Nutrient Classes in Nature:

1. Protein = amino acids linked together by peptide bonds (16% N)

2. Carbohydrates = simple = glucose; starch, fiber

3. Lipids = fats, glycerol backbone & 3 fatty acids – most concentrated form of energy (4, 4, 9 kcal/g for protein, carbohydrates, and fats, respectively)

4. Vitamins = fat soluble – A, D, E, K; H20 soluble – B complex & C

5. Minerals = Macro and Micro

6. Water = often forgot – cheapest to supply

7. Oxygen = not really a dietary nutrient

 

Proximate Analysis – used to evaluate nutritive content of feeds. Developed in 1860’s at the Weende Experiment Station, Germany.

1. Moisture = 100 oC

2. Ash = Muffle furance – burn – 400-600 oC

3. Kjeldahl N = protein (6.25 X %N) – Boil in H2SO4 – distill ammonia

4. Ether Extract = Fat, boil in ether, distill fat left

5. Crude Fiber = acid/base hydrolysis – boil in weak acid then weak base ® ~undigestible

6. N Free Extract = Calculated by difference, more readily available CHO’s

Plant Composition

Highly dependent upon function of the various parts.

Stem: = structural Þ contains cellulose and lignin – high CHO content

Leaves: = photosynthesis Þ requires enzymes – enzymes are proteins Þ leaves high in protein

Seeds: Germination and reproduction Þ storage site of nutrients

High in protein and energy

Surrounding the seed is a tough cellulose fiber

® grain sorghum (milo), corn, oats = crack, pop, roll, crimp, grind, etc. to increase digestibility

1. Cereal Grains: store energy as CHO (starch), corn wheat, barley

2. Oil-bearing Seeds: store energy as lipid (oil), soybean, cottonseed, penut

 

Animal Body Composition

 Water: Essential component of every cell

Blood = 90%

Bone = 45%

Muscle = 75%

Enamel = 5%

Fat: All cell membranes are composed of phospholipids

Adipose tissue = energy storage site in the body

Protein: Present in every cell of the body (membrane, enzyme,…)

Epithelial lining of the GI tract, respiratory system, urogenital, skin, hair, muscles, tendons (connective tissue)

Minerals:

Bones & teeth =

Ca, P, Mg

Tissues =

S & P (ATP)

Body Fluids =

Na, K, Cl (electrolytes)

Blood =

Fe (hemoglobin)

Carbohydrates: <1% in animals

Blood ~ free glucose

Muscle and liver = glycogen (animal starch)

Comparative Digestive Physiology

Meat Cut

Species

Composition

Diet

Digestion

Pork Chop

Pig

80% Protein

20% Ash

Corn

(Starch)

Hydrolytic

Ribeye Steak

Steer

80% Protein

20% Ash

Grass

(Cellulose)

Fermentive &

Hydrolytic

Steer can eat grass and produce meat products but pig can not ® because of digestion! Type of feed is determined by type of digestion.

Gastrointestinal, GI, Digestive, Alimentary, Gut = all the same thing

Two Types of Digestion

1. Hydrolytic: All digestive enzymes secreted by animal tissue

Occurs? = stomach, intestine, pancreas (secretes enzymes)

Species? = All are dependant on this type of digestion

2. Fermentive: Enzymes are of microbial origin (primarily bacteria & protozoa)

Occurs? Rumen, Cecum – these two "organs" contain a viable microbial population. **Microbes secrete the enzymes NOT the organs.

Species? Herbivores – Cows, sheep, horses, etc.