Unit 5: Animal Nutrition Chapters 15-17
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
• 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
Unit 5: Animal Nutrition
– Water• Difference between water & moisture• Dry matter• Most important nutrient!• Functions
– 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• 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• 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
• 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• 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• 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• Duodenum• Jejunum• Ileum• Split molecules & absorb nutrients
– Large intestine• Cecum• Colon• Absorb water• Forms indigestible waste (Feces)
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• Ruminants– Rumen
• Fermentation vat• Papillae• Bacteria & protozoa
– Reticulum• Aka honeycomb• Initiate mixing in rumen
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– 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– 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– 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
• 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
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?