Pig Slaughter Lab

 Industry Scale + Market Hog Basics

• Slaughters about 12,500 hogs/day
   

• Ideal market hog:

  • Lean, muscular

  • 5–6 months old

230–260 lb liveweight

Criteria for a “Good” Slaughter Method (same principles as beef)

1. No cruelty

2. Minimize stress

3. Fast, complete bleeding (exsanguination)

4. Minimal carcass damage

5. Must be:

   • Hygienic

   • Economical

   • Safe for workers

The 8 Major Steps (Red Meat Species)

1. Ante-mortem inspection

2. Stunning

3. Exsanguination (bleeding/sticking)

4. “Skinning” step (for pigs = usually dehairing, skin stays)

5. Evisceration

6. Post-mortem inspection

7. Final carcass prep

8. Chilling

1) 🧼 Biosecurity + On-Farm Loading (Temple Grandin)

• Truck drivers wear coveralls / stay outside barn

• Avoid bringing disease into barns

• Important idea: visit farm first, then plant (plant has pigs from many sources → don’t bring plant germs to farm)

Loading pigs (handling principles)

• Use calm driving tools:

  • Sort board

  • Rattle

  • Paddle

  • Flag (acts like a light “solid barrier”)

• Move small groups (too many → pile-ups/injury)

• Pigs are curious—often follow and load more easily when calm

• Trailer ventilation is adjusted with side panels/boards:

  • Cold weather: more boards but still must allow ventilation

  • Hot weather: fewer/removed boards for airflow

2) 🚚 Unloading at the Plant (Temple Grandin + Lab Welfare Standards)

Correct unloading setup

• Truck must be perfectly aligned with dock so pigs don’t step into a gap and injure legs

• Non-slip flooring is essential (scored concrete; shavings may be used)

Audit benchmark (Temple Grandin)

• If >1% of pigs fall down during unloading/handling → something is wrong (flooring/handling) and must be corrected

Visual barriers

• Solid barriers used so pigs don’t see people and get scared/agitated

• Example: barrier made higher with boards so pigs can’t see heads above it

3) 🏷 Identification / Traceability

Why pigs use tattoos (not ear tags)

• Ear tags can be ripped off later by the dehairing machine

• So pigs are given a slap tattoo that remains visible after hair removal

• Traceability = can track pig back to farm/load origin

4) 🧑‍⚕ Ante-Mortem Inspection (Before Death)

• Same core idea as beef: ensure animals are fit for slaughter & food safety

• Pigs are typically rested 1–4 hours after unloading before slaughter

• USDA vet/inspector checks pigs:

  • At rest + in motion

Disease signs, elevated temp, lameness, abnormalities

Excel plant sorting rules (important):

• Sort out abnormal hogs, boars/sows, small hogs

• Excel slaughters barrows and gilts (not boars/sows)

• Downed hogs: inspected; if passed → may go to slaughter

• Dead hogs → rendering

5) 🧘 Resting in Holding Pens (Lairage for pigs)

Temple Grandin

• Minimum rest: 1 hour

• Preferably: 2–4 hours

• Helps pigs calm down and cool off

• Reduces risk of PSE meat (Pale, Soft, Exudative) especially in heat

Excel transcript holding pens

• Avoid overcrowding + injury

• Pens have few right angles → reduces bruising and carcass value loss

• Feed withheld; water provided

• Misting water:

  • cools pigs

  • helps wash off dirt

• Holding barns:

  • insulated, heated in winter

  • fans in summer

Pen layout (Temple Grandin)

• Herringbone layout: pigs enter one end, exit the other → one-way flow improves movement/traffic

6) ⚡ Stunning (Major pig vs beef difference)

Allowed/used methods

• Captive bolt: limited to mature breeding stock (sows/boars)

• Electrical stunning (common in some systems; used in Excel video)

• CO₂ stunning (common in large Ontario plants; shown in Grandin video)

CO₂ Stunning (Temple Grandin explanation)

• Pigs walk into a gondola (combi)

  • ~5–6 pigs per gondola

• Door closes; gondola lowers ~30 feet into a pit to ~90% CO₂

• Pigs become unconscious (must reach surgical anesthesia/insensible)

• Come out loose/floppy

• Powered gates must never drag pigs (proximity switch control; dragging is against humane rules)

CO₂ design note (lab notes):

• CO₂ is heavier than air → trapped in pit/tunnel

• Usually 65–90% CO₂

• Pigs unconscious after about 1–3 minutes, then must be bled rapidly

• Modern CO₂ systems use sensors to control gas levels accurately; older systems were less controlled

