Lecture 1 - Nutrients, Water & The Cell

GIT / GI / Alimentary Tract

Long tube from mouth to anus through which feed passes following consumption as it is subjected to various digestive processes

Prehension

Taking in of feed or water (grasping of food)

• Structures: lips, tongue (some ruminants)

Mastication

Reduction of feed particle size; generally by chewing.

• Structures: teeth, hard palate of mouth

Regurgitation

Casting up of undigested material

Digestion

Break down of feed particles into suitable products for absorption

Types of Digestion

1. Mechanical force

2. Chemical reactions

3. Enzymatic activity

Absorption

Transfer of substances from the GIT to the circulating blood or lymph system

Excretion

Removal of wastes

Anabolism

Growth or buildimg process

Catabolism

Breakdown or destruction reactions

Metabolism

Combination of anabolic and catabolic reactions occuring in the body with the liberation of energy

Substrate

A substance used in the support of nourishment

• Glucose, fiber, protein, peptide

Enzyme

A substance produced by a living organism which acts as a catalyst to bring about a specific biochemical reaction (usually the breakdown of substrates)

Nutrition

The process of gathering, processing, using, and responding to nutrients for health and growth

Nutrient

Any feed constituent that functions in the support of life

Malnutrition

Lack of PROPER nutrition

Causes of Malnutrition

• Not having enough to eat

• Not having enough of the right things to eat

• Not being biologically able to use the nutrients consumed

Bioavailability

The proportion of a substance that is able to be absorbed into general circulation

What % does livestock animal diet account for in production costs?

~70%

Why do we feed nutrients?

To get a desired response—performance

Most responses to nutrients are?

Quadratic

Measures of Growth

Pounds gained, feed efficiency, days on feed, average daily gain

Measures of Reproduction

Body reserves/condition, Conception rate, Milk production, Dystocia, Pregnancy abortion, egg/young production

Measures of Work/Fiber

Equine performance, hair/wool production

Measures of Immunity

Immune response and recovery rate

What are the 6 classes of Nutrients?

• Water - Moisture

• Carbohydrates - Dry matter, organic

• Protein - Dry matter, organic

• Lipids - Dry matter, organic

• Vitamins - Dry matter, organic

• Minerals - Dry matter, inorganic (ash)

Organic Matter

Compounds that contain carbon or carbon-hydrogen bonds

• Produced by or associated with living organisms

• Compounds that contain C, H, O, and N are classified as Organic.

Inorganic matter

Does not contain carbon.

• Produced or created by non-living organisms

What is ash?

The inorganic residue that remains after a feed sample is completely burned (combusted) at high temperatures.

• Also the principle behind the ashes collected after cremation

Of the 6 nutrient classes, water is the what? (3 notable things)

• Cheapest

• Most abundant

• Most essential

Deficiency of H2O is the last nurtient to cause death and performance reduction

FALSE!

• Deficiency will cause reduced performance and death before ANY other nutrient deficiency

• Loss of 20% of the body’s water reserve will result in death

Water content of body tissues (muscle, fresh bone, adipose)

• Muscle - 75%

• Fresh bone - 30%

• Adipose - 15%

Is water stored?

No, it is “turned over”

How long does a complete turn-over of water take?

~3 days

• Daily excretion must be matched with daily intake

How is water balance achieved?

By regulating electrolyte (mineral) concentration:

• Sodium, Chloride, Potassium, Magnesium, Calcium

What % of water is intracellular?

66%

Water is the principal component of the cytosol of every cell in the body.

True

In intracellular water, volume is ___ (tightly/loosely) regulated

Tightly

In intracellular water, concentration of what mineral(s) is high?

Potassium (K+)

What % of water is extracellular?

33%

Where is extracellular water located?

Between the cells (interstitial fluid) and in the fluid component of blood plasma

The volume of extracellular water is also tightly controlled with little fluctuation.

False—volume fluctuates with the total body water balance (dehydration/rehydration)

In extracellular water, concentration of what mineral(s) is high?

Sodium (Na+) and Chloride (Cl-)

Water sources in order of importance

1. Fresh drinking water

2. Water contained in food

3. Metabolic water

Metabolic water

Water produced from the catabolism (oxidative breakdown) or carbohydrates, lipids, or protein into energy

• C6H12O6 + 6O2 → 6CO2 + 6H2O + ~38ATP

Where does oxidative brakdown of nutrients for metabolic water creation take place?

Within the mitochondria of the cell

• Recall that oxidative breakdown creates energy and water, and the mitochondria are the primary energy producers of the cell!

Is metabolic water produced intracellularly or extracellulary?

Intracellularly, but is diffused into the extracellular space via concentration differences (high to low)

Nutrient molecules with greater ___ density produce greater metabolic water

• Hydrogen (H)

• Although lipids produce the most metabolic water/g of nutrient, there is greater heat production from lipid oxidation.

What animals typically derive their water from free water (drinking water)?

Livestock, companion, humans

What animals typically derive their water from food?

Marine mammals, fish, desert packrat, raptors

What animals typically derive their water from metabolic creation?

