Chapter 1-3 Concepts of Nutrition

The food components capable of being utilized by animals are described as nutrients. That supports normal reproduction, growth, lactation or maintenance.

The six classes of nutrient: water, protein ( amino acids ), carbohydrate, lipids, vitamins and inorganic elements. Nutrient support cellular need for water, fuel, structural constituents, metabolic regulation.

Food: an edible material that provides nutrients. Feed: a food but is more applied to animal food than to human food.

Foodstuff (Feedstuff ): any material made into food or feed. Diet: is a mixture of feedstuff used to supply nutrient to an animal. Ration: is a daily supply of feed.

1.1 Water 75-80% in newborn animals, 50% in mature fat animals

Table 1.1 Composition of some plant and animal products expressed on a fresh basis and a dry matter basis

1.1 Water The water content of food is variable 60g/Kg in concentrate to 900 g/Kg in some root crops. Because of this great variation in water content, the composition of foods is often expressed on a dry matter basis.(table 1.1).

1.2 Dry matter (DM) and its components Organic material Different carbohydrate in animal and plant cell wall Cell wall of plant consist of carbohydrate material (cellulose), the wall of animal cells are lipid and protein.

1.2 Dry matter (DM) and its components The lipid content Protein component Organic acid occur in animal and plant Inorganic material Vitamin Other inorganic: calcium and phosphorus are major components of animal.

Chapter 3 Common Methods of Analysis for Nutrients and Feedstuff Sampling for analysis small amount of material that give the best reasonable estimate of the total batch. Ex.: protein determination, 2g beef carcass, rib cut give a accurate estimate of the total carcass for fat, protein water and ash.

Analytical methods 1.chemical method: use various chemical procedures that are specific for a given element or compound. It can’t answer the availability of nutrients from feeds 2.biological method: tell the amount of a nutrient that animal uses from feeds. Chick and rat often use this. 3.microbiological method: determine how much of a given amino acid or vitamin is available in a given product or mixture.It may not be applicable to animals.

Proximate analysis is developed in Germany well over a century ago. It has many faults. Forage analysis by the detergent extration methods of Van Soest(1982).

Proximate analysis of foods (Composition of food) Moisture Ash Crude protein (CP) Ether extract (EE) Carbohydrate Crude fibre (CF) Nitrogen-free extractives (NFE)

Moisture The loss in weight that result from drying a known weight of food to constant weight at 100 ℃.

Ash The loss in weight of the food at 550 ℃ until all carbon has been removed. The residue is the ash and is taken to represent the inorganic constituents of the food.

Crude protein (CP) Calculated from the nitrogen content of the food(16%), determined by a modification of a technique originally devised by Kjeldahl method. Nitrogen x 6.25=protein

Ether extract (EE) Determined by subjecting the food to a continuous extraction with petroleum ether for a defined period. The residue, after evaporation of the solvent, is the ether extract.

Crude fibre (CF) Determined by subjecting the residue food from ether extraction to successive treatments with boiling acid and alkali of defined concentration; the organic residue is the crude fiber.

Nitrogen-free extractives (NFE) When the sum of the amounts of moisture, ash, crude protein, ether extract and crude fibre, the difference is designated the nitrogen-free extractives. NFE is made up primarily of readily available carbohydrates, such as the sugers and starches, it may also contain some hemicellulose and lignin in the forage.

Measurement of protein in foods for ruminants Fig 1.1 Proposed model for characterization of foods for ruminants. Cornell net carbohydrate and protein system, The neutral and acid detergent extraction of Van Soest.

Table 1.2 Classification of forage fractions using the detergent methods of Van Soest.

Fibre NDF (neutral detergent fiber) The residure after extraction with boiling neutral detergent, consist mainly of lignin, cellulose and hemicellulose. ADF(acid detergent fiber) The residure after extraction with boiling acid detergent, consist mainly of lignin, cellulose.

Dietary fibre Defined as lignin plus those polysaccharides that cannot be digested by monogastric endogenous enzymes.

NSC (Non-structural carbohydrate ) The fraction obtained by subtracting the sum of the amounts (g/kg) of CP, EE, ash and NDF from 1000

NSP(non starch polysaccharide) Represent the components of cell walls.

Modern analytical methods Starch and sugars Minerals: Atomic Absorption Spectrophotometry Amino acid Fatty acid: Gas-liquid chromatography Energy : bomb calorimetry