unit 5: animal nutrition chapters 15-17. unit 5: animal nutrition unit 5 objectives: –basic...

Unit 5: Animal Nutrition

Chapters 15-17


• 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


• Nutrients– Any feed that functions to support life– Concentrates and roughages

• What are they?• What are the differences nutritionally?

– Six basic classes1. Water

2. Carbohydrates

3. Fats

4. Proteins

5. Minerals

6. Vitamins


– Water• Difference between water & moisture• Dry matter• Most important nutrient!• Functions

– Metabolic reactions– Transport nutrients– Temperature maintenance– Physical shape of the body (cell contents)


– Carbohydrates• Found in plant & animal tissue• Simple carbohydrates

– Starch» Easily digested» High in energy

• Complex carbohydrates– Cellulose, lignin

» Energy source» Present in cell walls


– Fats• 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


– 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


• 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


– 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


– 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• Water• Crude protein• Crude Fat• Crude Fiber• Nitrogen-free extract• Ash (minerals)


• 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


– 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


– 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

• Feces• Urine• Gases• Heat


• 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)


• In diet formulation:– NEm– NEg– NEl

• Feeds and Feed Consumption– Classification of Feeds

1. Dry roughages & forages• Hay• Straw• Other

2. Range, pasture, green forage


3. Silages

4. Energy Feeds• >18% CF, <20%CP

5. Protein supplements• >20% CP

6. Mineral supplements

7. Vitamin supplements

8. Nonnutritive additives• Antibiotics• Coloring• Flavors• Medicants• Etc.


– 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


• 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?


– Carnivores & Omnivores are monogastric animals

• One, simple stomach• Also some herbivores (horse, rabbit)

– Herbivores• Ruminants• Stomach compartments


• 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


– Small intestine• Duodenum• Jejunum• Ileum• Split molecules & absorb nutrients

– Large intestine• Cecum• Colon• Absorb water• Forms indigestible waste (Feces)


• Ruminants– Rumen

• Fermentation vat• Papillae• Bacteria & protozoa

– Reticulum• Aka honeycomb• Initiate mixing in rumen


– 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


• Digestion in Monogastrics– Begins in the mouth– Enzymatic reactions

• Organic catalyst that speeds a chemical reaction without being altered by the reaction

• Stomach secretions– HCl– Mucus– Pepsin– Gastrin


– 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


– 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?


– 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


• Primary organs and tissues in energy metabolism– 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


– 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


• Nutrient Requirements for Body Maintenance

– No gain/loss of weight or production– High priority for nutrients

1. Body tissue repair

2. Temp control

3. Energy for vital organ function

4. Water balance maintenance

• Takes ~½ of all ingested feed


– 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


• 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


– 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


– 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


• 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


• 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


• 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


– 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?


• 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


– Things to consider:• Palatability• Physical form• Other

• Diet Modification to Minimize N & P Pollution– Impacts air & water quality


– 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 Assignment– Chapter 17 review questions– Pg. 312

• Review next time

• Exam 2 next Tuesday?

unit 5: animal nutrition chapters 15-17. unit 5: animal nutrition unit 5 objectives: –basic...

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