Conferencia magistral

Behavior and welfare of laying hens and broiler chickens

Comportamiento y bienestar en gallinas ponedoras y pollos de engorde

Ruth C Newberry ¹ , BSc, PhD., Ariel M Tarazona , Zoot, MSc, (c)PhD. ²

¹ Center for the Study of Animal Well-being, Department of Animal Sciences and College of Veterinary Medicine, Washington State University, Pullman, Washington, USA.² Universidad Nacional de Colombia, Sede Medellín. FCA/DPA. Centro para la investigación en sistemas sostenibles de producción agropecuaria. CIPAV. Email:rnewberry@wsu.edu

 

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Summary

Although broiler chickens and laying hens belong to the same species, Gallus gallus domesticus, differences in genetic selection pressures, typical housing systems, and age at slaughter result in unique welfare issues (Brunberg et al., 2011, Lay et al., 2011). For example, broiler chickens are at risk of ascites and leg diso rders associated with their rapid growth (Hepworth et al., 2011; Lister et al., 2010), whereas laying hens can be challenged by osteoporosis and cannibalism (Yngvesson et al., 2004). Chicken welfare depends not only on physical health but on psychological health as well. The latter is more difficult to evaluate but vocalizations, behavioral postures, motivational strength, cognitive bias, and self- administration of analgesics can provide indirect measures of psychological welfare (Savory y Hughes 2010, Newberry et al., 2007). One of the most controversial topics requiring attention is acceptable space allowance for poultry (Thogerson et al., 2010). Determining acceptable methods for slaughter (Shields and Raj 2010) and to mass euthanasia of poultry with reportable diseases such as avian influenza is an emerging issue. The purpose of the conference is to outline poultry welfare goals, to identify important welfare issues in broiler chickens and laying hens, and to discuss welfare assessment (Shimmura et al., 2011). Solutions to welfare challenges are addressed, with an emphasis on environmental enrichment (Newberry 1995) and development of welfare assurance programs.

Key words: genetic selection pressure, housing system, poultry, welfare assessment.

 

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Resumen

A pesar que los pollos de engorde y gallinas ponedoras pertenecen a la misma especie (Gallus gallus domesticus), las diferencias en las presiones de selección genética, los sistemas tradicionales de alojamiento, y la edad de sacrificio resultan en problemas de bienestar únicos (Brunberg et al., 2011, Lay et al., 2011). Por ejemplo, los pollos de engorde están en riesgo de ascitis y trastornos de las piernas asociados con su rápido crecimiento (Hepworth et al., 2011; Lister et al., 2010), mientras que las gallinas ponedoras pueden ser afectadas por osteoporosis y canibalismo (Yngvesson et al., 2004). El bienestar de los pollos depende no sólo de la salud física, sino también de la salud psicológica. Esta última es más difícil de evaluar, pero existe evidencia que las vocalizaciones, posturas de comportamiento, la fuerza de motivación, el sesgo cognitivo, y la auto-administración de analgésicos pueden proporcionar medidas indirectas de bienestar psicológico (Savory y Hughes 2010, Newberry et al., 2007). Uno de los temas más controvertidos es el espacio aceptable que requieren las aves de corral (Thogerson et al., 2010). Un tema emergente es la determinación de métodos aceptables de sacrificio (Shields and Raj 2010) y para la eutanasia masiva de aves de corral con enfermedades de declaración obligatoria como la gripe aviar. El propósito de la conferencia es exponer los objetivos de bienestar avícola, para identificar los problemas importantes de bienestar en pollos de engorde y gallinas ponedoras, y para discutir la evaluación del bienestar. Se abordan soluciones a los problemas de bienestar con un énfasis en el enriquecimiento ambiental (Newberry 1995) y el desarrollo de programas de aseguramiento del bienestar.

Palabras clave: aves de corral, evaluación del bienestar, presión de selección genética, sistema de alojamiento.

 

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Referencias

1. Brunberg E, Jensen P, Isaksson A, Keeling L. Feather pecking behavior in laying hens: hypothalamic gene expression in birds performing and receiving pecks. Poult Sci 2011; 90:1145-1152.

2. Hepworth PJ, Nefedov AV, Muchnik IB, Morgan KL. Hock burn: an indicator of broiler flock health. Vet Rec 2011; 19;168:303.

3. Lay DC Jr, Fulton RM, Hester PY, Karcher DM, Kjaer JB, Mench JA, Mullens BA, Newberry RC, Nicol CJ, O’Sullivan NP, Porter RE. Hen welfare in different housing systems. Poult Sci 2011; 90:278-94. Review.

4. Lister S. Leg health in chickens: assessing the assessment. Vet Rec 2011; 22; 168:75-76.

5. Newberry RC. Environmental enrichment: increasing the biological relevance of captive environments. Appl Anim Behav Sci 1995; 44:229-244.

6. Newberry RC, LJ Keeling, I Estevez & Bilčík B. Behaviour when young as a predictor of severe feather pecking in adult laying hens: the redirected foraging hypothesis revisited. Appl Anim Behav Sci 2007; 107:262-274.

7. Shields SJ, Raj AB. A critical review of electrical water-bath stun systems for poultry slaughter and recent developments in alternative technologies. J Appl Anim Welf Sci 2010; 13:281- 299.

8. Shimmura T, Bracke MB, De Mol RM, Hirahara S, Uetake K, Tanaka T Overall welfare assessment of laying hens: comparing science-based, environment-based and animal-based assessments. Anim Sci J 2011; 82:150-160.

9. Thogerson CM, Hester PY, Mench JA, Newberry RC, Okura CM, Pajor EA, Talaty PN, Garner JP. The effect of feeder space allocation on productivity and physiology of Hy-Line W-36 hens housed in conventional cages. Poult Sci 2009; 88:1793- 1799.

10. Yngvesson J, Keeling LJ, Newberry RC. Individual production differences do not explain cannibalistic behaviour in laying hens. Br Poult Sci 2004; 45:453-62.

11. Savory CJ, Hughes BO. Behaviour and welfare. Review. Br Poult Sci 2010; 51 Suppl 1:13-22.