Lecture quiz 5/5/23 (Friday) Flashcards
What are the five types of specialized analytical methods in chemical evaluation?
gross energy analysis
amino acid analysis
mineral analysis
vitamin analysis
fatty acid analysis
What is gross energy analysis (bomb calorimetry)
- measured by burning a sample of the feed in a bomb calorimeter and measuring the heat produced
In gross energy analysis, what is the basic unit of energy called?
calorie (cal) which is the amount of heat required to raise the temperature of 1 g of water by 1C
this unit is too small for use in livestock, energy content of feeds is usually expressed as kilocalories (kcal) or megacalories (Mcal)
1000 cal = kcal
1000,000 cal = 1 Mcal
Cal = kilocalories for humans
which nutrient contains the most gross energy?
energy releassed from different nutrients (bomb calorimeter)
- carbohydrate (starch, fiber, sugars) -> 4.2 Kcal/g
- fat = 9.45 Kcal/g
- protein = 5.7 kcal/g
- Ash = 0.0 kcal/g = does not generate energy
- water and ash cant be burned = materials that cannot be burned does not have any energy
what is gross energy?
- little of direct value for evalutaing feedstuffs.
- starting point in feed energy evaluation systems
what is Near - Infrared- Spectroscopy (NIRS) ?
- rapid and cost effective alternatives to traditional wet chemistry analysis of feed samples
- feed sample is placed in a NIR instrument with a built-in computer.
- computer compares the reflectance to a database of feed samples
what estimates the “most likely” values for moisture, DM, fat, protein, NDF, ADF, ash, energy content, and some minerals
NIRS
what is the disadvantage of NIRS?
only be accurate as the database and calibration behind it.
What is biological evaluation?
- needs participants (animals)
- use of animals to measure utilization of nutrients from a feedstuff or diet.
what are the common methods for biological evaluation?
- feeding trials
- Digestion or metabolism trial
- feed energy evaluation system
what is a feeding trial?
determines the palatability of feedstuffs and their effect on feed and animal performance.
ex:
growth, weight gain, milk yield, egg production, etc
what is the more technical method of biological evaluation?
digestion or metabolism trial
Feeding trial
- measure feed intake and the output produced (weight gain, quantity of milk or eggs)
- with measures of intake and output one can them measure efficiency of feed utilization
- beef, swine, fish, and poultry industries use feed efficiency (feed to gain ratio) as a bench mark for profitability
what is FCR?
feed consumption ratio
fcr = feed consumption/ body weight gain
