The Animal Welfare Science Centre Evaluation of sow stall dimensions John Barnett Animal Welfare...

The Animal WelfareScience Centre

Evaluation of sow stall dimensions

John Barnett

Animal Welfare Science Centre, Department of Primary Industries, Werribee


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Stall housing is a controversial welfare issue for the pork industry

Criticisms of individual (stall) housing of sows

– sows unable to exercise

– limited social contact between sows

– restriction of “naturalistic” behaviours

eg. dunging vs lying vs feeding area

40-60%(?) of gestating sows in Australia are stall housed

~26%(?) of Australian sows are stall housed for 15 weeks / parity

– concern over long-term individual housing (15 weeks) in stalls then crates

Code of Practice (welfare) defines minimum stall dimensions:

– stall width = 0.6 m

– stall length = 2.0 m (“clear space”: excludes feeder and water facilities)

Background


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Stalls banned in some countries

– Sweden, Norway(?), Finland (2006), Switzerland (2007), Netherlands (2008), Denmark (2014)

Restricted time in stalls

– European Union - maximum of 4 weeks post-mating from 2013

– New Zealand - (recommendation only at this stage) maximum of 6 weeks post-mating from 2009 and 4 weeks post-mating from 2013 (to be reviewed in 2009) (new stalls max of 4 weeks post-mating)

Overseas recommendations on stalls


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Cortisol concentrations in 4 housing treatments (nmol)

StallsVertical

4.4a

StallsHorizontal

6.6b

Tether

6.6b

Group

4.4b

From Barnett et al., 1991b


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To determine:

1) the effects of stall dimensions on the welfare of sows

2) if there is a minimum time in stalls that results in improved reproduction without compromising sow welfare

Objectives of Project


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Evaluate the effects of:1) Sow stall dimensions on welfare

2) Time in sow stalls on reproduction and welfare - commercial facility

3) Sow stall length and time in stalls on reproduction and welfare - commercial facility

Student project:4) Effects of housing in stalls and implications for forming

social relationships

Experiments to:


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2 years 4 replicates in time 7 treatments (3 x 2 factorial) plus external, negative control Factors examined:

Stall length (2.0 m vs 2.2 m vs 2.4 m) Stall width (0.6 m vs 0.75 m)

External, negative control = tether stalls Positions of treatments (banks of stalls) randomised

between reps 4 sows per bank of stalls

2 non-experimental and 2 experimental sows 56 experimental & 56 non-experimental sows parities 2-6

Experiment 1 - Sow Stall Dimensions


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Conventional width stall (0.6 m wide)

Wide stall (0.75 m wide)

Stall width


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Stall length

2.0, 2.2 and 2.4 m long in banks of 4


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(0.6 m wide)

Tether stall - control


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Measurements

1) Sow physiologySurgery to implant catheter in cephalic vein• at ~8 weeks into treatment• day-time profile of plasma cortisol concentrations• cortisol response to ACTH injection• cell-mediated immune response

2) Sow lameness and live weight• measured at entry and exit from treatments


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Measurements

3) Sow behaviour post-feeding & “at rest”• Video recording at ~7 weeks after entry to stalls

– level of activity– social behaviour

• aggression• affiliative behaviour (lying together vs apart)

– angle of turn in stalls


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Results - cortisol concentrations

Width of stall Length of stall Tether0.6 m 0.75 m 2.0 m 2.2 m 2.4 m

Total cortisol conc. nMol 18.4p 25.5q 22.5 20.8 22.6 36.6

Free cortisol conc. nMol 2.3x 3.0y 2.7b 2.3a 2.9b 3.5

a,b: P<0.05; x,y: P<0.01; p,q: P<0.001

Free cortisol concentrations were lower in the 0.6 m wide stall & the 2.2 m long stall


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Results - response to ACTH


Total cortisol conc. 18.4p 25.5q 22.5 20.8 22.6 26.1pre-ACTH nMol

Total cortisol conc. 2.80a 3.02b 2.95q 2.76p 3.02q 3.13post-ACTH % increase(log value)

a,b: P<0.05; p,q: P<0.001

In a chronic stress response the response to ACTH is increasedThere was a lower response to ACTH in the 0.6 m wide stall and the 2.2 m long stall


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Results - cell mediated immunity

Width of stall Length of stall Tether 0.6 m 0.75 m 2.0 m 2.2 m 2.4 m

Cell mediated immunity 108.4b 91.2a 91.1pq 119.1q 89.1p 81.7(% increase in skin thickness)

a,b: P<0.05; p,q: P<0.001

The greater the % response the “better” the animal’s immune system (higher response in 0.6 m wide stall and 2.2 m(?) long stall)


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Results - Behaviour

Activity Post-feeding observations:• sows in 0.75 m wide stalls were

• more active (86% vs 74% of time; P<0.05); and• took longer to lie down (101 min vs 86 min)

No effects of treatment on aggression


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Results - Affiliative behaviour (forward index)

Index score of the preference of sows to occupy the same spatial alignment as their neighbours during the 2-h observation

period ie. heads of neighbours at the front of the stall Width of stall Length of stall

Observation period 0.6 m 0.75 m 2.0 m 2.2 m 2.4 m

Post-feeding -0.04 -0.23 -0.16 -0.35 +0.11

Afternoon -0.53 -0.47 -0.39 -0.80 -0.31

• A negative index indicates that neighbouring sows were separated.• A positive score indicates that neighbouring sows were together.• A score close to zero implies the spatial alignment between neighbouring sows was random.

Sows were generally lying apart (ie. lack of head to head contact)


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Results - Angle of turn (post-feeding)


Mean turn angle° 38p 50q 48b 42a 41a 36

Mean maximum angle° 47x 59y 61y 50x 49x 44a,b: P<0.05; x,y: P<0.01; p,q: P<0.001

Conventional stall width (0.6 m)

Wide stall width (0.75 m)

Angle of turn greater in 0.75 m wide stall and 2.0 m long stall


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Summary - Physiology

• Welfare improved in: • 0.6 m wide compared to 0.75 m wide stalls

• based on lower total and free cortisol concentrations• reduced responsiveness to ACTH• increased immunoresponsiveness

• 2.2 m long stalls compared to 2.0 m long stalls• based on lower free cortisol concentrations• reduced responsiveness to ACTH•increased immunoresponsiveness (vs. 2.4 but not 2.0 m long stalls)


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Summary - Behaviour

• Behaviour data inconclusive:• No effect on social behaviour?

• wider stalls allowed sows to turn more• 2.4 m long stalls allowed more movement• how are these social behaviours perceived? eg threatening

• Affiliative behaviour• generally negative scores• indicates sows preferred to be apart at front of stall


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Experimental study on stall dimensions

– stall divisions were horizontal bars

– no positive control treatment

Constraints


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Stall Width– improved welfare with a stall width of

0.6 m stall Length

– improved welfare with a stall length of

2.2 m

Overall conclusions

It is the design of the system rather than the housing system per se that is important to welfare


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A collaborative project between:

Animal Welfare Science Centre / Department of Primary Industries

Australian Pork Limited

Thanks to:

co-researchers: Greg Cronin, Paul Hemsworth

technical staff: Lisa Newman, Samantha Borg, Bruce Schirmer

and

AWSC students at DPI Werribee

Thanks

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