Biochemical Analysis in Animal Nutrition

6.25 factor in Kjeldahl method

Because leaf and stem tissue proteins contain ~16% nitrogen, or a 1:6.25 ratio of nitrogen to protein.

Nitrogenous compounds in crude protein estimation

Urea and ammonia; nitrate is not included.

Limitation of crude fat analysis

It also extracts other lipophilic compounds like waxes, steroids, pigments, alcohols, and esters.

Soxhlet apparatus significance

It performs ether extraction to estimate total crude fat.

Crude fiber representation

Because it only partially measures cellulose and lignin, missing other indigestible fiber components.

Nitrogen-free extract (NFE) calculation

NFE represents primarily starches and sugars, but it is calculated by difference, accumulating all errors from other proximate components.

Physiological roles of water

1. Biochemical reactions, 2. Thermoregulation via heat dissipation, 3. Structural support in body fluids like synovial fluid.

Energy yield of fats vs carbohydrates

Fats have more C-H bonds and less oxygen, allowing higher oxidation and 2.25× more energy than CHO/protein.

High iodine number in fat quality

A high degree of unsaturation due to more double bonds in the fat molecules.

Importance of saponification value

It indicates molecular weight and average chain length by measuring how much alkali is needed to hydrolyze fat.

Vitamin deficiency and retained placenta

Vitamin A (Retinol).

Vitamin D2 vs D3 sources

D2 comes from plants (ergocalciferol), D3 from animals (cholecalciferol), both require UV activation.

Vitamin E deficiency condition

Muscular dystrophy; Se works with Vit E as antioxidant co-factors.

Vitamin K deficiency effect

Because it impairs prothrombin formation, which is essential for blood clotting.

Thiamine (B1) deficiency pathway

Carbohydrate metabolism; sign is general weakness and anorexia.

Riboflavin (B2) role

As a coenzyme for flavoproteins involved in redox reactions of metabolism.

Tryptophan and niacin synthesis

Tryptophan; some animals like cats have low conversion rates.

Pantothenic acid deficiency gait

"Goose-stepping"; part of CoA in acetylation reactions.

Avidin effect on biotin

Avidin binds biotin tightly, leading to biotin deficiency.

Folic acid (B9) role in poultry

Poor egg production and hatchability.

Choline functions

As a methyl donor in lipid metabolism; acetylcholine acts in nerve synapses.

Cobalt's role in vitamin B12 synthesis

Cobalt; deficiency causes anemia and unthriftiness.

Most abundant mineral in the body

Calcium; it regulates muscle contraction, nerve impulse transmission, and blood coagulation.

Phosphorus role in metabolism

Major bone constituent and part of ATP/enzymatic systems in energy metabolism.

Grass tetany cause

Early spring grass low in magnesium; results in Mg deficiency (hypomagnesemia).

Sulfur deficiency in ruminants

Because sulfur is required for microbial synthesis of sulfur-containing amino acids like cysteine.

Iodine's role in thyroid hormone synthesis

Iodine; deficiency causes goiter and reproductive issues.

Zinc's role in enzyme systems

Zn is a cofactor in digestive/metabolic enzymes; deficiency causes parakeratosis.

Selenium's protective role

By acting as glutathione peroxidase, converting hydrogen peroxide and lipid hydroperoxides to non-toxic forms.