Exam 4 - Animal Science

Animal Genetics

Branch of biology that deals with heredity and variation

Phenotype (P)

What you see in an animal

Genotype (G)

Genes the animal has

Environment (E)

How and where the animal is raised

P = G + E

Phenotype is influenced by genetics and environment

Chromosomes

Animals receive one set from sire and one from dam

Segregation

Only one gene from a pair is passed to offspring

Independent assortment

Genes for different traits separate independently

Gene action

How genotype affects phenotype expression

Complete dominance

Dominant gene masks recessive gene

No dominance

Heterozygous is intermediate between homozygous

Additive gene action

Many genes contribute to a trait

Non-additive gene action

Single gene controls trait

Sex-linked traits

Traits controlled by genes on X chromosome

Sex-limited traits

Traits expressed only in one sex

Sex-influenced traits

Traits expressed differently in males vs females

Artificial selection

Humans choose which animals reproduce

Natural selection

Environment determines survival and reproduction (survival of the fittest)

Genetic merit

Estimated potential of an animal’s traits

Single trait selection

Selecting based on one trait

Multiple trait selection

Selecting based on a group of traits

Inbreeding

Mating closely related animals

Inbreeding effect

Exposes hidden recessive traits

Crossbreeding

Mating animals of different breeds

Heterosis

Hybrid vigor where offspring outperform parents

Complementarity

Combining strengths of different breeds

Cloning

Creating an exact genetic copy of an animal

Dolly the sheep

First cloned mammal in 1997

Gene editing

Changing an animal’s DNA to get desired traits

CRISPR

Precise gene editing technology

Transgenic

Genes added from a different species

Genetic engineering

Using technology to modify genes

ATryn goats

Genetically modified goats producing human protein

Hornless cattle (gene editing)

Eliminates need for dehorning

GalSafe pigs

Genetically modified pigs safe for people with alpha-gal allergy

PRRS

Costly swine disease targeted by gene editing

PRRS-resistant pigs

Genetically edited pigs resistant to disease

Dairy Cows Facts

About 10% of all cows in the US are dairy cows

State with Top Number of Herds

Wisconsin

State that is Top Milk Producing

California

Why is Wisconsin not the top producing state

Wisconsin = many small

California = few but massive

Product Classification: Fluid Milk

Beverage milk and cream

Product Classification: Component Priced Milk

Milk that would be used for dairy products

Why do different state focus on different things?

Federal milk marketing orders (FMMOs)
Supply and Demand
Transportation of product

Which cow is superior for milk

Holstein Cow

Which cow is superior for milk fat?

Jersey Cow

Cow life cycle events

Parturition, rebreeding, gestation, dry, parturition

Holstein cows are the (?%) of cows

86%

First calves at how many months of age

25 months

Average lactation is how many days

336 days

Dry for how many days

57 days

How many years does a cow produce milk

5 years

Reasons for culling

Reproductive failure, udder breakdown, low milk yield, and mastitis

How many times a day are cows milked

twice a day

Milk Let Down

the hormonal process (triggered by oxytocin) where breastmilk is released from the milk glands into the ducts, causing it to flow or spray

Milking Process

Tandem Parlor-
Parallel Parlor
Herringbone Parlor
Rotary Parlor - round circle

Milking Process

Disinfect, Observe the foremilk, wipe dry, attach unit, milking, shut off vacuum, disinfect

Pasteurized milk

heated to more than 160 degrees F for 15 seconds

Homogenization

Homogenization breaks fat particles into tiny pieces that stay in solution

Cheese

Product obtained from the coagulation of caseins and the separation of whey

Butter

Product obtained from the separation of the milkfat

Yogurt

Product obtained by the fermentation of milk

Ice Cream

Obtained by freezing of cream/milk

Top World Cattle Producer

India, Brazil, China

Top World Beef Producers

USA, Brazil, EU

Top World Beef Consumer

Uruguay, Argentina, China

Proteins in milk

caseins and whey

Raw milk

In most states, it is illegal to sell at a store. Can contain dangerous bacteria.

British Breed

Breed originated in the British Islands
Angus, Hereford, and Shorthorn

Continental Breed

Zebu Breed

Orginated from South Asia
Brahmen, Black Baldy, Brangus (Angus and Brahmen mix)

Seed Stock

Specialized cow-calf producers. Provide the genetic material used by commercial cow-calf producers.

Cow-Calf

Maintain cowherds and raise calves from birth to weaning
Ideally one calf per year

Stocker

add weight to weaned calves prior to entering the feedlot. 100% of their diet is forages.

Feedlot

(When used for beef) Confined feeding operations where cattle are fed a finishing (high energy) diet. Most are there for 100-200 days.

Grain Finished

Eating grass, but for the last days of their life they are eating grains. More tender meat. Low carbon footprint

Grass Fed

not nutrient dense diet, so it takes them more than 2 years to get to that finish weight.
Increase age = increase connected tissue = decrease in tenderness
Higher carbon footprint

Grassfed vs Natural vs Organic

Grassfed - American Grassfed Assosiation
Natural - final product, no artificial additives, minimal processing
Organic - No artificial fertilizers, pesticides,

Packer

Slaughter and process the cattle. Beef is boxed by the packer

Quality Grade

Prediction of the palatability
1. Age of the animal
2. Intramuscular fat

Yield Grade

Estimated proportion of the primary retail cuts from a carcass
Proportion lean; fat

Consumer Preferences

Prefer juicy, flavorful, tender beef.

Marbling

is used to establish USDA Quality Grades

Cuts of Beef

8 primal cuts

8 Primal Cuts (name the four main ones)

• chuck

• rib

• loin

• round

Turkey Breeds

Bronze, Bourbon, White, and Narragansett

Geese Breeds

Brown Chinese, White Chinese, African grey, Pilgrim

Duck Breeds

Broiler Production

Chickens that are raised for meat production

Chicken breed prominently used

White Cornish

Top 10 countries ranked by chicken population

USA, China, Indonesia

Leading state in chicken production

GA

Vertical Integration

a business strategy where a company gains control over multiple, consecutive stages of its supply chain, rather than relying on external suppliers or distributors

Breeder Flock

Bedding (straw), Nest Boxes, Feed, Water

Hatchery

Incubate and hatch chicks. incubation for 21 days. 99-100 degrees and 58% humidity

Shipping

1-3 days post hatching. Yolk Sac- provides enough nutritional value for up to 3-5 days

Grow out farm

Growth of chicks, high biosecurity level (very fragile), all-in all-out system (all come in and all leave, helps sanitation)

Life Cycle - Broilers

Breeder flock (produce eggs), Hatchery (21 days), Shipping (1-3 days), Grow out farm (5-7 weeks), Harvest broilers, sanitation (14 days)

Hen Production

Chickens for egg production

How many eggs does a white leghorn produce per year

300