Animal Nutrition Mc Donald, Greehalgh and Warner. 1987. Animal Nutrition. Longman

Animal Nutrition

Mc Donald, Greehalgh and Warner. 1987. Animal Nutrition. Longman

دام تغذيه

Remember…

• Water

• Carbohydrates

• Lipids

• Protein

• Minerals

• Vitamins

WATER (H20)

Water (H2O)

• Overlook when formulating rations—assumed animals have access to good quality water– EXTREMELY IMPORTANT

• Cheapest & most abundant nutrient• May lose 100% of body fat, 50% of body protein

and live• Lose 10% of body water, dehydration occurs

and may result in death

Water (H2O)

• 65-85% of body weight at birth

• 45-60% of body weight at maturity

• Many tissues contain 70-90% water

Functions of Water

1. Transport of nutrients and excretions

2. Chemical reactions and solvent properties

3. Body temperature regulation

4. Aids in cell shape maintenance

5. Lubricates and cushions joints and organs

Sources of Water

1. Drinking water

2. Water in feed

3. Metabolic water

Sources of Water

1. Drinking– Pigs = 1.5-3 gal/hd/day– Sheep = 1-3 gal/hd/day– Cattle = 10-14 gal/hd/day– Horses = 10-14 gal/hd/day– Poultry = 2 parts water:1 part feed

Sources of Water

2. Water contained in feeds

• Highly variable in feedstuffs

• Grains = 9-30% water

• Forages– Hay <5%

– Silage 65-75%

– Lush young grass >90%

Calculating Water Content of Feedstuffs

• 100 lbs of silage (65% moisture) contains how much actual feed?

• 100 lbs * .65 = 65 lbs of water

• 100 lbs – 65 lbs = 35 lbs of feed

Sources of Water

3. Metabolic Water- Results from the oxidation of organic

nutrients in the tissues- 1 g of carbohydrates = .6 g of water- 1 g of protein = .4 g of water- 1 g of fat = 1 g of water

- May account for 5-10% of total water intake

Sources of Water Loss

• Urine

• Feces

• Lungs

• Skin

• Milk

Factors Affecting Water Intake

• Temperature & humidity

• Dietary factors

– High moisture feeds reduce drinking

– Fiber, DM intake, salt, and protein increase drinking

• Lactating vs dry

• Water quality

Water Absorption

• Readily absorbed – Monogastrics/Ruminants: Jejunum, Ileum,

Cecum, Large Intestine

– Ruminants: Rumen and Omasum

Dry Matter (DM)Bahan Kering (BK)

DM in the feeds or diets• DM content in feeds or diets• How to analyze ?• How to calculate ?• What is its effect on feed quality (nutrient content and

preservation)?• What kind of nutrients contained in the feeds or diets?• Remember !!!! − DM content and Feed Price?− DM content and Feed Handling?

Feeds or diets DM for animal

• DM content in feeds or diets for animal

• Function ?

• How to calculate ?

CARBOHYDRATES (CHO)

Carbohydrates (CHO)

• Primary component found in livestock feeds– 70% of DM of forages

– 80% of DM of grains

• Serve as source of energy or bulk (fiber) in the diet– Not ESSENTIAL nutrients

• Synthesized by animals

Carbohydrates (CHO)

• Definition: Hydrates of carbon formed by combining CO2 and H2O

– photosynthesis

Types of CHO

• Monosaccharides: 1 sugar molecule– Glucose

• Primary sugar body uses for fuel

– Fructose• Found in honey (75%), fruits, and cane sugar• Sweetest sugar

• Present in low concentrations in animal feedstuffs

Monosaccharide (Glucose)

Types of CHO

• Disaccharides: 2 sugar molecules linked by a glycosidic bond– Lactose (galactose + glucose)

• Milk sugar

– Sucrose (fructose + glucose)• Table sugar

• Present in higher concentrations in animal feedstuffs

Disaccharide (Sucrose)

