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ANSC 318: EXAM 1
Definition of feed |
a material which, after ingestion by an animal is capable of being digested, absorbed and utilized. |
Definition of nutrient |
A component of a feed that aids in the support of life |
Nutrients |
Water and Dry Matter |
The organic parts of dry matter |
carbs, lipids, proteins, vitamins |
Which composition of feedstuffs (%) is usually the highest? |
Carbohydrate |
Which composition of feedstuffs (%) is usually low? |
Fat |
Which composition of feedstuffs (%) is variable? |
protein |
Which feedstuff composition (%) is the exemption for fat? |
Soybean meal, it is high in fat |
What composition of animal products (%) is low? |
Carbohydrates are low |
what composition of animal products (%) is high? |
Fat is usually high |
What composition of animal products (%) is variable? |
Protein is variable |
General Comments about Water |
it is often overlooked as a nutrient
essential nutrient to support: Metabolism and Temperature Regulation |
Sources of water include |
Drinking, contained in feed, metabolic |
How does forage moisture content effect water intake? |
As water intake (liters of water per kg of forage DM) will decrease as the moisture content of forage (%) increases. |
How does the level of production ans environment effect water requirements? |
As water intake (kg/day) increases so does temperature (C). |
General Comments about Carbohydrates? |
They are the main storage form of photosynthetic energy in plants
1:2:1 ratio of C:H:O
Comprise approximately 50 to 85% of the dry matter of typical animal feeds
The nutritive value os based upon the glycosidic bonds between sugar molecules |
Factors that affect the nutrient concentrations of feeds |
Location, management practices, soil fertility, climate, plant species, maturity of plant |
Methods used to evaluate feedstuffs |
Proximate analysis, Van Soest Analysis, Specific chemical analysis, NIRS, Animal-Based Methods, Microbiological methods |
Proximate Analysis System |
Most common, do not have to conduct a metabolism trial or feeding experiment, it is the basis for the total digestible nutrient (TDN) system. |
The Six different analysis used in the Proximate Analysis System |
Water
Crude Protein
Crude Fat (Ether Extract)
Ash
Crude Fiber
Nitrogen-free extract |
The weakness of the Crude Protein analysis |
not all protein contains 16% nitrogen
nitrogen analysis does not distinguish between non-protein nitrogen (NPN) (ex: urea & true protein). |
Primary weakness of proximate analysis system |
Separation of CHO into the CF and NFE is inaccurate and inconsistent
CF assay does not recover 100% of cellulose, hemicellulose, and lignin
some fiber components end up in the NFE fraction
Variation exists between plants in recovery of fiber components |
Components of Ash |
Macrominerals and Microminerals |
Components of Crude Protein |
Protein, Amino Acids, Amines(NPN), NPN. Nucleic Acids, Nitrates (NPN), B Vitamins |
Components of Crude Fat |
Fats, oils, waxes, organic acids, pigments, fat-soluble vitamins |
Components of Crude Fiber |
Cellulose, Hemicellulose, lignin |
Components of Nitrogen-free extract |
Sugars, starch, pigments, fructans, pectins, some cellulose, some hemicellulose, some lignin |
Background of Van Soest |
more accurate system to analyze CHO fraction
Uses detergents to solubilize various portions of plant material
replaced crude fiber analysis |
Neutral detergent fiber |
primarily cellulose, hemicellulose, lignin
total fiber or cell wall content in feeds
associated with feed intake potential, esp in the rumen
High NDF, low intake
Cellulose, Hemicellulose, Lignin |
Acid Detergent Fiber |
Consist primarily of cellulose and lignin
Highly associated with digestibility of forages
Feeds with high ADF, Less digestible and less energy
Cellulose, Lignin
|
Cell Contents (non-fiber components) |
Not a chemical assay
Calculated cell contents (DM)=100-NDF(DM)
Lipids, Sugars, Pectins, Soluble protein, starch, Water- soluble matter |
Why is NDF always higher than ADF? |
Due to the hemicellulose content. CF=NDF (ideally) |
Heat Damaged Forages |
Excess heat from bailing hay that is too wet can impair forage protein quality, as a result of Browning Reactions |
What is a Browning Reaction? |
Heat-induced chemical reactions between protein (amino acids) and sugars that render the protein to be less digestible |
What does ADF-CP analyze? |
A chemical assay used to measure heat-damaged protein. How much Nitrogen is bound to fiber (hemicellulose and cellulose). |
Background on the NIRS analysis |
Method of analysis to rapidly and reproducible measure the chemical components of feed samples with little or no sample preparation
Based on each major chemical component in a feed has a unique near infrared absorption spectrum that can be used to differentiate one chemical component from another |
Advantages of the NIRS |
fast, simple preparation, multiplicity of analyses with one operation, non-consumption of sample, high precision, environmentally friendly. |
Disadvantages of NIRS analysis |
Method is dependent of calibration procedures (main one), Doesn't work very well on minerals and vitamins, doesn't do well to analyse ration |
Chemical evaluation |
potential value of a feed can be measured by chemical analysis
actual or useful value of a feed to an animal can be determined only after making allowances for losses that occur. Digestion (enzymes/ferment), absorption (end products), and metabolism,. |
Nutrient Digestibility |
Digestibility of a feed is defined as that proportion of feed that is not excreted in the feces and is thus assumed to be absorbed by the animal. |