Animal Science Exam 1

What is animal science?

The study of domesticated animals

Equation for domestication

Genetic changes + Environmental influences

1st wave of domestication

8-15 thousand years ago, traditional species plus dogs and cats

2nd wave of domestication

Within last 100 years, new meat producers, laboratory animals, and fur animals

Food uses?

• Red Meat and Poultry

• Milk Products

• Eggs

• By-products

Significance of food

World population increasing, world hunger and malnutrition, enlarging diets of people

Other animal contributions

• fabric/fibers

• power source

• body wastes

• pest/weed control

Cultural significance?

• companionship

• sports and exhibition

• religion

What makes beef cattle uniquely valuable?

They are able to convert resources that humans cannot digest to high-quality protein

Why can humans not digest forage like cows?

We lack cellulase to break down cellulose

Cattle have:

• 4 part ruminant stomach

• a large rumen

• microbial populations that ferment fiber

Ways beef cattle help the environment:

• utilizing land that is not suitable for crop production to graze instead

• consuming waste material like cornstalks and wheat straw

• also sweet stuff like corn cannery waste and sugar beet pulp

3 Structures of the beef industry

1. Cow-Calf operation

2. Stocker Phase

3. Feedlot system

Cow-calf operation

• calves are produced and feed off pasture/forage plus mother

• ends around 6-10 months and 300-700 lbs

Stocker Phase

• growth of a calf after weaning

• fed pasture and forage

• goal: INCREASE BODY WEIGHT

Feedlot system

• maximize muscle growth and fat deposit on adults

• fed either grain-based ration OR grass/pasture to reach market weight

• Slaughtered at 18-22 months

tradeoff for grass-finished beef

+uses more pasture (cheaper)

-slower growth and return on investment

tradeoff for grain-finished beef?

+rapid weight gain

-more expensive to feed

What makes dairy cattle uniquely valuable?

Convert forage and nutrients into milk

Why does a modern dairy cow produce more milk needed to nourish their calf?

• selective breeding

• human demand

Dairy Cow Lactation Cycle

1. milk production begins when a cow gives birth

2. milk production increases rapidly

3. milk production peaks between 6-13 weeks after birth (bred again here)

4. Gradual decline

5. Dry period before next calving

How are dairy calves managed?

• removed from mom at birth

• housed individually most the time

• fed milk until weaned at 60 days

How are dairy heifers managed?

• considered heifers after weaning

• fed mostly forage

• bred at 2 years

How are lactating cows managed?

• Considered a cow once they give birth

• Milked every day except during dry period

• last typically 3 lactation cycles

Tradeoffs in dairy production?

+makes tons of milk

-expensive (requires machines, feed, water)

-greater metabolic stress

what makes sheep uniquely valuable?

They’re adaptable to challenging environments and multipurpose

Sheep products

• wool

• meat

• milk

• grazing services

How are sheep grazed differently than cattle?

• eat shorter vegetation

• are more selective in their grazing

• consume plants cattle tend to avoid

Advantages of wool production?

• overall sustainable

• sheep shorn annually

• can be done over the entire span of a sheep’s life

What makes chickens uniquely valuable?

They’re very efficient and produce inexpensive proteins

What are the two kinds of chicken?

Layer and Broiler

Chicken diet?

• Nutrient-dense feed

• cannot digest large amount of forage like others

• pellets made of corn/wheat/barley

Advantages of chickens?

• Reach market weight quickly

• require less space

• Has most progress; breeding and selection techniques

Give some detail on the broiler industry.

• Most broiler production concentrated to parent companies and their farms + operations (usually in the southeastern states)

• low cost labor

• especially profitable near cities

Give some details on the egg industry

• a laying hen can produce 100s of eggs annually

• most eggs in commercial operations do not touch human hands till removed by consumer

• more dispersed than broiler production

What makes pigs uniquely valuable?

They have large litters and grow rapidly

Describe the pig life cycle.

1. Birth

2. Suckling

3. Weaning @ 8-9 weeks

4. Growing @ 9-16 weeks

5. Finishing @ 16-25 weeks

6. Slaughter @ any age (porkers at 30-54kg baconers at 24+ weeks)

Swine industry structure

• more pigs owned by fewer people (like chickens)

• farms centered near the cornbelt of the US (gain production heavy in these places)

Advantages of pigs?

• more animals to market

• faster herd expansion + return on investment

• housed indoors

How does the body use nutrition?

• Maintenance

• Growth

• Work/production

• Reproduction

What’s the difference between essential and non-essential nutrients?

Essential - must be obtained in diet

Non-essential - synthesized in the animal

what is essential/non-essential varies by species

What are the 6 classes of nutrients?