Types of CHO

• Oligosaccharides: group of CHO consisting of 2-10 sugar groups

• Present in feed ingredients– Fructooligosaccharides (Inulin): present

Jerusalem artichokes– Galactooligosaccharides: present in

soybeans

Types of CHO

• Oligosaccharides– Not hydrolytically digested or digested

by the action of mammalian enzymes– Fermented by beneficial bacteria

present in GIT– “Functional Feed Ingredient”: foodstuffs

which, apart from their normal nutritional value, are said to help promote or sustain healthiness • PREBIOTIC

Soybean Oligosaccharides

Fructooligosaccharides (Inulin)

Types of CHO

• Polysaccharides: many sugar molecules linked by a glycosidic bond– Starch: storage form in plants

– Cellulose: most abundant CHO in nature

– Hemicellulose: principle component of plant cell wall

Polysaccharides

Function of CHO

• Source of energy

• Source of heat

• Building block for other nutrients

Sources of CHO

• Cereal Grains

– Most feedstuffs of plant origin are high in CHO content

CHO Digestion

• Dietary CHO must be converted to be absorbed– Simple sugars (monosaccharides)

• How?– Action of amylase enzyme

• Salivary amylase (swine, poultry)• Intestinal amylase

– Action of other disaccharidases • Produced by mucosal lining of duodenum

CHO Digestion

• Mammals do not produce enzymes necessary to digest oligosaccharides and celluloses (fibrous feedstuffs)– Digestion occurs as result of bacterial

fermentation• Where?

– Rumen– Large Intestine (cecum and colon)

CHO Digestion

• Fermentation yields:– CO2

– H2O

– Heat (heat increment)

– Volatile Fatty Acids (VFA) or also referred to as Short Chain Fatty Acids (SCFA)

VFA Production

• Serve as 70 - 80% of energy requirement in ruminants – VFA’s produced in rumen

• Serve as ~16% of Maintenance energy requirement in swine – VFA’s produced in large intestine

VFAs

• Acetate with higher roughage levels

– Produced by cellulolytic & hemicellulolytic bacteria

VFAs

• Propionate with higher concentrate levels

Feed efficiency

– Ionophores increase propionate production

VFAs

• Butyrate– Energy source for rumen wall growth

• Papillae growth

– Energy source for colonic cell growth• monogastrics

VFAs

• Lactate (not volatile)– Anaerobic conditions

rumen and blood pH

– Inhibits most microbial growth

– Acidosis situation

CHO Absorption

• Once simple sugars are formed, they are absorbed rapidly by small intestine

• Then monosaccharides diffuse into the portal vein which transports them to sites of metabolism

VFA Absorption

• Absorbed through the rumen wall or large intestine mucosa

• Provide energy source to the animal

LIPIDS

Lipids

• Insoluble in water but soluble in organic solvents

• Dense energy source:– 1 g fat = 9.45 kcal GE– 1 g protein = 4.5 kcal GE– 1 g CHO = 4.2 kcal GE

• Thus, fat produces 2.25 times the energy than CHO

Lipids

• Triglyceride: primary storage form of lipids

• Saturated fatty acids: contain no double bonds

• Unsaturated fatty acids: contain 1 or more double bonds

Lipids

Lipids

• Fats = solid at room temp = animal origin– saturated

• Oils = liquid at room temp = plant origin– unsaturated

Functions of Lipids

• Dietary energy supply

• Source of insulation & protection

• Source of essential fatty acids (EFA)

• Carrier for fat soluble vitamins

Lipids

• Essential fatty acids (EFA): Those fatty acids that an animal requires, but which it cannot synthesize in adequate amounts to meet the animal’s need– Linoleic C18:2– Linolenic C18:3– Arachidonic C20:4

EFA

• Physiological needs:– Cell membrane structure– Synthesis of prostaglandins which

control blood pressure and smooth muscle contractions

• Deficiency:– Scaly, flaky skin (Poor feather growth)– Poor growth

Sources of Lipids (EFA)

• Most feeds contain low levels– > 10%

• Unprocessed oil seeds (soybean, cottonseed, sunflower seed) contain up to 20% fat

• Traditionally, if additional fat is needed it is added to the diet– Animal fats– Vegetable oils

