Longitudinal effectsof environmental enrichmenton behaviour and physiologyof pigs reared onan intensive-stock farm

摘要

The aim of this paper was to provide a longitudinalevaluation of the effects of physicalenrichments on the behaviour and physiologyof intensive stock-farming pigs. Twenty-eightcrossbred pigs of both sexes, were exposed tofour types of enrichments (hemp ropes, steelchains, plastic balls, rubber hoses) over a periodof eleven weeks. This investigation wasbased on specific abnormal behaviours andphysiological indicators, including hematologicparameters. For behavioural score, focalsampling was used with recording of abnormalbehaviours (body-, tail- and ear-biting), bellynosing, running, and interaction with objects(for Enriched pigs). The presence of skininjuries was also recorded. In general, the frequencyof abnormal behaviours was significantlyreduced in the Enriched group. A timerelatedprofile appeared in the use of theenrichments. Males showed higher occurrenceof skin injuries than females. Physiologicalmeasurements, such as levels of complementsystem, white blood cells and neutrophils, werelower in pigs from the Enriched group. Enriched pigs, as a whole, presented muchlower levels of serum DHEA-S concentrationover two weeks. The findings of this studyshow the successful provision of appropriateenrichments to encourage behaviours whichmay result in satisfactory animal oral interactionwith the enriching objects, preventingthem biting pen-mates. In this respect, theobjects proposed were strongly effective in producingchanges in behaviour which could mitigateinadequate conditions, such as the relationshipbetween animal body weight and theavailable space allowance.