Desert kangaroo rat, birds during migration

• Rare, only occurs in highly specialized species (desert animals) or in specific situations

Functions of Water (6)

• Transporter of nutrients and waste

• Part of many metabolic reactions and dictates osmolality

• Gives shape to cells as a constituent of cytoplasm

• Lubricates and cushions joints and organs

• Acid-base regulation

• Maintenance of normal body temperature

Sensible water loss

Can be easily measured and detected

• Urine

• Feces

• Lactation

Insesible water loss

Cannot be easily measured; “water vapor”

• Lungs (ventilation)

• Skin (perspiration/sweating)

Increased dietary intake, protein, salt/mineral, and indigestible fiber cause an (increase/decrease) of water intake

Increased

The only dietary increase that causes a decrease in water intake is an increase of dietary what?

Moisture

What environmental or physiological factors cause an increase in water intake?

Temperature (hot and cold), gestation, lactation, work, disease

• Sweat is species dependent

What physiological factor can cause an increase and decrease in necessary water intake?

Age

• As age increases, water requirement increases

Lactating animals will require a much (less/greater) intake of water.

Greater as to recover the water loss that occurs during milk production

Only the quantity of water is important, not the quality.

False—both are important

What factors reduce water quality?

• Inorganic toxins (nitrates/nitrites, fluoride, heavy metals, some salts)

• Organic toxins (pesticides, hydrocarbons)

• Pathogenic organisms (bacteria, blue/green algae)

Total dissolved solids

Measures the proportion of minerals in water and should be tested when new wells are used.

• <1,000 ppm - safe for livestock and poultry

  • some animals may refuse or drink less

• 1k-3k ppm - satisfactory for livestock

  • may cause temporary mild diarrhea, animals may drink less

• 3k-5k ppm - unsatisfactory for poultry

  • will cause diarrhea and increase mortality for poultry

  • may cause diarrhea for livestock

• 5k-7k ppm - not suitable for poultry

  • high mortality for poultry

  • can be used with reasonable safety for livestock (not lactating or preg. females)

• 7k-10k ppm - avoid if possible

  • can be used for cattle, sheep or goats not subject to heat stress or water loss

  • Do not use for poultry, swine, horses or lactating/preg. females

• >10k ppm - not suitable for livestock

What factors reduce water quantity?

• Facility factors (confined animals—capacity, guarding/dominance, flowrate)

• Enviromental factors (drought, high heat → evaporation, freezing temperatures)

Animals faced with defiencies or restrictions in water may be subject to what?

• Reduced feed intake and, thus, lower productivity (noticable differences in 24 hours)

• Weight loss, constipation, stiff gate

• Increased excretion of nitrogen and electrolytes such as Na and K (cellular shrinkage and reduced cellular metabolism?

• Death within a few days

Dehydration is the primary reason for neonate and young animal death.

True

• From failure to nurse and separation from dam (mother) or water source

How is water absorbed in the GI?

Via passive diffusion

• Water flows from solutions of low osmolarity to high osmolarity (water follows salt)

• Large amounts of water are secreted into the GI each day and reabsorbed to follow the flow of nutrients

Cell Membrane

Selectively-permeable barrier that controls the entry and exit of substances.

• Entry and exit is controlled by the lipid bilayer, concentration gradients & membrane bound transporters

Cytosol

The fluid portion of the inner cell, mostly water (does not include the organelles or other insoluble materials).

• Allows for easy movement of molecules.

Nucleus

One per each cell. Contains hereditary material (DNA) and thus controls cell activities (via transcription) and mitosis (via DNA replication)

• Nucleolus: Site of the production and assembly of ribosome components

Ribosome

Complexes of RNA and protein that are responsible for polypeptide synthesis (eukaryotic ribosomes are larger than prokaryotes - 80S).

• The site of protein synthesis in the cell.

• Makes other organelles, enzymes & cell wall!

• There can be many of these in a single cell.

Mitochondria

A double membrane bound organelle. Site of aerobic respiration, which produces large quantities of chemical energy (ATP) from organic compounds like glucose.

• Mitochondria are only found in multicellular organisms.

• There can be many of these in a single cell.

  • A typical animal cell may have 1,000 to 2,000 mitochondria present.

  • The greater the density of mitochondrion in a cell from a particular bodily tissue, the greater the energy requirement that tissue has for productive purposes.

    • Ex: a heart cell has approximately 5,000 mitochondria per cell.

Endoplasmic Reticulum

A system of membranes involved in the transport of materials between organelles and shares part of it’s membrane with the nucleus.

• Smooth ER: Involved in the synthesis and transport of lipids and steroids, as well as metabolism of carbohydrates

• Rough ER: Studded with ribosomes and involved in the synthesis and transport of proteins to the Golgi apparatus.

Golgi apparatus

An assembly of vesicles and folded membranes involved in the sorting, modifying and packaging of proteins that can be used by the cell (in a lysosome) or secretes enzymes that can leave the cell by exocytosis.

Lysosome

Produced by the Golgi, the lysosome is an organelle of over 50 hydrolytic enzymes that degrade material taken up from outside the cell or digest obsolete components of the cell itself.

• The lysosome releases important enzymes in the process of Glycolysis as well as protein degradation.

Peroxisome

An organelle crucial for fatty acid synthesis and oxidation (when the body is using fat as a fuel source).

• Produces hydrogen peroxide (H2O2), a free radical, from oxidation, which is then decomposed by catalase to water and oxygen.

Catalase

An enzyme important for the control of free radicals by decomposing them into harmless substances, such as water and oxygen

Centrioles

Microtubule-organizing centers involved in cell division (mitosis)

Nutrition is intimately tied to the cell in the transfer of energy from one form to another for productive purposes.

True

The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another.

True