Lipid Digestion

• Occurs in the small intestine (duodenum)

• Bile produced by liver emulsifies fat

• Pancreatic lipase (enzyme) breaks apart fat for absorption

Lipid Absorption

• Monoglycerides (MG)—absorbed into SI mucosal cells

• Free Fatty Acids (FFA)—absorbed into SI mucosal cells or enter blood circulation directly

Lipid Absorption

• Very efficient– Absorption rates range from 70-96%

• Generally, oils (unsaturated fats) are absorbed more completely that fats (saturated fats)

Ketosis

• Disorder of metabolism– Insufficient energy intake in high producing

animals (e.g. Dairy cattle in early lactation and sheep in late pregnancy)

– Results in catabolism (breakdown) of body energy (fat) reserves

Ketosis

• 2 C fragments (ketones) of fat catabolism (breakdown) build up

• Toxic levels cause– Body weight loss– Abortion– Poor milk production

PROTEINS

Proteins

• Principal constituent of organs and soft tissues

• Highest concentration of any nutrient, except water, in the body of all living organisms and animals

• Required for life

Proteins

• DEFINITION: Protein are long chains of amino acids (AA)– Formed by peptide linkages

• Amino group + carbon skeleton

Proteins

Amino Acid (AA) Protein (2 AA joined by peptide bond between carboxyl and amino group

Proteins

• Dietary requirements highest in young, growing animals and declines at maturity

• Large molecules that vary greatly in in size, shape, and function– MW = 5000 to millions

Categories of Protein

1. Essential Amino Acids (EAA):

– required in the diet – cannot be synthesized at a rate sufficient to

meet the nutritional requirements

Essential AA

• PTV TIM HALL (KNOW!)

• Phenylalanine

•Threonine

•Valine

• Tryptophan

• Isoleucine

• Methionine

• Histidine

• Arginine

• Lysine

• Leucine

Categories of Protein

2. Nonessential AA– animal can produce enough to meet it’s

requirements

3. Semi-essential AA– Animal can not always produce enough to

meet its requirements

Functions of Protein

• Basic structural units– Collagen, blood, elastin

• Body metabolism– Enzymes, hormones, immune system,

hereditary transmission

• Production– Meat, milk, skin/hair

Protein Deficiency

• Reduced growth & feed efficiency

• Infertility

• Reduced birth weights

• Reduced milk production

Sources of Protein

• Most common feedstuffs contain some protein (the quality is another issue)

• KEY: to combine feedstuffs into the diet so that AA requirements are met– e.g. Using a corn-soybean meal diet for pigs

Protein Digestion

• Proteins must be broken down into AA for absorption in the GIT

– Exception! Early in life (> 48 h after birth) proteins from milk (immunoglobulins) can be absorbed intact across the intestinal epithelium

Protein Digestion/Absorption in Monogastrics

Monogastric Protein Digestion

• Stomach: HCl unfolds (denatures) proteins and activates pepsinogen secreted by stomach to pepsin– Pepsin begins protein digestion to peptides

(short-chain proteins)

• Small intestine: enzymes (trypsin) break peptides into AA

Monogastric Protein Absorption

• AA are absorbed in anterior part of the small intestine– Jejunum and ileum

• AA are absorbed and transported to tissue via blood

Protein Digestion and Absorption in Ruminants

Ruminant Protein Digestion

• In rumen, microbes break down protein to peptides and AA and then degraded further to ammonia, VFAs, and carbon dioxide

• Ammonia and/or NPN (urea) + CHO source form microbial proteins

Ruminant Protein Absorption

• Protein can be absorbed through rumen wall as ammonia

• Microbial proteins pass to the lower intestine where they are converted to AA and absorbed

Fates of Absorbed AA

1. Tissue protein synthesis

2. Synthesis of enzymes, hormones & other metabolites

3. Use for energy (inefficient energy source)

MINERALS

Minerals

• Inorganic components of the diet

• Can not be synthesized or decomposed by chemical reactions

• Total mineral content is called “ash”