Electrical Stunning

How it works (Excel slaughter)

• Pigs go single-file into conveyor restrainer

• Stunning device has two probes:

  • one behind left ear

  • other on opposite side of body

• Held ~2 seconds

• Current applied: 250–350 volts at 1.4 amps

• Stunning does not kill—renders unconscious

Key welfare point (Grandin)

• After electrical stunning you often see:

  • lots of kicking

  • grand mal epileptic seizure

• This is expected in properly stunned animals

• Electrical stunning must send current through the brain:

  • wrong placement could stop heart but pig could still feel pain (very serious welfare failure)

Lab note cautions (electrical stunning)

• Electrodes must be clean for good contact

• Some systems send current through chest to stop heart (may restart later)

• Head-to-back high voltage may cause:

  • vertebral fractures

  • blood splashes

• High-frequency stunning may reduce carcass damage

7) 🔪 Exsanguination (Bleeding / Sticking)

General principles (lab notes)

• Must be done correctly; bad placement causes slow bleeding + clotting
  Possible problems if done wrong:

• Too slow; bleeding may halt due to clots

• Trachea cut → blood drawn into lungs → later trimming needed

• Esophagus cut → food particles contaminate vascular system

• Shoulder connective tissue opened → blood clots between muscles

• Incomplete bleeding → dark lean, blood-streaked fat

Excel specifics

• After stunning, shackle placed on rear leg → moved to sticking line

• Anti-coagulant sprayed into blood trough so blood doesn’t clot before processing

• Sticking method:

  • insert 6-inch sticking knife between sternum and backbone

  • upward thrust, then dip point until it strikes backbone

  • severs carotid artery + jugular veins

• Blood loss: about 8 lb = ~3.5% of a 230 lb hog

Travel time from sticking to scald tubs: ~6.5 minutes (allows complete bleeding)

8) 🧼 “Skinning” Step for Pigs = Dehairing (Major difference vs beef)

Most plants leave the skin on and remove hair; skin is often removed later during butchering and used for food-grade gelatin

Dehairing sequence

1. Scalding

   • Hot water loosens hair follicles

   • Excel: scald tubs at 140°F

   • Takes ~6.5 minutes to travel through tubs

2. Dehairing machine

   • Tumbling + paddles/cleats + hot water removes hair (and toenails)

   • Bruising is minimal because little blood remains in muscles after bleeding

3. Gambrel attachment

   • Cuts in hind feet expose tendons → attach gambrel, move to dressing rail

4. Singeing (Singer)

   • Flame chamber burns remaining hair

   • Also improves food safety by reducing surface pathogens (Grandin notes this benefit)

   • Remaining hair may be manually shaved

Lab note: singeing can be torch/manual or automated machine

9) 🧠 Additional Carcass Prep Steps (Excel details)

• Toe jamming: remove webbing/hair between front toes (front feet used for human consumption; back feet to rendering)

• Hair/skin around eyes and eyelids removed

• Neck hair trimmed (hand skinner)

• Stick wound trimmed of clots/excess skin

10) 🧾 Head Handling + Inspection (pig-specific detail)

• Head is partially dropped:

  • uses a neck breaker through atlas joint, esophagus, trachea

  • sanitized in 180°F water after each hog

  • Knife is used to complete process small strip of skin keeps head on

• Care not to cut mandibular lymph nodes (must be inspected)

• “Suspect” carcasses tagged/pulled for further inspection

11) 🫁 Evisceration (Remove organs)

Definition: removal of internal organs.

Key pig suspension difference:

• Beef: hook through Achilles tendon

• Pig: gambrel suspends carcass

Steps (Excel process)

• Brisket saw splits sternum (sanitized in 180°F after each hog)

• Abdominal wall opened carefully (don’t puncture intestines)

• Aitch bone split with power shears (prep for splitting)

• Bunging loosens anus + reproductive tract

• Viscera removed and placed on a tray that follows carcass:

  • Viscera = intestines, liver, stomach

  • Pluck = heart + lungs

• USDA inspector checks tray; abnormal → retain area

Lab notes (general rule)

• Viscera removed posterior → anterior

• Remove diaphragm, then plucks (trachea, heart, lungs)

12) 🔍 Post-Mortem Inspection (After death)

Lab notes pig-specific:

• Head: inspect submaxillary lymph nodes

• Viscera: inspect major organs + lymph nodes

• Carcass: check abscesses

Outcomes:

