NUTR 3210 Lecture Notes - Lecture 2: Phospholipid, Vitamin K, Bacterial Growth
27 Jun 2018
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Digestibility
oMeasure of the fraction of a specific nutrient or of energy that is extracted by
the gastrointestinal (GI) tract
oAlso referred to as bioavailability
oMeasure by total collection and indicator methods:
Calculation of digestibility coefficient (apparent and true)
oCalculated from the amount of nutrient in the diet and the amount appearing in
the feces
oRepresents a combination of nutrient release from the food matrix, microbial
fermentation, and absorption
Total collection method
oAllow the animal to adapt to the diet over a 7-21 day period
oIsolate animal for quantitative analyses
oMeasure intake over a 3-10 day period
oCollect and weigh all feces
oAnalyze for nutrient of interest
oCalculate apparent digestibility coefficient (ADC)
o
limitations of the total collection method
oAccuracy in measuring food intake in animal studies? Extremely difficult because
animals tend to scatter around their food and feces
oMetabolic cages = anxious animals (diarrhea?) (metabolic cages -> collect and
analyze urine and feces)
oLabour intensive
oAnimals confined in costly equipment
oNot viable for captive wild animals
Indicator method
oAlso referred as the "marker technique." It requires that a specific component in
the food be identified as a marker. The marker can be:
Internal (a natural component of the feed)
External (a component added to the feed)
oCharacteristics of a good marker:
It should be non-absorbable, and move through the GIT uniformly
It must not alter gastrointestinal tract function
It must mix with the other food/feed components
It must be easily and accurately measured in feed and fecal samples
oCan determine the apparent digestibility coefficient (ADC)
Indicator method
oAdapt animal to test diet over 7-21 days (includes marker)
oCollect a feed and fecal sample
oAnalyze each for marker and nutrient of interest
o
A = ratio of nutrient/ marker in feed
B = ratio of nutrient/ marker in feces
Advantages of the indicator method
oLess labour intensive
oLess interference with natural habitat
oCan be used with wild animals
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Measure of the fraction of a specific nutrient or of energy that is extracted by the gastrointestinal (gi) tract o o o. Calculated from the amount of nutrient in the diet and the amount appearing in the feces o. Represents a combination of nutrient release from the food matrix, microbial fermentation, and absorption. Allow the animal to adapt to the diet over a 7-21 day period. Calculate apparent digestibility coefficient (adc) o o o o o o o limitations of the total collection method o. Extremely difficult because animals tend to scatter around their food and feces o. Metabolic cages = anxious animals (diarrhea?) (metabolic cages -> collect and analyze urine and feces) Not viable for captive wild animals o o o. It requires that a specific component in the food be identified as a marker. It should be non-absorbable, and move through the git uniformly. It must mix with the other food/feed components.
