Principles of Animal Nutrition: Key Concepts and Feed Types

Roughage

any feed high over about 20% in crude fiber and low under about 60% in TDN, on an air-dry basis.

Feed

edible material needed by animals

Basic Functions of Feed Nutrients

Builds and maintains body structure for growth, health and reproduction.

Ration

feed given to animals for one day

Ruminants

animals possessing compound stomach

Non-ruminants

animals with simple stomach

Nutrients

substances needed by animals to sustain life

Concentrates

feed with high protein content and low fiber

Water

The most basic nutrient because of its active and structural participation in life.

Fodder crops

feed material for ruminant animals

Silage

fermented forage crops

Soilage

fresh forage crops

Nutrient

any feed constituent which may function in the nutritive support of the animal.

Concentrate

any feed low below 20% in crude fiber and high over about 60% TDN on an air-dry basis.

Carbohydrates

Neutral chemical compounds with Carbon, Hydrogen and Oxygen

carbohydrates

Main component of all plants and many seeds.

Types of Carbohydrates

Fats and Oils, Monosaccharides, Disaccharides, Polysaccharides

Glucose

"grape sugar", the primary form utilized for energy production.

Fructose

"fruit sugar", sweetest among the naturally occurring carbohydrates

Galactose

component of milk sugar

Sucrose

"cane or beet sugar", commonly used as food sweetener

Maltose

"malt sugar", used in the manufacture of beer or scotch whiskey

Lactose

"milk sugar", imparts a faint sweet taste in milk

Starch

reserve carbohydrate in plants, primary energy source of animals

Glycogen

"animal starch", essential in energy

Metabolism

The sum of all chemical reactions that occur within a living organism.

Cellulose

Most abundant single polymer in the plant kingdom.

Lipids

Organic compounds that serve as electron carriers, substrates to enzymatic reactions, and components of biological membranes.

Essential Amino Acids

Amino acids that animals cannot make on their own and must obtain from food.

Macro Elements

Elements generally required at a relatively larger amount than trace elements, functioning as components of tissue structure.

Vitamins

Organic compounds needed in small amounts for normal growth and maintenance, which cannot be synthesized by animals.

Limiting Amino Acids

Amino acids that when deficient cause insufficient utilization of other amino acids in the diet.

Minerals

Essential nutrients that have metabolic roles, with deficiency causing symptoms.

Fat Soluble Vitamins

Vitamins that are stored in body fat and poorly excreted, causing deficiency to develop slowly.

Water Soluble Vitamins

Vitamins that are excreted in urine and poorly stored, requiring regular dietary supply.

Forages

Plant material (leaves and stems) eaten by grazing animals.

Types of Vitamins

Includes Fat Soluble Vitamins and Water Soluble Vitamins.

Types of Minerals

Includes Trace Elements and Macro Elements.

Trace Elements

Minerals present in the body in a concentration not greater than 50 mg/kg.

Examples of Essential Amino Acids

Phenylalanine, Methionine, Histidine, Arginine, Isoleucine, Threonine, Lysine, Tryptophan, Leucine, Valine.

Examples of Macro Elements

Calcium, phosphorus, potassium, sodium, chlorine, sulfur, and magnesium.

Examples of Vitamins

Includes Vitamins A (retinol), D, E, K, B1 (thiamin), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), biotin, folacin, B12 (cyanocobalamin), choline, and Vitamin C (ascorbic acid).

Vitamin C

The least stable vitamin, easily destroyed by heat and light.

Chicks

Need glycine in addition to the 10 essential amino acids.

Pigs

Do not need dietary arginine because they can synthesize it.

Grasses

Main feed for ruminants; higher biomass production than legumes; high yield and quick regrowth (growing point near ground).

Legumes

Higher quality feed than grasses; rich in protein, vitamins, minerals; improves animal performance; cheap source of feed.

Multi-Purpose Tree Species (MPTS)

High protein content; deep roots — good for dry seasons; examples: Ipil-ipil, Kakawate.

Lantana camara

Escaped ornamental plant; contains pentacyclic triterpenoid toxins; toxic to livestock, dogs, cats; causes liver failure, photosensitization (1-2 days after ingestion).

Chromolaena odorata

Causes liver toxicity, diarrhea, loss of appetite; can lead to death due to tissue anoxia (lack of oxygen in tissues).

Leucaena leucocephala (Ipil-Ipil)

High protein cattle fodder; contains mimosine (toxic amino acid)

Centrosema pubescens

Improves protein content when intercropped with grass; used for grazing, cut-and-carry, silage; leaves used as cheap protein source for broilers.

