Animal Nutrition: Food Analysis, Spectroscopy, and Carbohydrates

Comprehensive practice flashcards covering proximate analysis of feeds, principles of light and spectroscopy, historical microscopy, veterinary applications of the electromagnetic spectrum, and the classification and biochemistry of carbohydrates.

What is proximate analysis in the context of food and feed characterization?

A standard laboratory method used to determine the basic chemical composition of feed, evaluating key components such as moisture, ash, crude protein, ether extract, and crude fiber to assess nutritional value and formulate diets.

How is "ash" defined in proximate feed analysis?

The inorganic residue remaining after the complete combustion of a feed sample, representing its total mineral content.

What nutritional component does "ether extract" quantify in feed analysis?

The fraction of the feed that is soluble in ether, representing its energy-dense lipid and fat content.

What is "crude fiber," and how does it affect monogastric animals?

The indigestible portion of feed rich in cellulose and lignin that supports digestive motility and gut health but provides negligible usable energy to monogastric animals.

Why are humans and many non-herbivorous animals incapable of fully digesting fiber?

They lack the enzyme cellulase, which is required to hydrolyze the glycosidic bonds in cellulose.

What are the primary biological roles of amino acids and fatty acids?

Amino acids serve as the building blocks of proteins required for tissue repair, muscle growth, and enzyme synthesis, while fatty acids build lipids essential for long-term energy storage, thermal insulation, and cell membrane integrity.

What is spectroscopy?

The scientific technique that investigates how matter absorbs, emits, or scatters electromagnetic radiation across various wavelengths.

Why are green bacteria (such as Cyanobacteria or Chlorobium) visualized with higher contrast under green light rather than blue light?

Green bacteria absorb blue light and reflect green light; illuminating them with green light maximizes light reflection, making them appear significantly brighter and sharper.

Which historical figure is credited with the invention of the first compound microscope?

Zacharias Janssen, who invented it circa $1595$.

What historical instrument is shown in this image?

The first compound microscope (developed circa $1595$ by Zacharias Janssen).

What major breakthrough in microbiology was achieved by Antonie van Leeuwenhoek ($1632\text{--}1723$)?

Using high-power hand-ground single lenses, he became the first scientist to discover and describe microscopic organisms ("animalcules"), such as bacteria and protozoa.

Identify the standard laboratory instrument depicted in this diagram:

A compound microscope.

Why does a Transmission Electron Microscope (TEM) offer significantly greater resolution than a standard optical microscope?

It illuminates specimens using a focused beam of electrons, which possess much shorter wavelengths than visible light photons, enabling visualization down to atomic scales.

What is the function of immersion oil when using the $100\times$ objective lens on a compound light microscope?

It bridges the gap between the glass slide and the lens, matching their refractive index to minimize light refraction and scattering, thereby enhancing resolution and clarity.

Why is diagnostic ultrasound classified outside the electromagnetic spectrum?

Ultrasound relies on high-frequency mechanical sound waves rather than oscillating electric and magnetic fields.

How are microwaves utilized for medical therapy in veterinary practice?

Through microwave diathermy, which generates therapeutic deep tissue heating to ease muscular spasm, boost localized blood circulation, and accelerate tissue repair.

What causes sunburn, and how does its biological mechanism differ from visible light heating?

Sunburn is caused by ultraviolet (UV) radiation penetrating cutaneous layers and causing photochemical DNA damage that triggers painful inflammatory reactions, whereas visible light merely warms the skin.

Who discovered X-rays in $1895$, and what was his famous initial demonstration?

Wilhelm Roentgen discovered X-rays during cathode ray experiments and produced the first radiograph depicting the skeletal structure and wedding ring of his wife's hand.

What are two key applications of gamma radiation in veterinary medicine and animal science?

Sterilization of surgical instruments, feeds, and vaccines, as well as targeted radiation therapy for animal cancer.

How are carbohydrates classified according to the number of monomeric sugar units they contain?

Monosaccharides have $1$ sugar unit, disaccharides have $2$ units, oligosaccharides have $3\text{ to }10$ units, and polysaccharides have more than $10$ units.

Which nutritionist and researcher is pictured here?

Dr. John Yudkin, author of the 1972 book Pure, White and Deadly, who argued that dietary sugar rather than fat was the primary driver of obesity, diabetes, and cardiovascular diseases.

What common designations or "sugar nicknames" correspond to glucose, fructose, galactose, and sucrose?

Glucose is known as blood sugar or grape sugar; fructose is fruit sugar (the sweetest natural sugar); galactose is brain sugar; and sucrose is table sugar or cane sugar.

Why is honey capable of remaining preserved without spoiling for thousands of years, as seen in ancient Egyptian tombs?

Its high concentration of monosaccharides ($\approx 38\%$ fructose and glucose) exerts high osmotic pressure that dehydrates microbial cells, supplemented by the enzymatic production of antimicrobial hydrogen peroxide.

What is chemical isomerism in monosaccharides?

The condition where sugars share identical molecular formulas but possess different structural linkages (structural isomers, such as glucose vs. galactose) or spatial orientations (stereoisomers/optical forms like D- and L-enantiomers).

What distinguishes pentose monosaccharides from hexose monosaccharides?

Pentoses are five-carbon sugars essential for genetic material (such as ribose in RNA), while hexoses are six-carbon sugars (such as glucose and fructose) central to cellular energy metabolism.

What is a phosphoric acid ester of a monosaccharide, and what is its physiological role?

A sugar molecule covalently bonded to a phosphate group via an oxygen atom, functioning like a biological battery to activate substrates for metabolic conversions and energy transfer.

What monosaccharide subunits comprise sucrose, lactose, and maltose?

Sucrose consists of glucose $+$ fructose; lactose consists of glucose $+$ galactose; maltose consists of glucose $+$ glucose.

What is cellobiose?

A disaccharide composed of two glucose molecules joined by a $\beta(1 \rightarrow 4)$ glycosidic bond, serving as the repeating structural unit of cellulose.

What are raffinose and stachyose, and how are they classified?

Raffinose is a trisaccharide ($3$ sugar units) and stachyose is a tetrasaccharide ($4$ sugar units); both are oligosaccharides commonly found in beans and legumes that function as prebiotics.

What is the primary cellular role of adenosine triphosphate (ATP) produced during carbohydrate catabolism?

ATP is the primary high-energy chemical currency of living cells, supplying immediate energy to power muscular contractions, active transport, nervous conduction, and cellular repair.