.
* In vitro methods:
o Gas production method – tests the rate of gas (C02 and CH4) production during fermentation process.
o Tilley and Terry two-stage method – rumen fermentation followed by enzymatic digestion.
o Nylon bag technique – also called as sacco fermentation trial. Sample in nylon or Dacron bag is placed inside rumen.
Different values of feed nutrients:
➢“Fresh basis”
➢“Dry basis”
➢“As fed basis”
➢“Air-dry basis”
