title: Omnivores Going Astray: A Review and New Synthesis of Abnormal Behavior in Pigs and Laying Hens.
abstract: Pigs and poultry are by far the most omnivorous of the domesticated farm animals and it is in their nature to be highly explorative. In the barren production environments, this motivation to explore can be expressed as abnormal oral manipulation directed toward pen mates. Tail biting (TB) in pigs and feather pecking (FP) in laying hens are examples of unwanted behaviors that are detrimental to the welfare of the animals. The aim of this review is to draw these two seemingly similar abnormalities together in a common framework, in order to seek underlying mechanisms and principles. Both TB and FP are affected by the physical and social environment, but not all individuals in a group express these behaviors and individual genetic and neurobiological characteristics play an important role. By synthesizing what is known about environmental and individual influences, we suggest a novel possible mechanism, common for pigs and poultry, involving the brain-gut-microbiota axis.
authors: NORSØK - Norwegian Centre for Organic Agriculture, Tingvoll, Norway; NIBIO - Norwegian Institute for Bioeconomy Research, Tingvoll, Norway.
authors: Emma I
authors: EI
authors: Brunberg
authors: Behavioural Ecology Group, Wageningen University , Wageningen , Netherlands.
authors: T Bas
authors: TB
authors: Rodenburg
authors: Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences , Uppsala , Sweden.
authors: Lotta
authors: L
authors: Rydhmer
authors: Federal Research Institute for Animal Health, Friedrich-Loeffler-Institut , Celle , Germany.
authors: Joergen B
authors: JB
authors: Kjaer
authors: AVIAN Behaviour Genomics and Physiology Group, IFM Biology, Linköping University , Linköping , Sweden.
authors: Per
authors: P
authors: Jensen
authors: Department of Animal Environment and Health, Swedish University of Agricultural Sciences , Uppsala , Sweden.
authors: Linda J
authors: LJ
authors: Keeling
keywords: animal welfare; feather pecking; gut–brain–microbiota axis; poultry; swine; tail biting