Card Set Information

2010-11-28 10:10:03
Animal Husbandry

Poultry Welfare
Show Answers:

  1. Issues
    • Large numbers of Individuals (860 million broilers + breedrs) and 30 million laying hens
    • genetic selection= inherent problems
    • low individual value= less care/vigilance per animal, financial implications
    • limited public awareness/concern
  2. Laying hen problems
    • feather pecking and cannibalism
    • bone fracture
  3. broiler problems
    • food restriction in breeders
    • broiler welfare- media and public response
  4. Feather pecking
    • def: damaging bird to bird pecking observed in laying hens, turkeys, pheasants, quail and ducks
    • reports as early as 1930's
    • major welfare and economic problem in the egg industry
    • highly unpredictable (half of britis producers suffered outbreaks in their last flock)
  5. Feather pecking is NON-aggressive!
    • vigourous or gental pecks:
    • deliberate, repeated persistently, aimed at any part of body, recipient may withdraw, only vigourous pecks damaging
    • gentle pecks more common
    • allopreening?- birds being feather pecked do not resist or object
    • feather pulls:
    • removed feathers eaten, bare skin pathes result
    • evidence for pain when feathers are removed
    • reduced insulation- increased energy requirements
  6. Aggressive pecking
    • maintenance of dominance hierarchy (different motivation)
    • rarer than non-aggressive pecks (overt, rapid, forceful, rarely repeated, aimed at head or neck, recipient withdraws, damaging)
    • relationship between dominance and feather pecking unclear
    • confusingly, industry uses term "agression" for feather pecking
  7. Cannibalism
    • tissue pecking aimed at skin, preen gland, or vent and underlying tissues
    • correlated w/ severe feather pecking (non-aggressive)
    • usually results in death (mortality up to 30% intact beak flocks)
    • unpredictable
    • may be triggered by accidental injury or bleeding feathers
    • vent pecking associated w/ onset of lay?
    • nutrient deficit? (protein level, source?, specific nutrients?)
  8. Beak trimming ('debeaking')
    • removes part of upper beak (hot blade, infra red methods)
    • causes acute pain (beak guarding)
    • reduces effectiveness of beak (changes beak shape, loss of senosry feedback, beak used less forcefully (chronic pain?))
    • majority of layer flocks beak trimmed
    • (organic and rare breeds are not!)
  9. Why do chickens feather peck?
    • not fully understood despite 50 years of research- unpredictability a problem
    • scientific research- commercial egg production (massive differences in scale)
    • mulifactorial (external factors- environmental), (internal factos-independent or environment)
  10. Causation: external factors (feather picking)
    • light:
    • damaging pecking increases w/ increasing light intensity- probably acts by increasing activity levels
    • light wavelength/type also affects incidence
    • floor substrate:
    • evidence that feather pecking/cannibalism is redirected ground pecking/foraging
    • (less feather pecking when foraging increases, fewer pecking problems when pecking substrate is provided)
    • Stocking density/group size:
    • evidence for size-stocking density interaction- group size affects number of peckers and potential victims
    • individual recognition in large groups- breakdown of dominance hierarchy
    • diet:
    • studies have implicated dietary fibre, various aa, sodium, protein level
    • food form effect- more pecking w/ pellets than w/ mash- layer flocks routinely fed mash
    • food delivery- scatter feeding encourages foraging
    • environmental enrichment- various objects and "toys" have been tested as anti-pecking devices
    • limited evidence that EE reduces damaging pecking
    • production system:
    • various environmental factors acting together
    • increased pecking problems w/ extensive systems (large group sizes, high stocking density, few peckers can inflich much damage)
    • cages contain pecking problems- peckers have access to fewer birds
  11. Causation: internal factors
    • genetic variation:
    • obvious strain differences in incidence and extent of pecking damage
    • individual variation: peckers and non-peckers
    • some behavioural correlates demonstrated (peckers more active, peckees preen more, peckers foage less)
    • cant' we select for non-peckers?
    • co-selection w/ increased egg production- high egg number early onset of lay
    • easier to select for pecking than against it
    • limited success
  12. Current situation (legal)
    • EU conentional cage ban in 2012
    • enriched cages permitted (studies ongoing to examine effects on incidence of feather pecking)
    • will laying hen welfare be improved? (directive will encourage the use of non-cage systems, pecking and dz problems likely to worsen)
  13. Bone biology in laying hens
    • bone types:
    • cortical bone, trabecular bone, medullary bone
    • mineral supply function (calcium)
    • supports egg shell production
    • wild-birds- season formation of medullary bone
    • laying hens:
    • selection for early egg production and high egg yield
    • sustained egg production (all year- uses all medullary bone)
    • progressive loss of structural bone leading to fragility (osteoporosis)
    • switch to medullary bone producition, inactivity in caged birds
  14. Incidence of Fracture
    • 1) old fractures: occurs during the lifetime of the bird while in the production system
    • 2) new fracture: occurs at depopulation due to handline
    • studes examining old fractures:
