Pig elimination behavior-A review

Summary in the original language of the document

Finding ways to motivate pigs to excrete in dedicated areas is of major importance for the environment, human health and animal welfare. This review investigates pigs’ excretory behaviour and the relation to the rearing and housing environment in addition to identifying important knowledge gaps in this respect. Eliminating away from the nest/lying area appears to be innate but evolves over time. Postpartum, piglets urinate and defecate close to the nest, indicating that it is difficult to influence piglets’ choice of elimination area, as this is influenced by the sow’s choice of nest area. At increased age piglets begin to excrete further away from the nest, which is probably related to the fact that piglets start to spend more time away from it. There is no indication that the sow influences the piglets’ elimination behaviour. Elimination frequency decreases with increasing age and are non-uniformly distributed across the day, mainly occurring during daytime following the activity and drinking pattern. There are indications that activity level affects elimination frequency and the amount excreted per elimination, with a concurrent risk of underestimating the nutrient load during behavioural observations. Regarding the behavioural sequence around elimination, it seems as if sniffing precedes the event and smell is suggested to play a role. However, it cannot be concluded whether sniffing is related to the selection of an area for elimination or if it is a general behaviour in the elimination area. It has been suggested that pigs seek isolation when eliminating. However, it cannot be concluded whether elimination near walls are due to pigs seeking an undisturbed location or if it is caused by limited pen space. Also, it SUBMITTED 2 cannot be concluded how far away from the nest/lying area pigs are willing to move to urinate and defecate or which factors influence the direction they move. If it is limited how far pigs are willing to move to eliminate, it seems relevant to include several elimination areas in pens with large group sizes. A change in the environment (e.g. location of feed or lying area), change pigs’ choice of elimination area, although there are individual differences in how well individuals cope. It remains unanswered to which degree the rearing environment influences the excretory behaviour later in life. Future research should focus on exploring the distance pigs are willing to move to eliminate in addition to the direction from the nest/lying area and how this interacts with the distribution of pen resources. Also, it is relevant to gain more insight as to the effect of the rearing environment on the elimination behaviour later in life.