Animal Nutrition: Feed Analysis
How is fatty acids content estimated?
%EE - 1=Fatty acid %
What are the limitations of proximate analysis?
1) Crude fiber underestimates fiber because some hemicellulose and lignin are removed 2) Ether extract measures non-nutritive components (wax, pigment) and overestimates fat and energy 3) Crude protein measures components not all animals can utilize 4) No specific vitamins or minerals
In what two ways are animal diets described?
1) Feed ingredients 2) Nutrient composition
Why is it better to compare feed on a "dry-matter basis"?
1) water content varies dramatically 2) Allows nutrient comparison amongst feeds
What is near infrared analysis?
A machine that calculates components of feed based on light absorbed, must be calibrated
What is ADL?
Acid detergent lignin, calculated by treating ADF with sulfuric acid
Why would buffers be added to a diet?
Be fed with a high grain diet to prevent acidosis
How is organic material calculated? And why is it important to know?
By difference, organic material is where energy comes from
How can loss of volatile compounds be reduced?
By frying samples at a lower temperature or by freeze drying
What does crude fiber measure?
Cell wall components, inaccurate because some hemicellulose and lignin removed in process
What is proximate analysis important for?
Diet formulation
What has ether extract been replaced by? Why is it not widely used?
Direct analysis of fatty acid composition, but it is expensive
What are the categories feed is broken into?
Dry matter and moisture content
What is silage?
Feed that is stored with a high moisture content and no air which allows feed to ferment and preserves it
What does 'as fed' mean?
Feed with moisture content
What feeds is ether extract not suitable for?
Forages, IS suitable for cereal grains
What is an ideal way to measure lipids?
Gas chromatography (too expensive, involves mobile and stationary phase)
What is hay?
Hay has reduced moisture which prevents fermentation and food does not spoil
What are cereal grains?
High in starch, low in fiber ex: corn, barley wheat
What is proximate analysis? What does it describe?
It describes 6 components of feed 1) Water (nutrient) 2) Ether extract (EE) (fat) 3) Crude fiber (CF) 4) Nitrogen free extract (NFE)(digestible carbs) 5) Crude protein (CP) 6) Ash (minerals)
How do you calculate how much to feed an animal?
It is the animals requirement divided by the percentage of the component in question
What is ash?
It is what is left after being burnt, it is inorganic minerals
What is ether extract and what are its downsides?
It is whatever is soluble in ether, used to calculate fat, but pigments and wax are ether soluble which overestimates energy
What is the biggest downfall of crude protein?
It only measures nitrogen, and not all animals can utilize all forms
What is the energy like found in roughages? What is the exception?
Low to moderate energy and protein, exception is legumes
What is Kjeldahl's method?
Measures nitrogen 1) Digest sample with sulfuric acid and ammonium sulfate 2) Distil sample, converts ammonium sulfate to ammonia 3) Titrate with boric acid
What replaced crude fiber and is more accurate? What needs to be further done to it?
Neutral detergent fiber Needs to be corrected for minerals and Nitrogen
What is NFE? How is it calculated? And what are sources of error??
Nitrogen free extract, digestible carbs, calculated by difference so if an error is made in another component it will greatly affect NFE
What is NFC? How is calculated and why is it more accurate?
Non-fiber carbs, measured by difference but using NDF not CF so there is no lining contamination
What is NSC?
Non-structural carbs, calculated chemically
What is a concentrate?
Nutrient dense mixture consisting of anything non forage
What is gluten?
Protein in corn, corn gluten meal is only protein
How are minerals and vitamins calculated?
Table values of averages, people usually just add more to feed
Why is ash somewhat irrelevant?
There are no requirements for ash, but there are for minerals
What are high fiber byproducts?
They are wastes from human food and cheap, low in energy high in fiber
What are protein supplements?
They contain at least 20% crude protein and have moderate to high energy ex. soybeans, canola, cotton seeds ex. meals (fish, blood, chicken)
What are pre-biotics?
They increase the quality of the food
Why are anitbiotics added to feed?
To keep the feed from spoiling and killing bacteria that may develop in it
Why aren't vitamins, minerals, and amino acids calculated??
Too expensive
What is citrus pulp?
Waste from citrus fruits, high energy byproduct because still contains some carbs
What is the only homogenous component of feed?
Water
How do you calculate moisture content? How is the process inaccurate?
Weigh sample and heat in oven and then weigh again, difference is moisture and what is left is DM Volatile compounds are lost in the process