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CHAPTERS 15-17
Unit 7: Animal Nutrition
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. Water2. Carbohydrates3. Fats4. Proteins5. Minerals6. Vitamins
Nutrients
Water Difference between water & moisture Dry matter Most important nutrient! Functions
Metabolic reactions Transport nutrients Temperature maintenance Physical shape of the body (cell contents)
Nutrients
Carbohydrates Found in plant & animal tissue Simple carbohydrates
Starch Easily digested High in energy
Complex carbohydrates Cellulose, lignin
Energy source Present in cell walls
Nutrients
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
Nutrients
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
Nutrients
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
Nutrients
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
Nutrients
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
Feed Analysis
Proximate Feed Analysis Separates feed components into group according to
feed value Accuracy of the analysis is dependent upon accuracy
of the sampleComponents measured
Water Crude protein Crude Fat Crude Fiber Nitrogen-free extract Ash (minerals)
Feed Analysis
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
Feed Analysis
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
Feed Analysis
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
Feed Analysis
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)
Feed Analysis
In diet formulation: NEm NEg NEl
Figure 15.3 Measures of energy and energy utilization.
Feeds and Feed Consumption
Classification of Feeds1. Dry roughages & forages
• Hay• Straw• Other
2. Range, pasture, green forage
Feeds and Feed Consumption
3. Silages4. Energy Feeds
• >18% CF, <20%CP
5. Protein supplements• >20% CP
6. Mineral supplements7. Vitamin supplements8. Nonnutritive additives
• Antibiotics• Coloring• Flavors• Medicants• Etc.
Feeds and Feed Consumption
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, & 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
The Monogastric Digestive Tract
Small intestine Duodenum Jejunum Ileum Split molecules & absorb nutrients
Large intestine Cecum Colon Absorb water Forms indigestible waste (Feces)
Figure 16.1 Digestive tract of the pig as an example of the digestive tract of a monogastric animal.
Figure 16.2 Digestive system of the horse. The posterior view shows the colon or large intestine proportionally larger than the rest of the digestive tract. Note particularly the location of the cecum at the anterior end of the colon.
Ruminants
Rumen Fermentation vat Papillae Bacteria & protozoa
Reticulum Aka honeycomb Initiate mixing in rumen
Ruminants
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
Figure 16.4 Beef cattle digestive tract.
Figure 16.5 Lining of the four compartments of the ruminant stomach (goat). (A) Compartments intact.(B) Compartments separated. Courtesy of George F. W. Haenlein. University of Delaware.
Figure 16.7 The esophageal groove, with its location relative to the esophagus, reticulum, and rumen. Courtesy of N. J. Benevenga et al., 1969. Preparation of the ruminant stomach for classroom demonstration. J. Dairy Sci. 52:1294.
Digestion in Monogastrics
Begins in the mouthEnzymatic reactions
Organic catalyst that speeds a chemical reaction without being altered by the reaction
Stomach secretions HCl Mucus Pepsin Gastrin
Digestion in Monogastrics
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
Digestion in Monogastrics
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
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?
Digestion in Ruminants
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
Digestion in Ruminants
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
Figure 16.8 Energy pathways in the ruminant. Source: J. Bryant and B. R. Moss, Montana State University.
Digestion in Ruminants
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
Figure 16.9 Protein pathways in the ruminant. Source: J. Bryant and B. R. Moss, Montana State University.
Nutrient Requirements for Body Maintenance
No gain/loss of weight or production High priority for nutrients
1. Body tissue repair2. Temp control3. Energy for vital organ function4. Water balance maintenance
• Takes ~½ of all ingested feed
Nutrient Requirements for Body Maintenance
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 tissueNutrients needed for growth
Energy, protein, minerals, vitamins
Muscle growth is due to protein
Nutrient Requirements for Growth
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
Nutrient Requirements for Growth
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, energyProtein is greatest
>3% protein in milk Body protein can be mobilized in deficient times
Ca & P are critical Hypocalcemia
Nutrient Requirements for Lactation
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 qualityN
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