Intro Flashcards
Define nutrition
Qualitative and quantitative needs from the diet to maintain good health or production
*involves all essential nutrients and balanced macro and micronutrients
Define nutrient
Any chemical compound that is needed from diet to maintain life and good health
Define food
Edible material that provides nutrients (used for humans and small animals)
Define feed
formulated whole diets for non-humans
What is a proximate analyses?
Analytical methods to assess feedstuffs
Components of proximate analysis
- moisture
- Dry matter
How are fat and protein separated from dry matter?
Fat= ether extraction gives ether extract (EE)
Protein= Kjeldahl procedure gives crude protein
How is protein measured in the diet?
Crude protein- supplied by determining the amount of Nitrogen (because its role in amino acids)
How do you analyze fiber content?
-Boil in acid and then boil in alkali= Crude Fiber and Ash (inorganic/minerals)
What are the components of dry matter?
- organic material (protein, fat, carbohydrates, vitamins)
- Inorganic or ash material (minerals)
How do animals get their Biological energy?
Organic substrates (fat, protein, carbohydrates, etc.) are oxidized to CO2 and H2O through a series of enzyme catalyzed reactions producing ATP
Energy requirements
Substrates that can be used for energy production are interchangeable and not actually required by the animal
*preferred type depends on life stage, and type of animal
Energy substrate components
-carbohydrates
-lipids
-amino acids
Kilocalorie
Energy required to raise the temperature of 1kg of water by 1 degree C
**Calorie in human nutrition is a kcal
**Joule is used in Europe (1 calorie=4.18joules)
What two ways can energy content of food/feed described?
- Energy Partitioning
- Nutrient-ATP based-modelling
Energy Partitioning
Depends on how much energy is within the food, how much is available for the animal to use, and how we can measure it
-We oxidize (burn) it and measure how much heat it gives off
Bomb Calorimetry
Measures the gross energy of a feedstuff
-Gross Energy is heat released when CHO, lipids, proteins in feedstuff are burned off
Bomb Calorimetry calculation
Feed + O2 = CO2 +H2O + Heat
How is Bomb Calorimeter used?
-Material combusted inside bomb calorimeter
-Box is sealed with oxygen atmosphere
-Burnt material heats the water
-Energy change is found from temp change of water
-Constant volume, not constant pressure, so gives change in Energy
Gross Energy
The amount of heat released when a substance is completely oxidized in a bomb calorimeter
GE=heat of combustion
Limitation of Gross energy
- GE indicates very little about nutritional value of a feed to an animal
Eg. Corn grain and wood have similar GE (4.40kcal/g compared to 4.50)
- Need to account for losses of energy (check poop!)
Fecal energy
Some feed energy is not absorbed and instead is lost in feces due to incomplete digestion
Therefore FE= energy contained in feces measured using bomb calorimeter= single largest loss of ingested energy
Digestible Energy
= Gross Energy- Fecal energy
Digestibility percentage
= (DE/GE) x 100
Can you assume that all of the energy in feces comes from the food?
No because there are bacteria that can be producing some energy
What is contained in the feces?
-water
-unabsorbed feed dry matter
-Bacteria
-sloughed gut epithelial cells
-digestive enzymes
Apparent digestible energy
-Varies. May sometimes underestimate and other times overestimate true energy value
When is Digestible Energy often used?
-widely used in pigs and finfish
