Chapter 4: Analysis of Pet Food Composition (Hill) Flashcards
Gross energy (GE) *
the total energy content of food.
digestible energy (DE) *
energy intake (gross energy) - energy in feces
metabolizable energy (ME) *
energy intake (GE) - energy in feces, urine, and combustible gas
modified atwater factors for protein, fat, and carbs? What are they used for? ***
protein/carbs: 3.5
fat: 8.5
Used to calculate the ME density of pet foods
atwater factors for protein, fat, carbs? *
protein/carbs: 4
fat: 9
average 8 oz. cup contains about __g of an average dry diet *
90g
metabolizable energy density (kcal/g) is best obtained from: *
feeding trials. Average for canned food = 1 kcal/g; dry food: 4 kcal/g
is “95% fat free” low fat? *
NO. When you remove water, can be >40% calories from fat.
____ determines how much of a diet an animal needs to eat *
energy density
why do high fiber diets make %DM useless? *
high fiber diets have higher protein to make up for less carbs and animal has to eat more to meet energy requirements, thereby consuming more protein
NFE = ***
nitrogen free extract; Estimates carbohydrate by difference:
100 - (moisture + protein + fat + ash + crude fiber)
This is known as a “proximate analysis (% as fed)”
methods of stating pet food composition
% as fed (includes moisture)
% DM (excludes moisture, used in ruminants)
Relative to ME
disadvantage of as fed analysis
comparison of canned, dry and semi-moist diets difficult b/c of variable moisture content
We should eat less than __% kcal as fat
30
disadvantage of dry matter analysis
doesn’t allow comparison of diets w/ different energy densities (energy density differs if the fat or fiber content differs b/w diets)
Which parts of GA are presented as maximums?
crude fiber, moisture
which parts of GA are presented as minimums?
crude protein, crude fat
average analysis
represent better estimate of what is in food than guaranteed analysis and is required on Euro labels
How to determine ME Intake (kcal/day)? *
ME density (kcal/g) x weight consumed (g/d)
disadvantage of using modified atwater factors *
don’t allow for differences in digestibility of diets. They tend to underestimate the digestibility of fat and overestimate the digest. of carb in high fiber diets. Therefore, they underestimate ME in digestible high fat diets and overestimate digest. in poorly digestible high fiber diets
calculation of %DM from an As fed analysis:
%DM of a nutrient = (% nutrient as fedx100/%DM of food) = (%nutrient as fedx100/(100-%moisture))
ideal method for describing and comparing pet food composition
energy-based analysis.
- ME determines the amt. to feed
- only way to compare diets which vary widely in energy density
Before deciding whether a nutrition experiement is properly controlled, ….
convert all nutrient analyses to an energy basis for comparisons (w/n an energy-based analysis)
REVIEW TAKE HOME 1 CALCULATIONS
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