Unit 5: Animal Nutrition
Chapters 15-17
Unit 5: Animal Nutrition
• Unit 5 Objectives:
– Basic understand of nutrients, digestibility,
evaluation, and composition of feeds
– Knowledge of digestibility in both the
monogastric and ruminant animal
– Appreciation for nutrient function and
requirements for growth, maintenance,
reproduction, and lactation
– Understanding of ration formulation
Unit 5: Animal Nutrition
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Nutrients
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Any feed that functions to support life
Concentrates and roughages
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What are they?
What are the differences nutritionally?
Six basic classes
1.
2.
3.
4.
5.
6.
Water
Carbohydrates
Fats
Proteins
Minerals
Vitamins
Unit 5: Animal Nutrition
– Water
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Difference between water & moisture
Dry matter
Most important nutrient!
Functions
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Metabolic reactions
Transport nutrients
Temperature maintenance
Physical shape of the body (cell contents)
Unit 5: Animal Nutrition
– Carbohydrates
• Found in plant & animal tissue
• Simple carbohydrates
– Starch
» Easily digested
» High in energy
• Complex carbohydrates
– Cellulose, lignin
» Energy source
» Present in cell walls
Unit 5: Animal Nutrition
– Fats
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Includes oils
A.K.A. lipids
Fats are solid, oils are liquid at room temp.
2.25x more energy/lb. than carbs.
>100 fatty acids identified
– Linoleic, and α-Linolenic are essential in livestock diets
» Precursor of prostaglandins & cell structure
Unit 5: Animal Nutrition
– Proteins
• Simple
– Amino acids
» Building blocks of the animal’s body
» Ex.
• Complex
– Glycoproteins
– Lipoproteins
– Hemeproteins
• Only nutrient class that contains nitrogen
– Ave. ~16%
– 6.25 multiplier
» %N X 6.25 = %protein
Unit 5: Animal Nutrition
• Essential Amino Acids
– Must be supplemented in the diet
» Feed
» Microbial protein
• Nonessential Amino Acids are synthesized by the
body
• Various absorption rates
– Egg
– Animal
– Plant
Unit 5: Animal Nutrition
– Minerals
• Chemical elements other than carbon, hydrogen,
oxygen, nitrogen
• Macrominerals
– Required in larger amounts
– Ex.?
– Important for several major bodily functions
• Micromineral
– Trace minerals, required in small amounts
– Ex.?
– Important for vitamins, hormone synthesis
• Usually work together w/ other nutrients
• Can be harmful in high levels
Unit 5: Animal Nutrition
– Vitamins
• Organic nutrients required for very specific bodily
functions
• 16 vitamins
– Fat soluble
» A, D, E, K
– Water soluble
» C, B12, B1, Niacin
» In ruminants, these are synthesized by the
microorganisms
Unit 5: Animal Nutrition
• Feed Analysis
– Proximate Feed Analysis
• Separates feed components into group according
to feed value
• Accuracy of the analysis is dependent upon
accuracy of the sample
– Components measured
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Water
Crude protein
Crude Fat
Crude Fiber
Nitrogen-free extract
Ash (minerals)
Unit 5: Animal Nutrition
• Determining moisture and/or DM content
• Feed Digestibility
– Amount of a feed that is absorbed from the digestive
tract
– Great variance
– Measuring digestibility
• Energy Evaluation of Feeds
– Energy is available in any nutrient with carbon
• Carbs., protein, fats
– Driving force in bodily function
Unit 5: Animal Nutrition
– Measuring energy
• TDN
– Not as accurate
• ME
– Very accurate
– NE
– DE
– Calorie (cal)
• Energy required to raise the temp of 1g of water 1
degree C
Unit 5: Animal Nutrition
– Kilocalorie (kcal)
• Energy needed to raise the temp of 1kg water 1
degree C
– Megacalorie (Mcal)
• =1,000 kcal or 1,000,000 cal
– Some energy is lost, and therefore not
digested
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Feces
Urine
Gases
Heat
Unit 5: Animal Nutrition
• Animal uses energy in two ways
– Maintenance
– Production
• GE
– Amount of heat (cal) released from complete burning of a
feed (Bomb Calorimeter)
• ME is what the animal actually has the opportunity
to use
– NE is what is available after energy used for
consumption, digestion, metabolism (heat increment)
Unit 5: Animal Nutrition
•
In diet formulation:
– NEm
– NEg
– NEl
•
Feeds and Feed Consumption
– Classification of Feeds
1. Dry roughages & forages
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Hay
Straw
Other
2. Range, pasture, green forage
Unit 5: Animal Nutrition
3. Silages
4. Energy Feeds
•
>18% CF, <20%CP
5. Protein supplements
•
>20% CP
6. Mineral supplements
7. Vitamin supplements
8. Nonnutritive additives
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Antibiotics
Coloring
Flavors
Medicants
Etc.
