Animal Nutrition Quiz 1

Animal Nutrtion

Nutrition

Interrelated steps by which living organisms use nutrients for maintenance and production.

Nutrients

Individual chemical compounds or elements in the diet used for maintenance and production.

Maintenance

Nutrient supply needed to support organ function and sustain life.

Production

Nutrient supply in excess of maintenance to support growth, lactation, reproduction, and exercise.

Six classes of nutrients

Carbohydrates, water, protein, minerals, lipids (fats), and vitamins.

Organic nutrients

Carbohydrates, protein, lipids, and vitamins.

Inorganic nutrients

Minerals and water.

Energy-providing nutrients

Carbohydrates, lipids, and proteins.

Essential nutrient

A nutrient not synthesized by body tissues in adequate amounts.

Nonessential nutrient

A nutrient synthesized by body tissues.

Three sources of nutrients to body tissues

Diet, tissue synthesis, and synthesis by gut bacteria.

Establishment of nutrient essentiality

Removing a nutrient from the diet and observing for defects.

Biochemical defect

An enzyme is not functioning.

Functional defect

Accumulation of substrate or deficiency of product.

Microscopic functional defect

Tissue damage.

Macroscopic functional defect

An outward physical abnormality.

Five-step progression of nutrient deficiency

Biochemical defect \rightarrow functional defect \rightarrow microscopic functional defect \rightarrow macroscopic functional defect \rightarrow death.

Thiamine

A nutrient required for thiamine pyrophosphate (TPP) to function.

Thiamine pyrophosphate (TPP)

Coenzyme required to convert pyruvate to acetyl CoA.

Nutrient deficiency

Condition where nutrient supply is insufficient to meet basic requirements.

Marginal nutrient supply

Nutrient supply below the amount needed for optimal performance.

Optimal nutrient supply

Nutrient supply that meets requirements and supports maximum performance.

Excess nutrient supply

Nutrient supply above the optimal amount without causing toxicity.

Toxic nutrient supply

Nutrient supply high enough to cause harmful effects.

Factors affecting nutrient requirements

Species, breed, body weight, and gender.

Proximate analysis

A system that subdivides feed into the six nutrient groups.

Moisture (proximate analysis)

Water content of feed.

CP (Proximate Analysis abbreviation)

Crude protein.

CF (Proximate Analysis abbreviation)

Crude fiber.

EE (Proximate Analysis abbreviation)

Ether extract (fat).

Ash

Mineral content of feed.

NFE (Proximate Analysis abbreviation)

Nitrogen-free extract; represents the carbohydrate portion including starch and soluble sugars.

Crude protein conversion equation

$$\text{g CP} = \text{g N} \times 6.25$$

Crude protein analysis limitations

Not all protein contains 16% nitrogen, and not all nitrogen comes from protein.

NFE formula

$$\% \text{NFE} = 100 - \% \text{CP} - \% \text{H}_2\text{O} - \% \text{CF} - \% \text{Ash} - \% \text{EE}$$

NDF (Neutral Detergent Fiber)

Structural components consisting of hemicellulose, cellulose, and lignin.

ADF (Acid Detergent Fiber)

Structural components consisting of cellulose and lignin.

Primary use of NDF

Predicting dry matter intake.

Primary use of ADF

Predicting forage digestibility.

Bioenergetics

The study of energy processing and transformation in living organisms.

Energy

The potential to perform work.

Calorie

The amount of heat energy required to raise the temperature of one gram of water by one degree Celsius.

Kilocalorie (kcal)

$$1{,}000\,cal$$

Megacalorie (Mcal)

$1{,}000{,}000\,cal$ or $1{,}000\,kcal$

Joule (J)

The international standard unit of energy.

First Law of Thermodynamics

Energy can be transformed from one type to another, but cannot be created or destroyed.

Chemical potential energy

Energy stored within chemical bonds, such as in food and body fat.

Gross energy (GE)

Total energy consumed in food, measured as heat of combustion.

Digestible energy (DE)

Gross energy minus fecal energy loss.