1. Carbohydrates

2. Lipids

3. Proteins

4. Vitamins

5. Minerals

6. Water

Give an example of a carbohydrate

Starch, sugars, cellulose

What are the major classes of carbohydrates?

Mono, Di, and Polysaccharides

Uses for Carbohydrates

Fuel, molecular skeletons, plant cell walls

What are the major classes of lipids?

• Triglycerides

• Fatty acids (sat and unsat)

• Phospholipids

• Steroids

Uses for lipids?

• Fuel (2.5x more than carbs)

• Cell membranes

• vitamin storage

• hormone synthesis

Triglyceride structure?

glycerol + 3 fatty acids

Major classes of proteins?

Essential and non-essential amino acids

Uses of proteins?

• structures (muscle)

• biochemical processes

• energy (though less than carbs and fats)

Essential amino acids

AAs that cannot be synthesized in the animal and must be provided via diet

Limiting amino acids/ Law of the minimum

Growth is controlled not by the total amount of amino acids available, but by the single AA in shortest supply

What are the major classes of vitamins?

Water soluble and fat soluble

What are vitamins used for?

• catalysts in biochemical reactions

• many regulatory functions

Fat soluble vitamins

A,D,E,K

Water soluble

B, C

What are the major classes of minerals?

Macro and Micro

Uses of minerals?

• catalyze biochemical reactions

• physical structures

Examples of minerals?

Calcium, phosphorus, potassium, sodium & chloride, sulfur, magnesium

Calcium

bones and teeth

Phosphorus

RNA/DNA

Potassium

electrical impulses of heart and other cells

Sodium & Chloride

controlling your blood pressure and blood volume

Sulfur

important for some proteins like insulin which regulates blood sugar

Magnesium

important for biochemical reactions in the body

Examples of micro-minerals?

zinc, iodine, iron, flourine, cobalt, selenium

What leads to white-muscle disease?

Vitamin E and selenium deficiency

How can water be obtained?

Drinking it or from moisture in food.

What is water used for?

metabolic reactions, transport, temperature regulation, shape

insufficient salt in the blood, often occurs when an animal is playing in or with water for long periods of time and ingests too much

Hyponatremia

“bone-eating”; common in herbivores when soil or plants are not sufficient in phosphorus, so they seek calcium phosphate by chewing on bones

Osteophagia

What are the five components of proximate analysis?

1. Moisture - 12%

2. Ash (inorganic matter) - 5%

3. Protein - 13%

4. Fat - 4%

5. Crude fiber - 10%

What are the functions of the digestive system?

1. Receiving

2. Conducting, storing

3. absorption, digestion

4. absorbing water, defecating

What are the events of digestion?

1. Physical

2. Chemical

3. Enzymatic

physical digestion

• Prehension (grabbing)

• Mastication

• Salivation

• Deglutition (swallowing)

• Peristalsis (muscle in esophagus contracting food as it travels down the throat in wave-like movements)

OCCURS IN THE MOUTH

Chemical digestion

• hydrochloric acid denatures proteins

• bile helps digest fat

OCCURS IN THE STOMACH

Enzymatic

• breaks bonds; organs, intestines, and microbes

OCCURS IN SMALL AND LARGE INTESTINE

Small intestine parts

Duodenum, jejunum, Ileum

Helps neutralize stomach acid and aid enzymatic digestion in the SI

Duodenum

Aids digestion and absorption in SI

Jejunum

helps absorption in SI

Ileum

Parts of the Large Intestine

Colon, cecum, and rectum

Absorbs water and forms feces

Colon

blind pouch, site of fermentation in some species

cecum

connects colon to anus

Rectum

ruminant mouth

no upper teeth

oral cavity

• acquires food

• initial mechanical breakdown

• tongue muscle helps movement of food

esophagus

• Moves food boluses from the mouth to the stomach through “peristalsis”

• Ends at the lower esophageal sphincter

• Prevents food and acid from the stomach from flowing backwards into the

esophagus

• Very muscular

stomach - monogastric

• single stomach

• autoenzymatic digesters (enzymes secreted by the animal itself

are involved in the digestive processes)

• limited capacity

• located near the head

stomach - ruminant

• 4 compartments with high capacity

• microbial fermentation

what are the 4 compartments of ruminant stomachs

• rumen

• reticulum

• omasum

• abomasum

Rumen

Fermentation vat, absorbs nutrients, microbial fermentation

Reticulum

Traps dense objects, sorts particles into those that need more digestion

Omasum

Fluid removal, water and nutrient absorption

Abomasum

“True stomach”, HCl and enzymes breakdown food material

Monogastric animals

Pigs, dogs, chickens

Mucus neck cells

secrete mucus

paretial cells

secrete HCl

chief cells

secrete enzymes

gallbladder

secretes bile to assist with lipid absorption