Analysis in Nutrition Flashcards
(37 cards)
What two main approaches are used to assess nutritive value of feeds?
- Laboratory assessment
- chemical analysis
- NIR
- in vitro digestion
2.animal assessment
- in vivo
What are the six classes of nutrients?
- water
- carbs
- proteins
- fats and fatty acids
- minerals
- vitamins
Describe proximate analysis.
Proximate analysis is always on a dry matter (DM) basis. (meaning it’s water free)
It determines protein, fat, fiber, organic matter (used to find ash), and nitrogen free extract.
How can dry matter and moisture be measured?
The ground sample is weighed, and dried until stable, then weighed again. (ex. oven, microwave, etc.)
This process is repeated until no weight change occurs.
What is the difference between dry matter and as fed basis?
As fed basis includes moisture while dry matter does not.
Feed is bought, sold, and fed on an as fed basis.
Nutrients are contained in the dry portion of the feed, and moisture content is variable.
Nutritionists normally balance diets based on DM and use it for feeding conversions. Water left behind can hinder other analyses.
How is DM calculated?
% DM = weight of feed after drying/weight of feed prior to drying x 100
What is crude protein?
The nitrogen content of the feed x 6.25.
Proteins are 16% N by weight, so 100/16 = 6.25
What animals need higher protein requirements?
Younger animals need a higher percent protein in their diet because of their rapid tissue growth and low feed intake.
What do protein requirements change with?
Age
Body Size
Level/Stage of production
Growth
Intake
Why does protein requirement change with body size?
The actual amount of protein intake in grams increases as body size increases, so the gram requirement increases.
How does level of production affect protein requirement?
Animals growing faster or milking more than their counterparts have a higher gram protein requirement.
What is included in crude fat?
Crude fat, aka ether extract, includes waxes, pigments, ether, etc.
What does crude fiber include?
Components of the cell wall, mostly cellulose.
What is crude ash?
The mineral content of the feed.
It is found by weighing a sample, incinerating it, and weighing the remaining inorganic material.
What is NFE?
Nitrogen free extract
It includes starch, soluble fibers, and sugars
How is NFE determined?
NFE = DM - CP - CF - EE - Ash
List all the categories of proximate analysis.
- Water
- Ether extract (crude fat)
- Crude fiber
- Crude protein
- Ash
- NFE
What is the Van Soest System?
This is a system developed by Peter Van Soest to better account for the fiber content. He did not agree with how Proximate Analysis divided carbs into crude fiber and NFE.
Is is also known as the detergent system.
The two types are Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF)
What does NDF include?
cellulose, hemicellulose, pectin, and lignin
What does ADF include?
cellulose, pectin, and lignin
How are proximate analysis and Van Soest integrated?
Proximate analysis is used to find DM, ash, EE, and CP.
Van Soest is used to find NDF in ADF as opposed to crude fiber and NFE.
What is NFC?
Non-fiber carbohydrates, the method used in the Van Soest system. It is not NFE.
Calculated as follows:
NFC% = 100 - (CP + NDF + EE + Ash)
It relies on NDF
Summarize the differences between NFC, NFE, and NSC.
NFC = non fiber carbohydrates, it relies on NDF
NFE = nitrogen free extract, uses CF, not NDF
NSC = non-structural carbohydrates, analyzed components (sugars, starches)
What is the most digestible fraction of the cell wall?
hemicellulose
feeds with higher hemicellulose are more digestible
