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

● Source of energy for heat production, work and/or fat deposition

● Regulates body processes or activities and as constituents of body-produced regulators

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, either fresh or dry, but usually cereals.

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

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

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

source and stores of energy

in Animals, lipids are a major form of energy storage mainly as fat

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, and are easily destroyed through oxidation

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.

• many become toxic when given in excess

• classified as major or trace minerals

Fat Soluble Vitamins

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

Water Soluble Vitamins

Vitamins that are excreted in urine and poorly stored, requiring regular dietary supply. (A-B11 and vitamin C/ ascorbic acid)

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 - Lantana

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

Chromolaena odorata - Hagonoy/ Agonoy

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 (Centro Grass)

Improves protein content when intercropped with grass; leaves used as cheap protein source for broilers.

Pennisetum purpureum — Napier grass

● Highly productive in tropics

● Cut-and-carry, silage/hay

● CP: ~9.2%

Imperata cylindrica - cogon grass

• Low nutritive value

• Invasive weed; invades crop farms

Arachis pintoi (Pinto Peanut)

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

Themeda triandra (Bagokbok)

Moderate nutritive value (CP: 2.8-12.4%); young stage palatable, Drought-resistant, restores grassland soilses.

Morus sp. (Mullberry)

• High-protein forage for poultry & cattle; highly digestible

• Leaves & stalks fed to ruminants

• Contains high water-soluble carbohydrates and starch

• CP: approx. 12–22% (very high

Setaria sphacelata (Setaria grass)

● Permanent pasture

● Soft foliage, no bristles (easy handling)

● Good for hay, ensiles well

Paspalum atratum (Paspalum)

● Easy to sow, quick to establish

● Tolerates temporary flooding

● Good for cut-and-carry; palatable when young

Trichanthera gigantea (Madre de agua)

● Protein-rich leaves and seeds

● High fiber leaves

● Used as supplemental protein feed

Cajanus cajan (Pigeon pea)

● High-protein forage source

● Edible seeds and leaves for animals

Brachiaria ruziziensis (Ruzi grass)

● Good nutritive value, palatable

● Ideal for grazing under coconuts

● Can be cut for hay or fed fresh

Brachiaria mutica (Para grass)

● Used in tropics for beef pasture

● Highly palatable, nutritious

● CP: ~10.2%

● CF: ~23.6%

Brachiaria humidicola  (Koronovia grass/ Humidicola)

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

Brachiaria decumbens (Signal grass)

● Permanent pasture

● Palatable, withstands heavy grazing

Urochloa brizantha (Brizantha/ Palisade grass)

● Multi-purpose pasture; high persistence

● Works for grazing, silage, hay

● Also for erosion control & hedges

Andropogon gayanus (Gamba grass)

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

Stylosanthes guianensis (Stylo grass)

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

Paspalum conjugatum (Carabao grass)

For livestock grazing; also used in landscaping.

Synedrella nodiflora (Synedrella)

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

known as “manyplies/ butcher’s bible. 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

● Up to 150 ft long

● ~20-gallon capacity

● Receives enzymes from pancreas & bile from gall bladder

● pH rises from ~2.5 to 7–8

● Primary site of active nutrient absorption

● Villi increase absorption surface area

● Rumen-bypass proteins absorbed here

Cellulolytic bacteria

e.g., Bacteroides succinogenes, Ruminococcus spp.

Hemicellulose fermenters

Butyvibrio fibriaduens, Bacteriades ruminococcus spp.

Cecum

● ~3 ft long

● ~2 gallons (minimal role in cattle)

Amylolytic bacteria

• digestive starch

• sugar fermenters

Colon

Final step before the release of feces, 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
(Beak → Mouth → Esophagus → Crop → Proventriculus → Gizzard → Small Intestine → Ceca → Large Intestine → Cloaca → Vent)

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 (temporary storage)

Proventriculus (Glandular Stomach)

Secretes digestive enzymes and acids, Chemical digestion begins

Sorghum (Sorghum bicolor)

Contains toxics substance called Cyanogenic glycosides

Cassava meal (Maninot Esculenta)

Contains toxics substance called Cyanogenic glycosides

Soybean Meal (Glycine max)

Contains toxics substance called Trypsin, inhibitors, Lectins, saponins