selecting swine - kelley anne...

Selecting Swine

TEKS: 130.2(C)(12)(D)

Objectives

• List 3 ways to evaluate swine;

• List traits we can visually evaluate;

• Label the parts of a pig;

• Describe what we should look for in structure

from a side view;

• Describe what angle a pig’s pastern should sit

at;

• Explain why we should select against uneven

toes;

Objectives

• Describe how the hind legs on a pig should

stand;

• List 5 structural faults we should select

against;

• Explain how proper angularity in the legs and

maximum cushion benefits the hog;

• Explain why we should select for pigs that

have volume and dimension of rib and body

cavity;

Objectives

• Explain why natural curvature in the rib cage

is important for sows and gilts;

• List 3 areas we can easily find fat disposition

at;

• Identify areas where muscle is expressed at;

• Distinguish correct and incorrect underlines

from multiple different pictures;

• Identify what PSS stands for;

• Solve a Pearson square problem for PSS;

Objectives

• Identify indications of PSS;

• Define PSE;

• Define DFD;

• Label the cuts of a hog carcass;

• Define what a Pedigree is;

• Identify what EPD stands for; and

• Choose the best boar out of 4 that you would

pick to be in your herd.

Photo by Tim McCabe courtesy of USDA Natural Resources Conservation Service.

Introduction

• What do you want to produce?

• Market animals?

• Breeding animals?

Introduction

• Market hog

– Combination of carcass & production traits

• Breeding hog

– Combination of carcass & production traits

– Reproductive & breeding potential

Select for…

• Structurally sound

• Healthy

• Big volume

• Thick muscled

• Efficient type

Ways to Evaluate…

• Visual

• Performance data

• Pedigree evaluation

Short Generation Interval

• Allows for rapid change

• Swine – 2.5 litters per year

• Cattle – 1 calf crop per year

• Sheep – 2 litters per year

Visual Evaluation

• Skeletal Correctness

• Capacity

• Leanness

• Muscling

• Size & Scale

• Sex Character

• Health

• Breed Character

Parts of a Pig

Back

Neck

Shoulder

Loin Rump Tail

Ham

Hock

Dew Claw

Toe Stifle

Rear Flank

Belly or Underline

Fore Flank

Elbow Pocket

Pastern

Knee Jowl

Snout

Length of Side

Photo by Gene Alexander courtesy of USDA Photography Center.

Skeletal Correctness

• Raised under Confinement Conditions

– Concrete

– Wire mesh

– Slatted floors

Structure

• Unsoundness of leg or feet get worse under

confinement

• Structurally correct hog has cushion in the

bones & joints

Structure

• From side view

– Long-bodied

– Strong, level top & rump

– High set tail

• Select against:

– Arch to the topline

– Shoulder blades pushed forward

Structure

• Angle on forelegs should approach 90 degrees

• Pastern angle – 60 to 45 degrees

– Provides maximum shock absorption

Hind legs should have similar

angularity.

Structure

• View from front:

– Straight-legged

– Adequate bone

– Toes even in size

• Short toe will cause

abnormal wear on the

other toe

• Results in lameness

Structure

• View from behind

– Stand squarely on rear legs

– Hind feet should toe out slightly

Structural Faults

• Post-legged

• Buck-kneed

• Straight pasterns

• Cow-hocked

• Sickle-hocked

• Splay-footed

• Pigeon-toed

• Swollen joints

• Crooked or Uneven toes

Structure

• Proper Angles + Maximum cushion =

Adequate shock absorption & balanced weight

distribution

Capacity

• Moderate depth of body

• Moderate length of leg

– Extremely long or short legs & shallow bodies are

undesirable

• Volume & Dimension of rib & body cavity

– Allows for adequate feeding & breeding capacity

Photo from IMS.

Capacity

• Equally deep in fore & rear ribs

• Long-bodies

• Moderate depth in rear flank

Capacity

• Natural Curvature of Rib Cage is important!

• Flat rib shape

– Hinders female from rolling onto feet while in

farrowing crates

Leanness

• Highly heritable trait!

• Consumer demands lean meat!

• Lean down top & over loin edges

• Show adequate shoulder blade movement as

they walk

Photo from IMS. Photo from IMS.

Areas for Fat Disposition

• Rib cage

• Jowl

• Elbow pockets

• Fore & Rear flanks

• Underline

• Seam & base of ham


Round top = leanness

Square top = excessive fat

Muscling

• Muscle + Leanness =

most important

components!

• Highly heritable!

• Observed in live animal

• Expressed in:

– Shoulders

– Top (back)

– Loin

– Rump

– Ham

Muscling

• Shape & Expression are important when

selecting!

Extremeness in muscle may result in undesirable

reproductive & mobility problems

Size & Scale

• Selecting lean, large-frames, long-bodied

animals ensures they will produce faster &

more efficient market hogs for offspring.

• Should be “market-ready” @ 240-280lbs

– w/o slowing down in growth

– w/o depositing excess body fat while reaching

heavier weights

1. Clean jowl

2. Expressive top

3. Trim middle & underline

4. Muscular ham

5. Good leg structure (front & rear)

1. Wide, expressive hams

2. Correct turn & shape to top

3. Clean, trim crotch

4. Bulge & expression of muscle

In stifle region

1. Wide shoulder

2. Lean turn to top

3. Expression of muscle

down the top

4. Flare of ham from top view

Ideal Market Hog

Sex Character

• Boar? Barrow? Gilt? Sow?

• Subjective measurement of physical traits

• Indicates masculinity in boars & femininity in

gilts & sows

Photo from IMS.

