ANSC 301 Final Exam

Main environmental gas from livestock

Methane

what % of global greenhouse gases are from livestock?

11.1%

What animals produce the most methane

Ruminants

Methane atmospheric lifetime

about 12 years

Methane warming potential vs. CO2

25x stronger

Main source of methane in livestock

burping

Purpose of methane digestion

binds free hydrogen from fermentation

What does CRISPR-Cas9 stand for

clustered regularly interspaced short palindromic repeats + Cas9 protein

When is CRISPR applied in livestock

embryonic stage

Main function of CRISPR

modify or inactivate genes

Disease resistance improved with CRISPR

PRRS and tuberculosis

Production traits improved with CRISPR

muscle growth and heat tolerance

Example of allergen-related genetic modification

hypoallergenic eggs

health risk linked to red meat

heart disease, high saturated fats, high cholesterol, and cancer risk

Benefits from red meat

protein, iron, zinc, and B vitamins

% of land used for pasture/rangeland

29%

% land used from cropland

17%

Cause of deforestation in livestock systems

grazing or crop production

Cause of soil degradation in livestock

overgrazing

Water issue from livestock production

water pollution

Key factors in animal housing

space, temperature, ventilation, manure management, and floor conditions

What is Prop 12

California law setting minimum space requirements for livestock

Purpose of subtherapeutic antibiotics

increase growth and improve feed efficiency

Requirement before treated animals enter the food chain

Withdrawal period

Major concern with antibiotic use

Antibiotic resistance

Environmental benefit of improved efficiency

Less land use and manure production

% of feedlots using growth implants

70-80%

ADG improvement from implants

5-15%

Feed efficiency improvement from implants

5-10%

Estrogen in implanted beef (per lb)

about 11 ng

Estrogen is non-implanted beef (per lb)

about 8 ng

Estrogen in ice cream (per lb)

about 3000 ng

Key takeaway about estrogen in food

food levels are tiny compared to human production

What are beta-agonists

repartitioning agents that increase lean muscle

Beta-agonist example in cattle

optaflexx

Beta-agonist example in swine

paylean

Why are beta-agonists controversial

Residue concerns and international bans

Three major challenges in livestock production

environment, animal welfare, public perception

Challenges with new technologes

Ethics, regulation, consumer acceptance

Future goal of the livestock industry

balance productivity, sustainability, and public health

Key factors impacting lamb yield and quality

genetics, nutrition, and environment

What type of growth do meat breeds have?

Rapid growth and desirable carcass composition

Examples of wool meat-type breeds

Suffolk, Hampshire, Shropshire, Texel

Example of hair sheep breeds

Dorper, Katahdin

Sex type that is heavier, leaner, and less mature

Intact males (rams)

Sex type that matures earlier and is fatter

Females

Sex type with intermediate traits

Wethers (castrated males)

What are EBVs used for

Estimate genetic potential of an animal

EBV example (growth trait)

Weaning weight (WWT)

EBV example (carcass trait)

Fat depth or ribeye depth

What is heritability

proportion of trait variation due to genetics vs environment

reproductive trait heritability

low (5-20%)

Growth trait heritability

low to moderate (10-40%)

Carcass trait heritability

High (30-45%)

If trait is not genetic, what explains it

the environment

Three lamb finishing systems

forage only, pasture and grain finishing, and pelleted feed

Flavor from forage-finished lamb

stronger/gamey flavor

Risk of high-grain diets

Softer fat, rancidity, off flavors

Health risk of high-grain diets

Acidosis

Minimum forage needed in diet

about 10%

What determines growth rate in lambs

dietary energy and protein

meat tenderness difference between fast vs. slow growth

very similar tenderness

what happens with excess dietary energy?

more fat deposition

Type of fat increased with excess energy

External (backfat)

What is backfat thickness measured over

ribeye at 12th rib

Normal backfat thickness range

0.005-0.5 inches

Where is body wall measured

between 12th-13th rib about 5 inches from midline

Body wall includes what

Rib and fat

Body wall range

0.6-1.2 inches

What is ribeye area

area of longissimus muscle

Ribeye area average

about 2.8 sq in

Effect of heavier carcass weight

decreases value

effect of more backfat

decreases value

Effect of thicker body wall

decrease value

effect of larger ribeye area

increase value

What is yield grade based on

backfat thickness

what does a lower yield grade mean

leaner carcass, higher yield

What is flank streaking used for

to determine quality grade

Two maturity categories in lamb

A maturity, B maturity

What are spool joints used for

determine maturity

What develops last in carcass maturity

Spool joints

Goal of EPDs

Predict offspring preformance

Economic index

multi-trait value in $

Ideal herd goal

1 calf per cow per year

% calf crop formula

(calves weaned/ cows exposed) *100

Calving interval

about 365 days

Scrotal circumference indicates

fertility/puberty

Weaning weight shows

milk + growth

Birth weight issues

High=dystocia

Best predictor of value

yearling weight

Production EPD example

BW, WW, YW

Maternal EPD example

milk, heifer pregancy

Carcass EPD example

marbling, ribeye, fat

Litter size measures?

reproduction

21-day litter weight shows?

mothering ability

Structural correctness importance?

longevity

Capacity

Rib=performance

Too fat cows

Poor reproduction

To think cows

Low conception

Phenotype=

Genotype + environment