1. Hold for testing (may trim or condemn specific organs)

2. Condemn carcass/organs → destroy/render

3. Pass into human food chain

13) ✂ Splitting + Trimming + Leaf Fat (Excel)

• Kidneys exposed

• Split down backbone with back saw (sanitized 180°F after each carcass)

• Proper cut leaves “feather bones” on each side of loin

• Carcass not fully separated into two sides until fabrication (prevents slipping off gambrel)

• Re-work trimming line removes remaining membranes

• Leaf fat (kidney fat equivalent) removed from each side

14) 📏 Lean % Measurement + Payment (Excel)

• Tool: Fat-O-Meat’er

• Measures backfat (mm):

  • plunger inserted between 3rd–4th ribs, ~1.5–2 inches from spine

• Carcass weighed on rail; computer calculates % lean

• Typical Excel hog: 51–52% lean

• If carcass meets lean:weight ratio → marked for export

Lab note: Canada uses similar tech but not Fat-O-Meat’er specifically

15) 🚿 Final Wash + Chilling (Major plant differences)

• Pork can chill like beef, but usually fabricated next day

• Cold shortening is less of a problem because skin + subcutaneous fat slow cooling

• Some plants use blast chilling:

  • -40°C for up to 1.5 hours

  • improves lean color

  • helps prevent PSE

Excel chilling details:

• Blast tunnel at -40°F

• Carcasses remain ~1.5 hours (not fully frozen)

• Then holding coolers at 36°F for 12–20 hours until fabrication ready

Temple Grandin:

• Holding cooler before cutting: typically 24–48 hours (general plant statement)

HACCP

• Hazard Analysis and Critical Control Points

• Identifies where hazards might occur and controls them

Critical control points mentioned (Excel)

• Singer (singeing step) is described as a critical control point

• Trimming/rework lines also treated as control points

• Final wash is last control point before chilling

Cleaning + inspections

• Production areas cleaned/sanitized daily

• Pre-operational inspection before first shift by USDA + plant staff

• If problems → re-clean, re-sanitize, re-inspect

• Gambrels/trolleys sanitized before reuse

PPE / worker safety (Grandin)

• Hairnets

• Belly guard

• Chain-mail sleeve + cut guards

• Cut-proof gloves

• Hard hats

• Nightly conveyor teardown + wash (not weekly)

17) ♻ Byproducts / Offal (Nothing wasted)

Term:

• Offal = non-carcass parts remaining after slaughter

Blood utilization (Excel)

• Pumped to blood room

• Separated by centrifuge into:

  • red cells

  • plasma/serum

  • white cells
    
    Uses:

• adhesives, fertilizer

• pharmaceuticals/medical products

• cosmetics, animal feeds, dyes

Hair/toenails

• Used as protein in animal feeds

• Also in filters, brushes, upholstery

Edible byproducts (Excel + lab notes)

• Liver (packaged)

• Heart

• Tongue

• Kidneys

• Tail

• Feet

• Head

• Cheek meat

• Brain (boxed/sold)

• Pork skin → edible crisp product; also leather good

Inedible rendering (Excel)

• Ground → cooked at 270°F for ~2 hours

• Grease rises (inedible grease shipped in tank cars)

• Solids → pressed/extruded → meat and bone meal for animal feed

18) 🐷 Definition of a Pig/Hog Carcass (BIG EXAM DIFFERENCE)

Pig/Hog carcass (definition)

• Carcass = entire body excluding internal organs, except kidneys

• Included in hot carcass weight (pig):

  • head

  • feet

  • leaf-lard

  • kidneys

  • tail
    (removed only after hot carcass weight is known)

Compare to beef (important contrast)

• In beef, head/feet/tail/kidneys etc. are NOT part of carcass definition/hot carcass weight (you need to know this difference)

19) 🧮 Dressing Percentage (Pig)

• Pig typical dressing %: 75–80%
  Example:

• 120 kg live gilt → 96 kg carcass

• Dressing % = (96 ÷ 120) × 100 = 80%

• Carcass yield = carcass wt ÷ live wt
  (example given: 195 lb carcass / 260 lb live = 75%)

20) 🧭 Animal Welfare Auditing (Temple Grandin – pork specific)

Audits monitor:

• % falling/slipping (frequent falls = flooring/handling issue)

• Vocalization (pigs squeal more than cattle, but excessive squealing suggests problems like pinching or prod use)

• Insensibility checks (no return to consciousness)

• Electrical stunning placement (must send current through brain)