Unit 5: Animal Nutrition
– Nutrient Composition of Feeds
• Goal of nutrient analysis is to predict the
production capability of a feed
• Tables are an average, true analysis is much more
accurate
– Composition can vary:
» 15% in CP
» 10% in energy
» 30% in minerals
Unit 5: Animal Nutrition
• Digestion & Feed Absorption
– Digestion
• Mechanical
• Chemical
• Role is to produce feed particles the can be
absorbed and used by the body
• Carnivorous, Omnivorous, and
Herbivorous animals
– Which is which?
Unit 5: Animal Nutrition
– Carnivores & Omnivores are monogastric
animals
• One, simple stomach
• Also some herbivores (horse, rabbit)
– Herbivores
• Ruminants
• Stomach compartments
Unit 5: Animal Nutrition
• The Monogastric Digestive Tract
– Mouth
• Mechanical chewing and swallowing of food
• Salivary Glands
– Esophagus
• Delivery tube from mouth to stomach
• Valve controls opening
– Stomach
• Primary area of reduction in feed particle size
Unit 5: Animal Nutrition
– Small intestine
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Duodenum
Jejunum
Ileum
Split molecules & absorb nutrients
– Large intestine
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Cecum
Colon
Absorb water
Forms indigestible waste (Feces)
Unit 5: Animal Nutrition
• Ruminants
– Rumen
• Fermentation vat
• Papillae
• Bacteria & protozoa
– Reticulum
• Aka honeycomb
• Initiate mixing in rumen
Unit 5: Animal Nutrition
– Omasum
• Many folds (manyplies)
• Grinding action?
• Not a lot of digestive responsibility
– Abomasum
• True stomach
– Ruminants can rechew feed already
consumed for more thorough breakdown of
feed particles (Cud) known as rumination
– Elimination of gases by eructation
Unit 5: Animal Nutrition
• Digestion in Monogastrics
– Begins in the mouth
– Enzymatic reactions
• Organic catalyst that speeds a chemical reaction
without being altered by the reaction
• Stomach secretions
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HCl
Mucus
Pepsin
Gastrin
Unit 5: Animal Nutrition
– Mixture and some digestion occurs, resulting
in Chyme
– Amino acids, fatty acids, and
monosaccharides are available for absorption
– Two methods of absorption
• Passive
– Molecules diffuse from high concentration area to low
concentration
• Active
– Engulf molecules in villi, and transport them to
bloodstream or lymph
Unit 5: Animal Nutrition
– Liver function
• Metabolizes feed particles in bloodstream
• Detoxifies harmful substances
• Digestion in Ruminants
– Fermentation in rumen & reticulum
• Microorganisms number in the billions
• Excess are removed with feed movement and
killed by acid in the abomasum
• Mutually beneficial relationship
Unit 5: Animal Nutrition
– Digestion is the same after feed reaches the
abomasum
– Microorganisms use starch and sugar for their
growth and development
• Robs the animal of valuable energy sources
• Produce Volatile Fatty Acids (VFA) which the
animal absorbs and converts to energy
– Acetic
– Propionic
– Butyric
• Methane gas is released through eructation
– What if this action fails?
Unit 5: Animal Nutrition
– Esophageal groove
• Pathway directing milk to abomasum
– Complete function of digestive tract is not
complete until:
• Sheep ~2 mos.
• Cattle ~3-4 mos.