Boars

• Adequate testicle development

• Rugged but not vicious appearance

Boars

• Select against masculinity at a very young age!

– Sign of early maturity

– Excess finish or fat when they reach market weight

Photo from IMS.

Females

• Moderately refined

• Clean jowl, neck & head

Females

• Fully development & properly positioned

vulva

– Permits ready penetration by boar during mating

• Undeveloped vulva indicated:

– Poorly developed reproductive tract

– Poor fertility

Underline

• Highly heritable

• For both boars & gilts!

• At least 12 teats

– 6 on each side

– Prominent

– Uniform in size

– Evenly spaced

Photo by Ken Hammond courtesy of USDA Photography Center.

Even spacing allows for larger

udder sections & more mammary

tissue that consequently will

produce more milk.

Correct or Incorrect?

Photo courtesy of USDA Photography Center.

Health

• Constitution – general overall hardiness &

ability to withstand adverse conditions

Constitution

• Indicated by:

– Stoutness of head

– Fullness of heart girth

– Depth of forerib

– Width of chest floor

– Ample amount of bone

– Strength & soundness of feet & legs

PSS

• Porcine Stress

Syndrome

• Associated w/ extremely

heavily muscled hogs

• May result in sudden

death

• Failure of circulatory

system

• Unable to withstand

stress of normal

management:

– Handling

– Crowding

– Transporting

– Sudden changed in

environment

x P p

p Pp pp

p Pp pp

Pp = 50% carriers of the PSS condition, but do not exhibit symptoms.

pp = 50% carriers of the disease that do exhibit the symptoms.

PSS • Genetic condition that is carried & transmitted

by a recessive gene.

• If a heterozygous boar (Pp) is mated to a

homozygous gilt with Porcine Stress

Syndrome (pp – recessive), the probability of

offspring having PSS is 50%

Solve the Problem

• Porcine Stress Syndrome: A homozygous

recessive (pp) Yorkshire boar is crossed with a

homozygous dominant (PP) Yorkshire Gilt.

What is the percentage of the offspring will be

carriers of PSS, will show signs of PSS, and

those that will not have PSS?

Solve the Problem

• Porcine Stress Syndrome: A heterozygous (Pp)

Yorkshire boar is crossed with a homozygous

dominant (PP) Yorkshire Gilt. What is the

percentage of the offspring will be carriers of

PSS, will show signs of PSS, and those that

will not have PSS?

Solve the Problem



heterozygous (Pp) Yorkshire Gilt. What is the

percentage of the offspring will be carriers of

PSS, will show signs of PSS, and those that

will not have PSS?

Solve the Problem



homozygous recessive (pp) Yorkshire Gilt.

What is the percentage of the offspring will be

carriers of PSS, will show signs of PSS, and

those that will not have PSS?

Indications of PSS

• Abnormal nervousness

• Constant movement

• Tail switching

• Muscle tremors

• Trembling ears

• Red blotches on white hogs when excited

• Purple blotched on black hogs when excited

• Elevated body temperature

PSS

• Produces unacceptable quality meat

– PSE = Pale, Soft, & Exudative (watery)

– DFD = Dark, Firm, & Dry

• Either type is unacceptable!

• Should be culled from the herd

– Taken out

Breed Character

• Breed standards

• Color, shape of head, & ear shape

• Breeder’s preference

Photo from IMS.


Photo from IMS.

Performance Data

• Actual record of individual animal

– Reproductive

– Productive

– Carcass traits

Sow Productivity

• # born alive

• Number @ 21 days

• Litter birth weight

Performance Ability

• Growth rate

• Feed efficiency

Carcass Traits

• Backfat

• Loin Eye Area

• Percent lean

Lean cuts

Performance Data

• Emphasis what you want for your production

system

3 Degrees of

Muscling:

Superior (thick)

Average

& Inferior (thin)

Pedigree

• Record of animal’s ancestry

• Carries impressive production records

– Lends confidence when projecting how well young

animals will perform

• Names & registration numbers are

meaningless unless the superior individuals &

outstanding producers are close in lineage.

Expected Progeny Differences

EPDs • Estimates of expected performance of an

animal’s offspring (progeny)

• Most accurate means of selection

– Takes into account the individual’s performance,

– Parents’ & siblings’ performances, and

– Progeny performance

EPDs

• Calculated for 4 main traits:

– # pigs born alive (NBA)

– 21-day litter weight (LWT)

– Adjusted backfat (BF)

– Days to reach 250lbs (DAYS)

EPDs

• Expressed either as a + different or - difference

from population average

• Positive # is favorable for NBA & LWT

• Negative # is favorable for DAYS & BF

Boar

Number

DAYS

(lb.)

BF (in.) LWT

(lb.)

NBA

1 -1.4 -0.01 +1.5 0.00

2 +2.3 +0.03 -3.7 -0.60

3 -1.5 -0.03 +1.7 +0.15

4 -1.1 +0.02 +3.9 +0.60

EPDs of Yorkshire Boars

Gilt

Number

Days to

250 (lb.)

Adjusted

Backfat

(in.)

Adjusted

LEA*

(in2)

Dam’s

SPI**

1 168 0.60 6.4 108

2 165 0.65 6.2 104

3 178 1.00 4.6 99

4 169 1.33 5.5 98

* LEA = Loin Eye Area (in square inches); ** SPI = Sow Productivity Index

EPDs of Duroc Gilts

ALL RIGHTS RESERVED

Reproduction or redistribution of all, or part, of this presentation without written permission is prohibited.

Instructional Materials Service

Texas A&M University 2588 TAMUS

College Station, Texas 77843-2588

http://www-ims.tamu.edu

2007

http://www-ims.tamu.edu/



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