• Makes up 3-5% of the body weight

Categories of Minerals

• Macro Minerals: Minerals normally present at greater levels in animal body or needed in large amounts in the diet (found in concentrations > 100 ppm)– Calcium (Ca)– Phosphorus (P)– Sodium (Na)– Chloride (Cl)– Magnesium (Mg)– Potassium (K)– Sulfur (S)

Categories of Minerals

• Micro (Trace) Minerals: Minerals normally present at low levels in animal body or needed in small amounts in the diet (found in concentrations < 100 ppm)– Cobalt (Co)– Copper (Cu)– Fluoride (Fl)– Iodine (I)– Iron (Fe)– Manganese (Mn)– Molybdenum (Mo)– Selenium (Se)– Zinc (Zn)

General Mineral Functions

• Skeletal formation and maintenance (Ca, P, Mg, Cu, Mn)

• Protein synthesis (P, S, Zn)

• Oxygen transport (Fe, Cu)

• Fluid balance—osmotic pressure (Na, Cl, K)

• Acid-base balance regulation (Na, Cl, K)

• Activators or components of enzyme systems (Ca, P, K, Mg, Fe, Cu, Mn, Zn)

• Mineral-Vitamin relationships (Ca, P, Co, Se)

Macro Mineral Deficiencies

• Ca and P– Inadequate bone mineralization

• Rickets (young)• Osteomalacia (adult)

– Phytate P—bound and unavailable to nonruminants

• Mg– Grass tetany-convulsions, coma, death

• Likely in grazing, lactating females in early spring or fall• Mg is there in the plant, just in bound form due to lack of sunlight

Macro Mineral Deficiencies

• Fe– Anemia (insufficient hemoglobin)– Young pigs (rapid growth, low stores, low Fe

in milk)

Trace Mineral Deficiencies

• Mn– Poor growth– Poultry—Perosis—deformed and enlarged

hock joints

• I– Goiter—swollen thyroid


• Cu– Fading hair coat color (depigmentation)– Low Cu utilization may result when excess Mo or Zn

• Zn– Parakeratosis (dermatitis-thickening of skin)– Poor hair or feather development– Exacerbated by high Ca


• Se– White muscle disease-nutritional muscular

dystrophy• Muscle appears white due to Ca-P deposits

– Due to low concentration of Se in soil

Mineral Toxicities

• Usually not a problem ($)• NaCl can be for swine and poultry

– Levels above 8%--causes nervous disorders

• Cu a big problem for sheep and young animals– Mineral mixes for other species/age groups used

• Se has a small margin between requirement (0.3 ppm) & toxicity (8 ppm)– Plants grown in regions of high soil Se

Sources of Minerals

• Forages usually considered good sources of minerals– Largely dependant on soil conditions

• Grains are fair source of P, but low in other minerals

• Mineral premixes

• Mineral blocks

Mineral Absorption

• Minerals are converted to their ionic form and absorbed in the small intestine

Vitamins

• Organic substances required by the animal in very small amounts

• Necessary for metabolic activity but not part of body structure

• Content varies greatly in the feed• Requirements depend on species

– Monogastrics = a lot b/c cannot synthesize– Ruminants = few vitamins due to microbial synthesis

Types of Vitamins

• Fat-soluble vitamins – Vit A (carotene): vision– Vit D: Ca, P absorption– Vit E (tocopherol): antioxidant– Vit K (menadione): blood clotting

• Short shelf life (3-4 months)• Need lipids for absorption• Destroyed by heat, minerals

Types of Vitamins

• Water-soluble vitamins– Thiamine– Riboflavin– Niacin– Pyridoxine– Pantothenic acid– Biotin– Choline– Folic acid– Vitamin B12

– Vitamin C

B Complex Vitamins

Vitamin Functions

• Reproduction

• Fetal Development

• Colostrum Production

• Milk production

• Wool

• Egg

• Racing

Vitamin Deficiencies

• Vitamin A– Xerophtalmia: night blindness– Poor growth, reproductive failure

• Vitamin D– Rickets– Osteomalacia

• Vitamin K– Poor blood clotting/hemorrhaging

Vitamin Deficiencies

• Vitamin C– Scurvy: slow wound healing, spongy gums,

swollen joints, anemia

• B Complex Vitamins– Reduced growth/poor appetite– Dermatitis– Muscular incoordination

