Animal Nutrition
Topic 3043
Carbohydrates and Fats
Digestion, Absorption and Feed
Consumption
Anna Blight
Carbohydrates and Fats
• The primary energy source in feed
Carbohydrates
• Contains carbon, hydrogen and oxygen
• Digestion breaks down carbohydrates
into simple starches and sugars
Carbohydrates
• Sugars and starches are a very
important source of energy
• Roughages are an important source for
starch in ruminant diets (hays and
silage, etc.)
Carbohydrates
• Monogastrics better utilize concentrates
(cereal grains, oil meals, soybean
meals, etc) as source of carbs.
• Concentrates are high in energy
• Low in fiber
• Highly digestible
Fats
• Primary energy source
• Contains carbon, hydrogen and oxygen
• Digestion breaks down fat into fatty
acids
• 2.25 times more energy / pound than
carbohydrates
Digestion and Absorption
• The role of digestion is to reduce
feed particles to molecules
• Molecules can be absorbed into the
blood and eventually support body
functions
Digestion and Absorption
• Digestibility refers to the amount of various
nutrients in a feed, which can be absorbed
from the digestive tract
• Animals are classified as ruminants or
monogastrics
Ruminants
• Cows, goats and sheep
• Rumination = Chew cud
• (re-chew a regurgitated bolus of feed)
Ruminants
• Has a complex stomach consisting of
more than one compartment
• The four compartments are called
rumen, reticulum, omasum and
abomasom.
Ruminants
• The rumen is a large fermentation vat
where bacteria and protozoa thrive and
break down roughages to obtain
nutrients for their own use.
• Animal has mutualistic relationship with
microorganisms
Cattle synthesize B vitamins
• Microorganisms in the gut make
B-complex vitamins
• Can also make some proteins if given
correct type of nitrogen
• Later these microorganisms are
digested in the small intestine to
provide nutrients for the animal’s use
Fermentation process
• Microbial fermentation of carbohydrates
produces volatile fatty acids as waste
products
• Animal uses volatile fatty acids as major
source of energy
• Also produces large amounts of
methane gas and some carbon dioxide
Monagastrics
• Pigs, horses, poultry and humans
• Simple stomach, one compartment
• Enzymes present in saliva and in the
stomach aid in digestion
Monagastrics
• Carbohydrates break down into simple
starches and sugars
• Proteins to amino acids
• Fat to fatty acids
Monogastrics
• Cannot significantly synthesize
B-complex vitamins or amino acids
• Small intestine receives finished
products of digestion
• Small intestine is most important area
for digestion and absorption of feed