classification of nutrients

6 major nutrients

water, carbohydrates, lipids, protein, minerals, vitamins

water

lubrication, involved in biochemical reactions, blood, & bodily fluids

carbohydrates

energy

protein

structure (muscle & connective tissue), enzymes, hormones

lipids

energy, cellular structure, hormone synthesis

minerals

various functions, acid base balance (electrolytes), structure (bone), electrophysiological functions

vitamins

help to maintain overall health and wellbeing, growth and development, immune functions

in vivo

performed on the animal to observe health

in vitro

lab analysis, studies performed outside of the animal

in situ

meaning in the site, method used to study how feed ingredients are digested, “in its original place”

wet chemistry

nutrient composition is analyzed using analytical chemistry

• advantage: more accurate

• disadvantage: much more labor intensive and expensive 

Near Infrared Reflectance Spectroscopy (NIR)

uses optical sensors to determine reflectance of light off of a sample & generates a spectra. it estimates nutrient values from spectra generated by using a library generated through wet chemistry

• advantage: much faster, cheaper, easier

• disadvantage: less accurate, only as good as the library of samples used, novel sample types cannot be analyzed

which nutrients cannot be measured using NIR (Near Infrared Reflectance Spectroscopy)

minerals

ADIN

acid detergent insoluble nitrogen-includes heat damaged proteins and they are proteins unavailable to the animal for digestion

NDIN

neutral detergent insoluble nitrogen-represents protein that is slowly degraded in the rumen, it is less commonly used than ADIN but still useful

why are ADIN and NDIN measured

in order to allow fiber bound proteins & to determine the availability of protein for livestock and ruminants. it also helps to determine the nutritional value of feed, detect heat damaged protein, and to formulate effective rations

which nutrient is ash a measure of and how is it determined?

• mineral

• determined by burning sample at 500 degrees celsius in a muffle furnace

what is the relationship between ash and organic matter

organic matter is the remaining feed after ash is removed

Why is the detergent fiber system (NDF & ADF) an improvement over the crude fiber as a measure of fiber concentration within feeds

Because its more accurate & predicts voluntary intake

What nutrient is ether extract used to measure

Measures fats and lipids

What are the limitations of ether extract

• waxes and pigments are also soluble in ether & don’t provide any nutritional value to the animal

• % fat vs waxes/pigments varies by feedstuff

What is the superior measure to determine the concentration of the same nutrient ether extract is used to measure

boil the sample in ether which dissolves polar compounds, then filter the liquid solvent and dissolve lipids through filter paper. Lastly, the solvent is evaporated leaving only the lipids behind

5 components of proximate analysis system

Crude protein, ether extract, crude fiber, ash, nitrogen free extract

How is crude protein determined

CP = %N x 6.25

How is ether extract determined

By using diethyl ether as a solvent to dissolve fats and other fat soluble substances from a dried ground sample

How is crude fiber determined

boil fiber in sulfuric acid and then sodium hydroxide

How is ash determined

determined by burning sample at 500-600 degrees celsius in a muffle furnace

How is nitrogen free extract determined

difference between 100% and the sum of percentages of moisture, crude protein, crude fat, crude fiber, & ash in a simple feed

What is the equation used to determine the crude protein of feeds

CP = %N x 6.25

Why do we report feeds and diets on a dry matter basis

To eliminate variability of water content which allows for a fair and accurate comparison of the nutrient concentration and overall nutritional value of different feeds

How is dry matter of feeds determined

determined by adding the percent moisture with the percentage dry matter in order to get to 100%. The ground sample is weighed, dried in over until stable, and weighed again. It is then dried in an oven for a set time and temperature

Why is it important to have accurate measure of dry matter

so that the varying water is removed and to balance the rations accurately