Most likely deficient…

• In practical situations:– Ruminants: A, E, D (limited circumstances)

– Swine: riboflavin, niacin, pantothenic acid, choline, B12, A, D, and sometimes E

– Poultry: All vitamins except Vitamin C, inositol, and PABA

Vitamin Toxicity

• Unlikely ($)

• Generally nontoxic– Exceptions:

• A, D, Niacin, Pyridoxine, Choline

Sources of Vitamins

• A: green, leafy forages, corn, fish oil

• D: fish oils, sun-cured hay

• E: seed germ oils, green forage or hay

• K: green forage, fish meal, synthetic menadione

Sources of Vitamins

• B Vitamins: green forages usually– Niacin: present in grains, but unavailable to

nonruminants

• B12: protein feeds of animal origin, fermentation products

• C: citrus fruits, green, leafy forages, well-cured hay

Sources of Vitamins

• Most nonruminants rations contain a vitamin premix– Consume basically no forages and B vitamins

are poorly available from cereal grains

Vitamin Absorption

• Most vitamins are absorbed in the upper portion of the small intestine

• Water soluble vitamins are rapidly absorbed

• Fat soluble vitamin absorption relies on fat absorption mechanisms

Nutrition

• Nutrition– provide animals with nutrients to enable them to:

• maintain grow• reproduce lay eggs• lactate produce wool• work

– PROFIT – feed animals adequately & economically– first must understand process of digestion and

absorption of nutrients from feeds

Animal Classification By Type of Food Consumed

• Herbivore - Depends entirely on plant food

- Sheep, Cattle, Horses

• Carnivore – Almost entirely on meat for food- Dog

• Omnivore – Both meat and plants for food- Swine, Chickens, Humans

Animal Classification By Type Digestive System

• Major differences in anatomy and physiology of digestive tracts of different species

• Affects nature of digestive processes and the kind of feed that can be utilized by the animal

• Based upon type of digestive tract, 4 different classifications can be made.

Animal Classification By Type Digestive System

Monogastrics – Major Category• 1. Simple Stomach – Pigs, Humans, Dogs• 2. Avian – Chickens, Turkeys• 3. Pseudo Ruminants – Horses, Rabbits

Ruminants – Cattle, Sheep, Goats

Figure 6–3: Swine digestive tract.

Swine: - “Simple stomach”, Limited capacity-Chemical secretions and enzymes are

critical for digestion -limited microbial action, limited fiber

digestion

Digestive System Parts and Functions - Swine

• Mouth – Initial breakdown of food, mechanical, amylase in saliva, some lipase

• Stomach – Initial digestion of food, broken to smaller particles

-Hydrochloric acid – HCl, breaking of bonds

-Pepsin – proteins to polypeptides


•Small Intestine – Further breakdown and absorption of food

Pancreatic Enzymes

-Lipase - fats to fatty acids and glycerol

-Trypsin - polypeptides to peptides

-Chymotrypsin – peptides to amino acids

-Amylase – starch to disaccharides

-Sucrase, Maltase, etc. – disaccharides to monosaccharides

Reduced particles are absorbed into the bloodstream across wall of the small intestine. Diffusion = passive, Transport = active.


•Cecum/Large Intestine – limited plant fiber digestion

-microbes present produce the enzyme cellulase

-cellulase breaks down cellulose (one type of plant fiber)

-very inefficient system in monogastrics (except horses)

Figure 6–7: Digestive system of the avian.

Avian – monogastric, similar to others except:

-different anatomy since no teeth to chew food

-Limited capacity

-Chemical secretions and enzymes are critical for digestion

-Limited microbial action

-Limited fiber digestion

Digestive System Parts and Functions - Avian

• Beak – procure food

• Crop – feed directly here from esophagus

-feed stored and soaked with water

• Proventriculus – True “stomach” in Avian species, adds and mixes in:

-Hydrochloric acid – HCl, breaking of bonds

-Pepsin – proteins to polypeptides

Digestive System Parts and Functions - Avian

•Gizzard – Contains grit, food is crushed and ground to smaller particles by strong muscular contractions.

