Agri 21 - Lab Theoretical

Physical Evaluation

– Sensory examination of feed ingredients

• Color

• Odor

• Texture

• Dampness

• Presence of adulterant/foreign material

• Presence of mold and insect infestation

Feed Microscopy

– Study of the appearance of feed sample under the

microscope

– Determines the purity of the feed sample or detects

presence/ absence of adulterants

Adulterants

– Substances/ impurities of cheaper value and low

quality that are intentionally added to the feeds to

change its physical and chemical characteristics

– Adds to the bulk or weight of the feed

Proximate Analysis (Wendee Method)

is the most

extensively used method for the determination of the nutritive

value of feeds. The analyses include moisture, ether extract,

crude fiber, crude protein, ash and nitrogen free extract.

Moisture - Oven

- Drying a sample and

determining moisture

content by the

weight difference

between dry and wet

material

Crude Fat - Soxhlet apparatus

- Fats are dissolved

with organic solvent

(petroleum ether)

Crude Fiber - Refluxing unit

- Digestion with weak acid

(H2SO4) followed by the digestion with weak alkali (NaOH)

- Insoluble carbohydrate

fraction (cellulose, hemicellulose and lignin)

Crude protein - Kjeldahl apparatus

is computed as total nitrogen content of the

sample multiplied by 6.25.

Ash - Muffle Furnace

- Total inorganic matter

(mineral) content in a

feed

Nitrogen-free extract (NFE)

- Soluble fraction of carbohydrates such as

starch
NFE = 100 – (moisture + ash + crude protein + crude fat + crude fiber)

22.35%

If a feed sample has 85% dry matter content (or

15% moisture) and 19% crude protein, the crude protein

content on a dry matter basis would be:

Microbial Evaluation

Determine the presence of Salmonella spp. and

mycotoxin-producing fungi such as Aspergillus flavus

and Fusarium in feeds.

Safe

Characteristics of a good ration

– free from anti-nutritional factors (ANF) and toxic

substances

Acceptable and palatable to the animal

Characteristics of a good ration

– stimulate feed intake and will not cause digestive

disturbances

Economical

Characteristics of a good ration

– affordable and efficient; least-cost ration

Nutritionally Balance

Characteristics of a good ration

– digestibility and availability of nutrients

Know the species and class
Determine the nutrient requirements
Determine what feed ingredients are available.
Know the nutrient composition and unit price
Consider the limitation of usage
Determine a suitable combination
Check ration for each nutrient content.

Steps in Feed Formulation

Pearson Square Method

• Determine correct proportions of two feed ingredients or

two feed ingredient groups (energy or protein feeds)

Ether extract

is the sum of all the ether-soluble materials. It

is determined by extracting a finely ground dried sample with

boiling ether and then distilling off the ether and weighing

the residue.

Moisture

is determined by accurately weighing a finely

ground sample before and after drying it to constant weight

at 105 °C (usually overnight).

Feeds

defined as any material grown or developed to be fed to livestock

and poultry to sustain or support life.

Roughages

feed materials containing more than 18% crude fiber

and are generally low in energy content

Concentrates

feeds that are high in energy content (>60% TDN)

and low in crude fiber (<18%)

Supplements

feedstuffs that are mixed with a primary grain and/or

roughage to provide all the nutrients required to support the form of

production for which it is intended

Feed additives

non-nutritive substances added in the feed for

specific purposes such as enzymes, probiotics, prebiotics,

acidifiers, etc.

Grasses

normally with 6-10% crude protein and <0.9% calcium content

Legumes and other forages

normally with 10.5% crude protein or

higher and >0.9% calcium content

Guinea grass

Distinctive parts: presence of trichomes in nodes

Para grass

Distinctive parts: presence of trichomes in whole culm

Napier grass

Distinctive parts: rough leaves (no trichomes in culm)

Star grass

Distinctive parts: presence of roots at nodes

Alabang X

Distinctive parts: presence of trichomes at nodes

Energy feeds

contain a variable amount of nutrients but

exceptionally high in energy.

Protein feeds

derived from end-products of meat

packaging, dairy processing, and marine industries

Plant protein feeds

derived from end-products of oil extraction

from a group of seeds

Synthetic amino acids

These are feedstuff carrying large amounts

of one or more pure amino acids, which may be added to a ration to

make up for an amino acid deficiency.

Mineral supplements

These are feedstuffs rich in one or more of

the inorganic elements needed to perform certain essential body

functions.

Vitamin supplements

Vitamin premix is a mixture of different

vitamins and a carrier formulated to provide the requirements of the

animals when added in the diet at a recommended rate.

Enzymes

are protein molecules that can catalyze biochemical

reactions.

Antioxidants

are substances that protect the polyunsaturated fatty

acids from destruction by peroxidation.

Total Digestible Nutrients (TDN)

- indicates the relative energy value

of a feed; the sum of the digestible protein, digestible fiber,

digestible fat, and digestible nitrogen-free extract

Soilage

fresh herbage cut and chopped in the field and fed to

animals in confinement.

Silage

fermented forage stored under anaerobic conditions in a

silo. Forages made into silage are green chops or dry crops to which

the moisture must be maintained at 60-65%.

Hay

forage/roughage harvested during the growing period and

preserved by drying for later use in animal feeding.

Crop residue

plant parts left in the field after harvesting the

primary crop such as corn stover and rice straw.