E Partitioning & Use What are the main energy sources for monogastric animals?

What are the main energy sources for monogastric animals?

Glucose

amino acids

lipids (fatty acids LCFA)

small amounts of volatile fatty acids (VFA or SCFA)

What are the main energy sources for ruminants?

Volatile fatty acids (acetic, propionic, butyric acid)

amino acids

LCFA (lipids)

small amounts of glucose

How is the gross energy (GE) of feed determined?

Using a bomb calorimeter

What is the digestibility coefficient?

-proportion of feed energy that is digested

= Feed energy eaten – (Energy in faeces / Feed energy eaten)

What is ME content and how is it determined?

Metabolizable energy

-determined using calorimetry and empirical equations based on digestibility or chemical composition.

What is the equation for ME content in Australia?

= 0.016 DOMD

-DOMD = digestible organic matter in the DM (g DOM/kg DM)

What are the factors influencing energy partitioning? (5)

Diet composition

growth stage

product type

activity

stress

How does diet composition affect energy partitioning?

Differences in digestibility

VFA ratios

protein/energy ratios

How does stress affect energy partitioning?

Differences in digestibility, VFA ratios, and protein/energy ratios influence energy partitioning

How does stress affect energy partitioning?

Stress increases maintenance requirements, with heat reducing intake and cold increasing heat production through metabolic cycles and shivering

Why do cattle fatten more efficiently on grain diets compared to grass diets?

Grain diets have higher propionic acid, which is glucogenic, providing more glucose for lipid production

What is fasting heat production (FHP)?

Heat produced at fasting, measured by calorimetry, representing basal metabolic rate

What is metabolic weight (MW or W^0.75)?

A way to equate species and account for differences in weight between growth stages

How does activity affect energy partitioning in dairy cows?

Activity increases maintenance requirements, with walking reducing milk production by 0.5L/km

What are the expressions of energy requirements?

Maintenance (liveweight maintenance) and production (meat, milk, wool, pregnancy)

What is the NRC equation for calculating GE for cats and dogs

GE = 5.7 × g protein + 9.4 × g fat + 4.1× (g NFE + g fiber)

What is the relationship between ME and maintenance?

ME is partitioned toward maintenance to power bodily processes that enable liveweight maintenance.

What is the role of NADPH in energy partitioning?

NADPH is needed for acetyl-CoA to fatty acid conversion, sourced from the pentose phosphate pathway during glucose metabolism

Digestibility coefficient?

Proportion of feed energy that is digested

Digestibility % equation

=(intake-fecal output)/intake x 100

equation ME

= 0.17 DM % - 2.0