•Small Intestine – Same as swine

•Cecum/Large Intestine – Same as swine

Figure 6–4: Digestive system of the ruminant.

Ruminants: 4 compartment “stomach”-Designed for fiber digestion with a high capacity-microorganisms in rumen to digest fiber – symbiotic relationshipCapacities of different parts?

80%

8% 5%

9%

Digestive System Parts and Functions - Ruminants

Mouth – like swine, no enzymes

Stomach compartments 1. Reticulum (honeycomb)

- hardware disease?

2. Rumen (fermentation vat)

Digestive System Parts and Functions - RuminantsFunctions of the Rumen:

• Vat contains slurry of fluid, grain (bottom), boluses of forage and microorganisms

• Microorganisms are bacteria and protozoa, type changes with type of feed consumed (grain vs forages)

• In animals consuming forages, microbes present will break down the plant fiber and:

- Produce energy to be absorbed through the rumen as VFAs

- Synthesize more microbes (comprised mainly of protein) that are digested as a source of protein for the animal

- Synthesize ALL essential amino acids and B Vitamins


Functions of the Rumen - continued:

• Major VFAs are Acetate, Propionate and Butyrate

• Process of digestion of food by microbes is fermentation

• Rumination is regurgitation of forage boluses from rumen and reticulum

• Eructation is the belching of gases (CO2 and Methane) produced by the fermentation process – bloat

Figure 6–5: Side view (right side) of the rumen.

Is the rumen functional in newborn ruminants???



Stomach compartments - continued 3. Omasum (manyplies)

- adds water to or absorbs water from rumen contents

4. Abomasum (true stomach)-performs very similar functions as in

monogastric animals


•Small Intestine – Similar to swine

•Cecum/Large Intestine – Similar to swine

Pseudo Ruminants: Monogastric, single compartment stomach

• have a greatly enlarged cecum.

• have a large amount of “hind – gut” fermentation.

• digest fiber, can use forages as part of diet

Digestive System Parts and Functions - Horses

Functions of the Cecum

• microbes present break down the plant fiber:- Produce energy to be absorbed through the cecum as VFAs

– less efficient than rumen

- Synthesize more microbes, vitamins and amino acids, not digested

and used since cecum is downstream of digestive organs (stomach and small intestine) – Some are absorbed

- Require higher quality feed and forage

Nutrients

6 major classes1. Water

2. carbohydrates -

3. lipids -

4. proteins

5. vitamins

6. minerals

Energy

Figure 5–1: The essential nutrients.1Mnemonic device for remembering essential amino acids 5 MATT HILL VP.2For poultry, two additional amino acids are needed: glycine and proline.3Arachidonic acid can be synthesized from linoleic acid if it is available so it is only essential if linoleic acid is absent or in short supply.4Authors vary on whether or not to list sulfur as a macromineral or micromineral. The discrepancy arises because only a very small amount of inorganic S is needed but the sulfur-containing amino acids (organic S) are needed in larger quantities.

Nutrients

1. Water– Functions:

a. part of metabolic reactions

b. transports nutrients

c. temperature regulation

– moisture in feed?• % in grazed forages, silage, hay, corn?

Nutrients

2. Carbohydratesa. Types:

• simple = starches & sugars• complex = cellulose (plant cell walls = fiber)

b. Function:

source of energy• monogastrics – from grains or cecum (horses)

• ruminants – from volatile fatty acids

Nutrients

3. Lipids (fats & oils)– most feeds contain 1-5% fat or oil– composed of 3 fatty acids & glycerol– Functions:

a. energy source• 2.25 x more energy than carbohydrates

Nutrients

4. Proteins– 25 amino acids are building blocks of animals – 10 essential amino acids – not synthesized by body

tissues• Provided by microbial synthesis in ruminants• Must be in diet of all monogastrics• 1st limiting = LYSINE

– only nutrient containing nitrogen (16%)

Figure 5–1: 1Mnemonic device for remembering essential amino acids 5 MATT HILL VP.

