Chapter 8 Flashcards
Determination of nutrient value is important why?
Not all feeds are equal
Nutrient composition- crude protein, minerals, vitamins, energy
Economics
Cost of production and crude protein
Proximate analysis
Chemical procedure
Set of chemical/analytical procedures developed in Weedne, Germany over 100 years ago
Procedure to estimate nutrient composition
Proximate analysis estimates?
H2O Crude protein Ether extract Ash - mineral content Crude fibers Nitrogen free extract
Dry matter
Estimates water Measured water content of feed Heat jn drying oven at 55-105 c Weigh, dry, weigh Weight lost is water
More concerned with ruminants
Crude protein
Kjrldahl Methodology
Measure nitrogen content of sample
Protein contains on average 16% N
Simulate digestion in stomach and intestine
Okay for non ruminants but not ruminants
Fermentation - because ruminants have ability to ferment
Ether Extract
Measure lipid content
Weight sample, extract ether, weigh sample
What is lost is lipid
Fat is energy packed
Ash
Burn sample at 600 c
What is left is ash or minerals
Does not determine type
Nitrogen Free Extract
No standard procedure
NFE = 100- (%CP + %H2O + %EE + %CF + %Ash)
NFE = mainly CHO
PXA estimates
H2O Cp Ash Ee Cf NFE
Van soest method to describe forages
Ruminant nutritionist at Cornell
Cf not a good estimate for ruminants
Ruminants better use forages than non
Needed better system to describe forage than cf
Systems needed to consider - amount of fiber and fiber type
Fiber types
Hemicellulose
Cellulose
Lignin
Related to intake and digestibility
Neutral Detergent Fiber
Can be used to predict intake with ndf Feed with higher fiber tends to be bulky Hemicellulose Cellulose Lignin
Acid detergent fiber
Cellulose
Lignin
Predict digestibility it energy content
Lower digestibility and lower energy content
Chemical analysis
Atwater’s physiological fuel values
Assigns energy value to nutrient
Bomb calorimetry
Combust sample of feed
Heat given off - use H2O
Result = number of calories for combustion
Gross energy
