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.
This post illustrates the so-called branched chain design. This is an improved type of chain that seems most suited as a starting point towards providing proper enrichment (as required by e.g. EU legislation) for conventional, intensively-farmed pigs. However, also pigs on straw may benefit from such chains. Below the description of the branched chain design you can find some pictures and video clips of branched, anchor-type chains for pigs (conventionally-housed weaners and growing fattening pigs, and gilts kept on straw).
Specification of the branched chain design
1: Object-design: A branched chain consists of a vertically-positioned long chain with its end resting on the solid floor over a distance of 20 cm. Two or three additional chain ends (branches) end at or slightly below the nose height of the smallest and middle-sized pigs reared in the pen.
2: Material: The chains are stainless-steel anchor chains (for at least the last 5-10 links of each chain end). Recommended dimensions are 7mm for growing-fattening pigs, 5-6 mm for weaners, 4-5 mm for piglets and 8 mm for sows.
Anchor chains have links which are more round and heavier than the cheaper, more oval-shaped c-chains. Note that the indicated sizes refer to the diameter of the metal, not the diameter of the links. For example, a 7 mm anchor chain for finishers has links measuring 36×23 mm. Preferably various chain sizes should be provided in the pen, esp. when the pen may contain pigs of variable sizes (e.g. from 25 to >100 kg). Stainless-steel anchor chains are more expensive, but only the last 5 or so links need to be replaced when worn e.g. every 5 – 10 years.
3: Availability and placement: One branched chain is provided for every 5 pigs.The chains are spaced apart as much as possible, preferably with at least one pig length between 2 branched chains in a pig pen. The branched chains are attached at the top end of the pen wall, over the solid floor, and not in the dunging area.