Pennisetum purpureum — Napier grass

Cut-and-carry forage for cattle, sheep, goats; highly productive in tropics; CP: ~9.2%.

Imperata cylindrica - cogon grass

Low nutritive value

Invasive weed; invades crop farms

Arachis pintoi

Used for hay, silage, pasture; Highly palatable, highly digestible Best mixed with grasses

Themeda triandra

Moderate nutritive value (CP: 2.8-12.4%); highly palatable, highly digestible; best mixed with grasses.

Morus sp.

High-protein forage for poultry & cattle; young stage palatable; drought-resistant, restores grassland soils.

Setaria sphacelata

Highly digestible; leaves & stalks fed to ruminants; contains high water-soluble carbohydrates and starch.

Paspalum atratum

Good for hay, ensiles well.

Trichanthera gigantea

Easy to sow, quick to establish; tolerates temporary flooding; good for cut-and-carry; palatable.

Cajanus cajan

Protein-rich leaves and seeds; high fiber leaves; used as supplemental protein feed when young.

Brachiaria ruziziensis

High-protein forage source; edible seeds and leaves for animals.

Brachiaria mutica

Good nutritive value, palatable; ideal for grazing under coconuts; can be cut for hay or fed fresh.

Brachiaria humidicola

Best in tropical lowlands; less growth in cool season, more in hot season.

Brachiaria decumbens

Used in tropics for beef pasture; highly palatable, nutritious; CP: ~10.2%; CF: ~23.6%.

Urochloa brizantha

Multi-purpose pasture; high persistence; palatable, withstands heavy grazing.

Andropogon gayanus

Used for grazing, hay, silage; heavy stocking capacity in wet season (4-5 heads/ha).

Stylosanthes guianensis

Cut-and-carry and grazing; palatable when mature; grows in poor soils; CP: ~12-20%.

Paspalum conjugatum

For livestock grazing; also used in landscaping.

Synedrella nodiflora

Consumed by cattle, horses, pigs; single stomach (e.g., pigs, dogs, horses, rabbits, poultry).

Monogastrics

Single stomach (e.g., pigs, dogs, horses, rabbits, poultry).

Ruminant Digestive System

Efficient use of high-roughage feed; common in humid, shaded soils.

Major organs of Ruminant Digestive System

Mouth, tongue, salivary glands, esophagus, four-compartment stomach (rumen, reticulum, omasum, abomasum).

Rumen

Fermentation vat; lined with papillae for absorption; ferments fiber, starch, sugars.

Omasum

Absorbs water & nutrients; highly developed in cattle.

Abomasum

True stomach; similar to monogastric stomach; secretes HCl and pepsin.

Digestibility

Measure of how well an animal's digestive system breaks down feed into absorbable nutrients.

Digestibility Coefficient

Percentage of a nutrient digested and absorbed from the feed.

Small Intestine

Primary site of active nutrient absorption; up to 150 ft long; ~20-gallon capacity.

Types of Rumen Microbes

Cellulolytic bacteria, e.g., Bacteroides succinogenes, Ruminococcus spp.

Hemicellulose fermenters

Butyvibrio fibriaduens, Bacteriades

Cecum

Water absorption primary function

ruminicola

Amylolytic bacteria

Colon

Digest starch, Sugar fermenters, major water absorption

Rectum

feces excretion

Gizzard (Ventriculus)

Muscular grinding organ, Mechanical digestion of feed (uses grit if available)

Ceca (Two Ceca)

Fermentation of undigested fiber, Produces cecal droppings (brown, pasty)

Large Intestine

Water absorption and formation of fecal matter

Cloaca

Common chamber where digestive, urinary, and reproductive systems meet

Monogastric Digestive System

One-compartment stomach, Species: swine, dogs, horses, rabbits, poultry (modifications exist)

Vent

Final exit point for feces and uric acid

Accessory Organs

Pancreas, liver, gall bladder assist digestion, Horse has no gall bladder

Beak

Feed intake and initial breakdown (no teeth, so minimal mechanical digestion)

Mouth

Saliva moistens feed, Enzymes begin digestion

Esophagus (Gullet)

Tube transporting swallowed feed to the crop

Crop

Storage pouch, Soften feed and allow limited fermentation

Proventriculus (Glandular Stomach)

Secretes digestive enzymes and acids, Chemical digestion begins

Brown Sugar

Energy Source, Color: Brown, Odor: Sweet, CP %: 80.00%

Blood Meal

Protein Source, Color: Reddish Black / Dark Brown

Rice Bran, D2

Energy Source, Color: Light Brown, Odor: Woody, CP %: 10.00%