Depopulation, transport, and stunning

What is the general industry standard when raising broiler chickens?

All in all out, controlled environments

What are the management methods for laying hens commercially?

Enriched cages, barn, and free range

What genetic problems are inherent in commercial broiler chickens?

Leg problems

What genetic problems are inherent in laying hens commercially?

Osteoporosis

A consequence of the large populations in chicken production is that individuals

Have low value and productions have tight profit margins

Who typically catches the chickens and when does this occur to send them for harvesting?

Contracted catching crews catch at night

What should be done prior to chicken harvesting?

Food and water withdrawn in advance (6-12h)

What are common consequences to broiler harvesting?

Injuries including bruising, fractures, and dislocations

Also identified as major source of stress and injury

What is NOT permitted when harvesting broiler chickens?

Manually catching, lifting, and carrying chickens by one leg

What are advantages of Mechanized harvesting?

reduced labor costs, better conditions for workers, reduced rejection rates, reduced injury and bruising, especially leg injury rates - welfare benefits?

What are the disadvantages of mechanized harvesting?

speed of catching slower, structural difficulties

What is the current way lay hens are depopulated?

caught all by hand, long carry distances (catcher → carrier → loader

What are the current issues with lay hen depopulation?

considered low or no value (no incentive for careful handling), many injuries (more in cage during depopulation, more in barn/free range are old fractures)

What is the difference in transport of broilers and laying hens?

increased mortality in laying hens

Where do laying hens in Scotland have to go to be slaughtered?

England

How does thermal stress happen in passively ventilated transporters?

heterogeneous distribution of ventilation causes hot and cold spots

some birds experience cold stress while others experience heat caused by localized high air velocities

What does high stocky density cause during tranport?

thermal stress (compromised ability to thermoregulate by natural means)

What are broilers particularly susceptible to during transport?

heat stress and dehydration

Why are broilers so susceptible to heat during transport?

genetic selection for muscle growth has compromised capacity to response to acute thermal challenge

How are thermal comfort zones defined?

based on thermal load (temperature + humidity)

In relation to thermal comfort zones - What is #1?

Safe

In relation to thermal comfort zones - What is #2?

Alert

In relation to thermal comfort zones - What is #3?

Danger

Day Old Chick transport optimum temperature is?

24-25 C and 60% RH

Can day old chicks tolerate long journeys?

yes - yolk sac reserves

How do pullets compare to chickens or spent hens during transport?

withstand greater excursions in ambient thermal conditions

What must you consider when transporting end of lay hens?

poor feathering (reduced thermal tolerance)

excessively vulnerable to cold and wet conditions (comfort zone 22-28C)

heat stress in some parts of vehicle

Longer journey times

Higher DOA rates

thermoregulatory ability compromised

Why are end of lay hens thermoregulatory abilities comprimised?

physiological fatigue and prolonged pretranport food withdrawal

Why do some lairages result in increased stress on broiler chickens?

Holding time may exceed journey time, seasonal temperature variations, poor ventilation in stacked crates

What can some lairages do to reduce stress in the birds?

Subdued or blue lighting

What is the main factor influencing DOA rates in chickens?

Ambient temperature

Other than the main factor influencing DOA rates in chickens, what can contribute to these rates?

Catching company, breed, flock size, mean bodyweight, mean compartment stocking denisty, transport time, and lairage time

What is the ante mortem inspection of chickens used to verify?

Animal identification, animal welfare, and any condition that may adversely affect human or animal health

Overall health and welfare of each load must be assessed

What are signs of disease in poultry?

Swelling around the head and eyes, edema of the wattles, gasping and sneezing, off colored diarrhea, skin lesions, obvious lameness, abnormal neck posture, bone or joint enlargement

What are acceptable stunning methods for poultry slaughter?

Electrical and gas

Requirements for humane slaughter for chicken include

duration of stun should be longer than time to death from blood loss and stunning methods are only acceptable when they result in minimal signs of agitation and distress before loss of consciousness

Stimulation of the brain with electric current of sufficient magnitude leads to what?

Generalized epilepsy

What method of stunning is described with the following:

Most common approach, current flows through the birds in the shackle line, minimum current applied to each bird varies widely, ideally casues instantaneous loss of consciousness.

Water bath stunning

What are the basic requirements of water bath stunning?

Water bath supplied with a voltage sufficient to ensure that eveery bird receives the recommended minimum current

Electrode in water bath must extend the length of the abth

Good contact between legs of the birds and the shackle line

Birds must be completely immersed

Water should not overflow the enterance to the bath

From a welfare perspective, we want a __ frequency and a __ current

The meat quality/sellers want the opposite

Low, high

What are some welfare issues with electrical stunning?

Requires shackling of a live bird, some are not adequately stunned, pre stun shocks are common

What method is described with the following:

Enter via crates or a conveyer, no need for live shackling

All birds stunned (non-recovery)

Shackled post stun, improved meat quality, improved working conditions at shackling point

Controlled atmosphere (gas) stunning

When performing controlled atmosphere stunning, we can use what gases?

Inert gases, high concentration CO2, CO2 and inert gases, or multiphase gases

What is the process outlined in multiphase controlled atmosphere stunning?

Anesthetic phase CO2, higher concentration once birds have lost consciousness (sub nociceptive concentrations before loss of consciousness)

What potential welfare issues arise with controlled atmospheric stunning?

Initial aversion, respiratory effects (air hunger/difficulty breathing), and behavioral effects (convulsions, injuries from flapping)

What are some potential welfare advantages to low atmospheric pressure stunning?

No live shackling, all birds stunned

What are some welfare concerns with low atmospheric pressure stunning?

Air hunger, pain caused by expansion of air in resp, alimentary tracts and sinuses of the skill, teeth, and middle ear

How can we emergency kill chickens? (ex if avian influenza concerns etc)

Containerized gassing units or whole house gassing

How do we kill chickens in containerized gassing units?

80% argon and 20% CO2, fill in about 2 minutes and leave full for 30 seconds to effectively kill birds.

How do we kill poultry with whole house gassing?

Vents sealed, ventilation turned off. All eprsonnel cleared, gas application (liquid CO2) through single or multiple lances

CO2 must reach 45% at roof sensor (can take up to 30 min)

What welfare considerations do we have for whole house gas killing?

Reliable exposure, all birds killed

Gradual induction of unconsciousness

Do NOT experience high concentrations of CO2 while conscious

What are strengths of emergency whole house gassing?

Widely used proven technique, live birds do NOT need to be handled, large numbers can be killed quickly, humane

What are weaknesses of emergency whole house gassing?

Need technical support, H&S associated with use of gas, large quantity of gas required, limited range of suitable houses

How does high expansion foam work?

Delivers N2 bubbles, birds pop bubbles and the gas forms an anoxic environment. Delivery can have antivirals added to it as well and can be applied to a wide range of systems