    • percher 25%, free range 12%, cage 5% (1990)
    • Perchery 73% (2003)
    • loose housed 50-78% (2004)
    • cage 35% (2004)
    • *most affected bones are keel (90%) and furculum
  15. What causes bone fracture?
    • osteoporosis doesn't account for incidence
    • all laying hens suffer from some degree of osteoporosis
    • more fx in loose systems, especially w/ percehs
    • despite positive effects of exercise on bone strength
    • pressure while sitting on perch?- 59% of body weight borne by keel- cracks
    • collision w/ perches/furniture?- body weight relative to wing area has changed in modern layer strains- reduced flight performance, percehes may be badly positioned- too far apart, steep angles
    • mechanics of flying?- twisting forces on keel in flight?
  16. Current situation (bone fx)
    • bone Fx likely to be painful!
    • no published descritption of pain related behaviour following bone fracture- research needed
    • old breaks most common- chronic pain?
    • hens unlikely to be able to mobilise calsium to properly heal fx- research needed
    • EU conventional cage ban 2012?- wider use of loose housing systems
    • solutions?- rearing w/ perches for practice, selection for flight ability, selection for bone strength
  17. Broiler Production food restriciton
    • Birds reared for meat= 2.5 kg in 42 days
    • selection for: rapid growth, food conversion efficiency, breast meat yield, appetite, inactivity
    • same genetic line
    • (parents) feed intake controlled:
    • slows growth
    • improves health
    • protects fertility
    • saves money
    • birds reach sexual maturity
  18. Food restriction
    • severe- birds get ~30% of ad lib intake during rearing
    • birds cont. hungry: highly active, highly motivated to feed at all times (operant feeding tests showed that motivation to eat is 3 tims greater than that of unrestricted birds subjected to 72 h food deptrivation)
    • exhibit oral stereotypies related to frustration of feeding motivation (spot pecking at non-food objects, polydipsia- over drinking)
    • commercial food restriction contravenes " freedom from hunger and thirst"
  19. how much hunger is acceptable? can we meausre hunger?
    • % of ad lib intake
    • behaviour- food searching, activity
    • plasma glucose/non-esterified fatty acids
    • plasma corticosterone
    • feed of feeding (limited by crop)
    • compensatory feed intake
    • operant techniques (measure motiviaton)
  20. Types of food restriciton
    • quantitative: provide less of high quality food
    • qualitative: provide more food w/ lower energy content (high proportion of indigestible fibre in food)
  21. does qualitative restriction improve welfare?
    • some evidence for benefits (increased satiety, reduced stereotypic behaviour)
    • more difficult to control growth rate
    • feeding motivation and activity level related to growth rate suppresion (regardless of how achieved)
    • qualitative restriction has only limited scope to improve broiler breeder welfare
  22. What else can be done about feed restriction?
    • scatter feeding (increases feeding time- foraging in litter, reduces competition- better weight uniformity)
    • environmental enrichment (encourages non-destructive pecking, reduces drinking and improves litter quality)
  23. Current situation (restricted feed)
    • accepted that food restriction of broiler breeders is a major welfare insult
    • aggree that some degree of restriciton is necessary to preserve health and reproductive fitness
    • feather pecking and cannibalism becoming problematic- beak trimming now utilised
    • use of slower growing birds is the best solution
  24. Broiler welfare issues
    • Celebrity chefs get involved (chicken run, anf jamies fowl dinners)
    • leg disorders leading to lameness (recent survey reported over 27.6% of birds showed poor locomotion and 3.3% were almost unable to walk
    • pain as well as hunger and thirst through lack of mobility
    • cardiovascular problems
    • foot and hock lesions
    • behavioural restrictions (fitness, lameness, high stocking densities, barren environment)
    • hunger in broiler breeders
  25. mechanisms of change
    • consumer driven (media, pricing, ethical views)
    • retailer driven (profit, image)
    • producer driven (quality assurance, image)
    • government driven (legistaltion- including EU)
  26. Do broilers have natural behaviour?
    • release experiemtns suggest that behaviourally, domesticated animals have not lsot the ability or motivation to perform the begavioural repertoire of wild ancestors
    • but are broilers more than just domesticated?
    • body conformational change
    • still chicks at slaughter
    • rapid growth rate associated w/ all other problems
  27. the real welfare issue (rapid growth is associated w/...)
    • cardiovascular problems and poor fitness
    • leg problems
    • foot and hock lesions
    • reduced ability to thermoregulate
    • muscle damage
    • greater hunger in breeders
  28. Free range- solution?
    • more nautral
    • behavioural freedom
    • environmental enrichment
    • slower growth (not possible for broiler)
  29. problems with free range
    • increase dz risk!
    • in large flocks evidence that not all birds go outside
    • outside space may be unsuitable (exposed, cold)
    • increased foot problems
    • parasites
    • hygene
    • predation
  30. intermediate solution???
    • freedom foods:
    • slower growing birds
    • lower stocking density
    • environmental enrichment
    • good dz control
    • lowest incidence of FPD
    • smaller price increase
    • more feasible