• Influenced by feed type
– Energy Pathways
• End products of glucose and fatty acids supply
body tissues with energy, and become milk fat and
lactose in the lactating ruminant
Unit 5: Animal Nutrition
• Primary organs and tissues in energy metabolism
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Rumen
Abomasum
Small intestine
Liver
Blood vessels
Mammary gland
Body tissue
• Undigested energy products
– Complex carbos. (lignin) and other (ex. Ketone bodies)
– Excreted through large intestine or kidneys
Unit 5: Animal Nutrition
– Protein Pathways
• End products of protein and NPN:
– Amino acids
– Ammonia
» Excess formed into urea in liver and excreted in the
urine
» Some is returned to the rumen
– Synthesized amino acids
Unit 5: Animal Nutrition
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Nutrient Requirements for Body
Maintenance
– No gain/loss of weight or production
– High priority for nutrients
1.
2.
3.
4.
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Body tissue repair
Temp control
Energy for vital organ function
Water balance maintenance
Takes ~½ of all ingested feed
Unit 5: Animal Nutrition
– Examples
• Feedlot steers ~30-40% for maintenance
• Breeding animals ~90%
• 100# dairy cow eat 4-5x their daily maintenance
requirement
– Body size & Maintenance
• Increased body size means increased nutrient
requirement
• But, not at a linear rate
Unit 5: Animal Nutrition
• Nutrient Requirements for Growth
– Occurs when:
• Protein synthesis is > protein breakdown
• Cells increase in number & size
• Both
– Building of muscle, bone, connective tissue
– Nutrients needed for growth
• Energy, protein, minerals, vitamins
– Muscle growth is due to protein
Unit 5: Animal Nutrition
– Ca, P, & NaCl
• Ca usually plentiful in legume forage
• P plentiful in grain
– I & Se
• Deficiency in I results in goiter
• Se deficiency-white muscle disease
Unit 5: Animal Nutrition
– Vitamin D
• Needed for proper use of Ca & P
• Can get from sunshine (conversion of cholesterol
in the skin), unless raised inside
– Vitamin A
• Can be lost during drying in the sun, or extended
dry storage
Unit 5: Animal Nutrition
• Nutrient Requirements for Fattening
– Storing surplus feed in and around body
tissue
– Desirable for quality meat production and
energy storage
– 2.25x more energy to produce 1# fat as
opposed to 1# protein
– Due to excess:
• carbos, fats, protein
Unit 5: Animal Nutrition
• Nutrient Requirements for Reproduction
– 2 categories
• Gamete production
– Nothing above normal maintenance
– Body condition affects fertility
• Fetal growth
– Greatest in last trimester of pregnancy
– Requirements of the fetus are the same as those after it
is born
– Healthy females can withdraw nutrients from their body
for the fetus
Unit 5: Animal Nutrition
• Nutrient Requirements for Lactation
– Requires protein, minerals, vitamins, energy
– Protein is greatest
• >3% protein in milk
• Body protein can be mobilized in deficient times
– Ca & P are critical
• Hypocalcemia
Unit 5: Animal Nutrition
– Energy
• Based on amount of milk produced
• Production can be limited by intake
– High producing dairy cow may need 3-4x the energy of
non-lactating cow of same size
• Why do some cows continue to lose weight?
• What is the ideal forage to concentrate ratio in
dairy cows?
Unit 5: Animal Nutrition
• Energy Requirements for Work
– Primary requirement is energy
– Regular exercise schedule is necessary for
good health
• Perspiration removes nitrogenous wastes
• Ration Formulation
– Objective is to economically match the
animal’s nutrient requirements with available
feeds
Unit 5: Animal Nutrition
– Things to consider:
• Palatability
• Physical form
• Other
• Diet Modification to Minimize N & P
Pollution
– Impacts air & water quality
Unit 5: Animal Nutrition
–N
• By-product of protein digestion
• What does it affect?
–P
• Mineral nutrient
• Will be excreted if fed in excess
– Two concerns
• Volatility of N in the form of ammonia
• Distribution of manure nutrients
– P contaminates surface water
– N contaminates groundwater
Unit 5: Animal Nutrition
• Unit 5 Assignment
– Chapter 17 review questions
– Pg. 312
• Review next time
• Exam 2 next Tuesday?