Nutrients

Nutrients

Function of Proteins

• supply amino acids for body proteins

- muscle; bone; connective tissue; hormones; enzymes; antibodies; milk components; cell repair

small amounts for specific body functions

a. 2 classifications

1. water soluble – C & B-complex (see Fig 5-1)

– microbes synthesize in ruminants & horses

2. fat soluble – A, D, E, K

– A & E required in diets of all animals

– D – produced by effects of sun on skin

– K – synthesis by rumen/cecum microbes

Nutrients

5. Vitaminsb. Functions:

1. enzyme cofactors; blood clotting; bone health; health of internal linings of body

2. deficiencies lead to specific disorders

Example Disorders:

blood clotting

= K

scurvy

= C

6. Minerals– inorganic

(contain no carbon); are elements

NutrientsMineral Functions

-part of some amino acids & vitamins; metabolic reactions; enzyme function; body structure; transport oxygen

Deficiency examples:

White muscle

=selenium

Grass Tetany

=magnesium

Rickets

=calcium

White hair on black cattle

=copper

Anemia

=iron

Retained Placenta

=selenium and Vitamin E

• Slides after this point not used in 2002 lectures.

• STUDENTS – you are not responsible for the information beyond this point on the exam.

Figure 5–9: Schematic diagram for partitioning energy values of feeds. (Source: Adapted from Wagner, 1977. Used with permission.)

Nutrient Requirements for Maintenance, Growth, and Production

• Feed animals to meet nutrient requirements for:

1. maintenance – (about ½ of feed meets this)• no growth or production• met before supplying any other body function


2. growth– increase number and(or) size of cells– protein synthesis > protein breakdown– build muscle, bone, connective tissue


3. production– fattening/finishing– reproduction– lactation– egg laying– work– wool

Digestion in the Ruminant


Largest % of herbivores

I. Main fxn of complex stomach of ruminant

• Utilize the largest CHO source in the world as an energy source

• Produce food and other products

Anatomy

Mouth

Esophagus

Rumen

Reticulum

OmasumAbomasum

SmallIntestine

Cecum

LargeIntestine


A. Mouth 1. No upper teeth

2. Dental pad


A. Mouth 1. No upper teeth

2. Dental pad

3. Particle size reduction by teeth grinding against dental pad

4. Saliva

1. Moistens food

2. More importantly provides buffer for rumen

3. Rumen microorganisms produce Volatile Fatty ACIDS


B. Esophagus – A. Same general fxn as in monogastric

C. Complex stomach comprised of four compartments

1. Rumena. Contents = ~20% BW of animal

b. Volume – • 5 – 60 gallons liquid• 5 – 50 lb dry material


Stomach complex con’t2. Reticulum

3. Omassum

4. Abomasuma. True glandular stomach

b. Lined with mucous membrane and gastric juice secreted


D. Rumen/reticulum and omassum collectively term:

Forestomachs

– Lining of these tissues:• Stratified squamous epithelium

– “layered, scaly” epithelium

• Not glandular– No secretions


E. Esophageal groove (reticular groove)

1. Groove which can contract and form tube to bypass rumen/reticulum

2. Empties into omasum

3. Fxn =

a. Allow milk to pass directly to omasum and abomasum

b. Keep milk out of young ruminant’s undeveloped rumen


III. Rumen - Anatomy/Function

A. Main fxn = act as site of anaerobic bacterial fermentation

1. Anaerobic microorganisms live and reproduce

2. No oxygen = anaerobic

B. Undeveloped at birth – sterile

C. Partially developed at 4-6 weeks of age

D. 1st place food goes in adult

E. Some nutrients bypass anaerobic fermentation


F. Rumen wall covered with papillae1. Small finger-like projections.

2. Increase surface area.

3. Influence by diet and season.

G. Storage of food1. Consume large amounts can digest later.

– Regurgitation, remastication, etc.


