ANS 3200 Exam 2 - Energy Systems and Feedstuffs

feed cost represents __________ of production costs (percent)

50-70%

average FCR of beef cattle

6:1

why do ruminants have a high maintenance energy requirement?

large rumen fermentation requires a LOT of resources

fixed formulation

ingredients are exact same with every diet, but nutrient composition is different; common in pet food industry

least cost formulation

ingredients change based on price, ingredients change but nutrient composition is the same

Gross feed efficiency

live weight gain per intake; higher number is better

feed conversion ratio

feed intake per live weight gain; lower number is better

purpose of determining digestibility

quantify available nutrients and energy concentration of ingredients/feedstuffs

components of measuring digestibility

accurate feed intake, fecal output, appropriate diet samples

digestibility trials

use of metabolism stalls, allows for accurate feed intake and fecal collection

adaptation period

first 10-14 days to help adapt digestive tract to new diet

isocaloric

same amount of energy per animal

isonitrogenous

same amount of nitrogen per animal

collection period

3-7 days

Apparent Total Tract Digestibility

simple feces collection; doesn’t account for endogenous losses, includes fermentation in large intestine

Apparent ileal digestibility

measures apparent absorption at terminal ileum; avoids fermentation of nutrients in large intestine; does not account for endogenous losses

Standardized ileal digestibiltiy

common for amino acid digestibility in swine, same process as AID; some are fed protein-free diet to quantify basal endogenous losses

slow rate of passage results in _________ and _________________

high fermentation; putrefactive compounds

high rate of passage results in __________________

incomplete digestion

metabolism trials

accounts for losses with urine; more precise measure of nutrient retention

TDN

do not include ash; determine digestibility of each component and add together; equivalent to DE

limitation of TDN

errors in chemical analysis; errors in sample collection; doesn’t account for energy losses in metabolism or heat increment

gross energy

total potential energy, measured with bomb calorimeter; fat>protein>carbs

water, ash, and vitamins have _______ energy.

NO

Digestible energy

GE-fecal loss

fecal energy losses

undigested nutrients, endogenous losses, ruminants > monogastrics

Metabolizable energy

DE - urine energy loss - gas energy loss; calculated in neutral growth animal

components of metabolizable energy

urine and combustible gases

Net energy

ME - heat increment; energy completely useful to animal for maintenance and production

heat increment

energy lost as heat due to energy costs of digestion and metabolic processes

net energy system

standard in cattle and used to predict daily gain and feed costs

NEm requirement

zero gain or loss of energy from body tissues; energy needed for basal metabolic activities and body temp regulation

determining NEm

direct calorimetry; animal placed directly in calorimeter and measures heat produced from animal

NEp

net energy remaining after maintenance is met

NEg is used _______ efficiently than for maintenance

less

NEl is used __________ as maintenance

just as efficiently

energy requirement for lactation considers:

amount of milk produced and fat percentage of milk produced