Animal Nutrition and Food Components Flashcards

A comprehensive set of practice questions covering animal nutrition basics, chemical analysis of feed, carbohydrate and lipid structures, and protein classifications based on lecture transcripts.

What are the six fractions separated during proximate analysis of food?

Moisture, ash, crude protein, ether extract, crude fibre, and nitrogen-free extractives.

Why is feed efficiency important regarding environmental impact?

It reduces land use and decreases manure composition of nutrients like phosphorus and nitrogen that contaminate air, soils, and water.

What percentage of total animal production expense does feed typically represent?

$$65-70\,\%$$

Define a 'balanced ration'.

Food that contains all the nutrients an animal needs for maintenance and production in the correct proportions.

What is the difference between Act 36 of 1947 and Act 101 of 1965 in South African feed regulation?

Act 36 of 1947 (Stock Remedies Act) involves the registration of all feed products and ingredients under the Registrar of Farm Feeds, while Act 101 of 1965 (Medicines and Related Substances Control Act) controls the use of scheduled prescription products like antibiotics.

How does the water content of an animal change with maturity?

Newborn animals contain $750-800\,g/kg$ water, which falls to about $500\,g/kg$ in a mature fat animal.

What is the general ratio of water to dry matter (DM) consumed by animals?

Animals need about three times the amount of water for every $kg$ of DM consumed.

What is metabolic water, and what is the yield from the oxidation of fats?

Metabolic water (or oxidation water) is water available to the animal from metabolic processes; the oxidation of fats yields $100\,\%$ of its weight as water.

How is Crude Protein (CP) calculated from nitrogen content in the Kjeldahl analysis?

$$\text{Nitrogen (N)} \times 6.25 = \text{Crude protein (CP)}$$

What substances characterize the Crude Fibre (CF) organic residue?

Cellulose, lignin, and hemicelluloses.

For monogastric animals, what are the beneficial effects of crude fibre despite its low energy value?

It has water-holding properties that increase gut fill, which has beneficial effects on the behavior of pregnant sows.

Define Neutral Detergent Fibre (NDF) according to the Van Soest method.

NDF is a measure of plant cell wall material consisting of hemicellulose, cellulose, and lignin ($NDF = \text{Hemicellulose} + \text{Cellulose} + \text{Lignin}$).

What is the energy yield of fats compared to carbohydrates?

Fats are a concentrated source of energy that provide $2.25$ times the energy of carbohydrates.

Name the two essential fatty acids (EFA) that must be supplied in animal diets.

Linoleic acid (omega-6) and alpha-linolenic acid (omega-3).

What is a 'limiting amino acid'?

An amino acid present in the lowest amount relative to the requirements of an animal for a specific production purpose.

Which amino acids are most likely to be limiting in diets for mono-gastric animals?

Lysine, methionine, and tryptophan.

What is the difference between fibrous and globular proteins?

Fibrous proteins (like collagen and keratin) consist of elongated chains with structural roles and are insoluble and resistant to enzymes, while globular proteins (like enzymes and hormones) are folded into compact structures and are often water-soluble.

Define a 'conjugated protein' and provide an example.

A conjugated protein contains a non-protein moiety called a prosthetic group; examples include glycoproteins (with sugar) and lipoproteins (with lipids).

What are the five categories of lipoproteins, ordered by increasing density?

Chylomicrons, very-low-density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL).

In birds, what is the principal end product of nitrogen metabolism?

Uric acid (corresponding to urea in mammals).