IV. Microorganisms in the rumen digest

a. CHO – cellulose and starch

Fermentations produces Volatile Fatty Acids

Fiber (cellulose)Corn (starch) VFA’s

MO’s


b. VFA’sa. Acetate/acetic acid (2 carbons)

b. Propionate/propionic acid (3 carbons)

c. Butyrate/butyric acid (4 carbons)

c. VFA’s absorbed through rumen wallCan supply 50-100% of required energy for ruminant

CH

H

H

COH

O

CH

H

H

C

O

C

H

H OHCH

H

H

C

O

C

H

H

C

H

H OH


d. Main benefit of microbial fermentation• Produce microbial protein as they live and

reproduce

• Utilize urea (non-protein source)• Utilize plant/animal protein

Urea

Protein

AA

NH3 MCO protein

C skeleton VFA’s


e. Bacteria pass through rumen with feed to lower G.I. Tract– Protein (feed and microbial)

f. Microbial protein contains ~50% CP• Excellent protein source

g. Microorganism also synthesize:1. B vitamins – thus no req’t2. Vitamin K

h. Microorganism also contain:1. 1 – 2 % CHO2. 3% fat – essential FA’s present – no req’t for FA


V. Rumen provides favorable environment for microbial growth due to:

a. Buffered pH

b. Temperature maintained at 101 to 103 degrees

c. Primarily a liquid media

d. Food supply replenished daily

e. End products of digestion removed

f. Anaerobic

Digestion in the Ruminant - 2

I. Anatomy – continued

A. Reticulum – Honey Comb1. Fxn – Site of microbial action & absorption of VFA’s

2. Fxn – Pacemaker for rumen contractions

a. Contractions start in reticulum spread to rumen

b. Mixes rumen contents


I. Anatomy – continued

A. Reticulum – Honey Combc. Heavy particles move to bottom, lighter ones float

d. Lighter particles subject to rumination

Rumination = regurgitation, remastication, resalivation, reglutition


• Omasum – “many piles”, lamina propia– Fxn is unclear– Some water and VFA absorption– Some mechanical digestion from lamina– Regulates particle size flowing to abomasum/S.I.

• Abomasum– True stomach– Secretions

• HCI – denatures protein, but also kills MCO• Mucin, pepsin, etc


d. Small intestine, large intestine– Very similar to that for non-ruminant

e. Post Gastric Fermentation1. Approximately 5-15% of cellulytic digestion can

occur in colon and cecum

2. MCO here as well but lost in feces, lose MCO protein

3. VA’s produced and can be absorbed through L.I.

4. Primary function is still water absorption

Rumination Process

Rumination Process

Define = set of steps that reduce particle size of digesta for passage to lower tract

1. Regurgitation a. Bolus is moved by reverse contraction of esophagus

from rumen to mouth

2. Remasticationa. Reduce particle size

3. Resalivationa. Buffer b. Nitrogen recycling

4. Reglutition

8 hrper day

Eructation

1. Process of removing gas from the rumen

a. 50 – 200 liters/day

b. Gases produced :

H2 – hydrogen

CO2 – carbon dioxide

CH4 – methane

H2S – hydrogen sulfide

Eructation

c. Rumen contraction forces gas to the back and then forward

d. Gas forced up esophagus to the trachea

GAS GAS

GAS

Eructation

2. Problem = Bloata. Primarily caused by inability to eructate

a. Froth

b. Foam

b. Secondarily caused by something anatomically wrong

c. Commonly seen distention of left side

Bloat

Eructation

2. Problem = Bloata. Primarily caused by inability to eructate

a. Froth

b. Foam

b. Secondarily caused by something anatomically wrong

c. Commonly seen distention of left side

d. Legumes (soluble protein) – primary cause

e. “Barn door left open” – wheat pasture, lush grass

f. Treatment/preventiona. Trochar

b. Ionphores

Documents

Animal Nutrition Mc Donald, Greehalgh and Warner. 1987. Animal Nutrition. Longman