Nutritive Value of Feedstuffs Flashcards
What are some steps involved in determining nutritive value?
- Chemical Analysis (complete, proximate, Van Soest, NIR)
- Palatability
- Digestibility
What is a complete chemical analysis?
This test examines every nutrient in a feed, and takes a long time.
What is a proximate analysis and what does it determine?
A proximate analysis determines the following factors in feedstuffs:
- Water
- EE
- CF
- CP
- Ash
- NFE
How is water content determined in a proximate analysis?
by drying the sample
What is EE?
EE is ether extract, or crude fat. It’s simply a measurement of crude fat.
What is CF?
CF is crude fiber, and it measures cellulose, lignin, and hemicellulose content.
What is CP?
CP is crude protein, an estimate of the protein content of a feed based on the nitrogen content. It is found by multiplying the %N in a feed by 6.25.
What is ash?
Minerals; the inorganic residue left behind after burning food
What is NFE?
NFE is Nitrogen-Free Extract, and it is obtained mathematically. It consists of mostly sugars and starches.
What is the Van Soest method?
This method analyzes fibers in feed.
Acid Detergent Fiber
Neutral Detergent Fiber
What is the Acid Detergent Fiber (ADF)?
This measurement contains cellulose and lignin, and is usually associated with digestibility. Since it contains more non-digestible contents, a high ADF is bad.
What is the Neutral Detergent Fiber (NDF)?
A measurement containing cellulose, hemicellulose, and lignin; it indicates intake, or the amount an animal may consume. The NDF is always a higher number than the ADF.
What is NIR?
NIR is Near Infrared Spectroscopy. It is a rapid method that uses IR light to analyze bonds in feeds and determine moisture, fat, protein, etc.
Define palatability
the fact or quality of being acceptable or agreeable to the taste; will the animal eat it?
What are some limitations to chemical analysis, Van Soest method, and NIR?
They don’t tell us anything about palatability, toxicity, or digestibility.
Define digestibility
The ability of a nutrient to be digested and absorbed by the animal rather than be eliminated in the feces.
Describe a digestion trial
An animal is given a feed, and if it does not exit in the feces, it is considered digestible
How is the Apparent Digestion Coefficient (ADC) calculated?
D/C = weight of nutrient consumed - weight of nutrient excreted in feces/ weight of nutrient consumed
example: an animal eats 12 grams of feed dry matter and excretes 6 grams of feed dry matter in its feces. What is the feed’s ADC?
(12-6)/12 = 0.5 ADC
What factors influence digestibility?
fiber content, rates of passage, preparation, and processing
What is the easiest way to alter a feed’s digestibility?
Altering the fiber content of the feed
higher fiber content is harder to digest, especially in monogastrics
What is TDN?
Total Digestible Nutrients: an estimate of energy content in a feed, it does not really measure digestion
What is the significance of CP?
CP (crude protein) can be used to find the N content of a feed and vice versa using the conversion factor of 6.25
How much more energy do lipids contain than carbs or proteins?
2.25 times more energy
What is GE?
Gross Energy, the total energy in the feed, and always the highest number when estimating feed energy
What is bomb calorimetry and what does it measure?
It is a type of measurement that burns feed to determine the energy released, and it measures the GE of a feed
What is DE and how is it calculated?
DE is Digestible Energy, it measures the energy absorbed in the GI tract
DE= GE - FE
What is FE?
Feces Energy
What is UE?
Urinary Energy