Ch. 3: Methods of Analysis for Nutrients and Feedstuff

Why do we analyze nutrients and feedstuffs

to measure and compare the chemical and nutrient composition of feedstuffs for animal feeding

what does the analysis for nutrients and feedstuffs help with

selection of feedstuffs and guide in feed formulation

samples for analysis must be …

representative of the pool from which they came

isolating or identifying certain compounds in the feed

qualitative analytical chemical procedure method

gravimetric(dealing with weight) procedure or other methods involving use of acid or base in titration to quantify nutrients in the feed

quantitative analytical chemical procedure method

using animals- feed the feed to animals and measure growth or other products from the animal

biological analytical method (gives more accurate estimate of animal utilization and more expensive)

involves the use of microorganisms

Microbiological analytical method

most common procedure in animal nutrition

dry matter determination

weight of feed minus the moisture

dry matter

all the nutrients in feed are found in …

dry matter

dry matter determination methods

oven drying(simplest)

vacuum drying(materials that could be damaged by high temp)

freeze drying(dehydration)

distillation with toluene(materials containing volatile substances)

laboratory/analytical procedures that determine the various nutritional fractions of feedstuff

proximate analysis

proximate analysis divides feed into what 6 fractions

water, crude protein, ether extracts, ash, crude fiber, and nitrogen free extracts

why is the protein determined called crude protein

feeds contain compounds that are not true protein source, it contains true and non true proteins

nitrogen determined is multiplied by … to obtain % crude protein in the feed

6.25

ground sample extracted with either(organic solvent) for 4 hours

ether extract

ether will extract what ether soluble organic compounds

true fats and fatty acid ester, compound lipids, and fat-soluble vitamins

residue remaining after all combustible material (minerals)has been burned off

ash

detergent extraction methods

neutral detergent fiber and acid detergent fiber

insoluble residue includes acid detergent fiber

cellulose, lignin, and lignified N

insoluble materials

neutral detergent fibers

used to analyze for several minerals

atomic absorption spectrophometry