Metabolizable energy (ME)

Gross energy minus energy lost in feces, urine, and gas.

Net energy (NE)

Energy remaining after fecal, urinary, gaseous, and heat increment losses.

Energy retained (ER)

Energy stored as body protein, body fat, body carbohydrates, milk, eggs, or fetus.

Net energy for maintenance

Portion of net energy used to keep the animal in energy equilibrium.

Net energy for production

Portion of net energy used for growth, tissue gain, milk, or work.

ME calculation formula

$$\text{ME} = \text{GE} - \text{feces} - \text{urine} - \text{gas}$$

NE calculation formula

$$\text{NE} = \text{ME} - \text{heat}$$

Total Digestible Nutrients (TDN)

A measure of the digestible portion of feed energy.

DCP

Digestible crude protein.

DNFE

Digestible nitrogen-free extract.

DCF

Digestible crude fiber.

DEE

Digestible ether extract.

TDN calculation formula

$$\text{TDN} = \text{DCP} + \text{DNFE} + \text{DCF} + (\text{DEE} \times 2.25)$$

Reason DEE is multiplied by 2.25 in TDN formula

Fat contains 2.25 times more energy density per unit weight than carbohydrates.

ME conversion formula from TDN

$$\text{ME (Mcal/kg)} = \text{TDN (\%)} \times 0.0361$$

Direct calorimetry

Measurement of energy expenditure by directly measuring heat emitted from the body.

Indirect calorimetry

Measurement of energy expenditure determined through respiratory gas exchange.

Basal metabolism

The minimal amount of energy expended to sustain life in an animal.

Three conditions for measuring basal metabolism

Resting state, fasting state, and thermoneutral environment.

Heat of activity

Heat generated by physical actions such as standing, sitting, or moving.

Heat increment

Increase in heat production following food ingestion, excluding heat of fermentation.

Three causes of heat increment

Muscular activity of digestion, digestive secretions, and metabolic processing by cells.

ATP

Primary cellular energy carrier that captures released energy.

Substrate-level phosphorylation

Direct synthesis of ATP from ADP and a reactive intermediate, independent of the electron transport chain.

Oxidative phosphorylation

Synthesis of ATP driven by electron transfer reactions through the electron transport chain.

Location of the electron transport chain

Inner mitochondrial membrane.

ATP yield of electron transport chain

$$32\text{ ATP}$$

Net ATP yield of glycolysis

$$2\text{ net ATP}$$

Four physical mechanisms of heat loss

Vaporization, conduction, convection, and radiation.

Vaporization

Heat loss via the conversion of liquid water to vapor.

Latent heat of vaporization of water

$$580\,cal/g$$

Poikilotherms

Cold-blooded animals that regulate body temperature primarily via physical/environmental means.

Homeotherms

Warm-blooded animals that regulate body temperature via chemical metabolic heat production alongside physical means.

Thermoneutral zone

Ambient temperature range where body temperature is maintained without altering basal metabolic rate.

Lower critical temperature

The environmental temperature below which metabolic rate must increase to maintain body temperature.

Upper critical temperature

The environmental temperature above which evaporative cooling fails to prevent internal body temperature rise.

Summit metabolism

Maximum attainable metabolic heat production used to prevent hypothermia.

Metabolic response below the thermoneutral zone

Heat production increases above basal metabolic rate to retain thermal homeostasis.

Metabolic response above the thermoneutral zone

Evaporative cooling mechanisms (e.g., sweating, panting) are deployed.

% Water formula

$$\% \text{Water} = \left(\frac{W_i - W_f}{W_i}\right) \times 100$$

% Dry Matter (% DM) formula

$$\% \text{DM} = 100 - \% \text{Water}$$

% Crude Fiber (% CF) formula

$$\% \text{CF} = \left(\frac{W_f}{W_i}\right) \times 100$$

% Fat formula

$$\% \text{Fat} = \left(\frac{W_i - W_f}{W_i}\right) \times 100$$

% Ash formula

$$\% \text{Ash} = \left(\frac{W_f}{W_i}\right) \times 100$$