Growing Pigs’ Interest in Enrichment Objects with Different Characteristics and Cleanliness

Abstract

Enrichment objects can be a practical way to provide rooting and chewing material to growing pigs, on which they can express species-specific behaviors. The challenge is to provide enrichment objects that will satisfy pigs’ behavioral needs, while being practical and low-cost for the producers. Two trials were conducted to evaluate the effects of object characteristics such as design, location, cleanliness or degree of wear, on pigs’ interest over time. The first trial compared seven objects, varying in their design and location, presented individually for five consecutive days to groups of 12 ± 3 (average ± SD) pigs, weighing 61 ± 9.2 kg. The pigs’ interest in the objects was evaluated based on the frequency, total duration and mean length of manipulation with the objects. All objects were manipulated at different levels depending on their characteristics. On average, the pigs interacted more frequently (p < 0.001) with a chewable object made of three polyurethane balls, spring-mounted and anchored to the floor, and spent more time manipulating a dried wood beam on the floor (p < 0.05), which was destructible and chewable, than suspended ropes, plastics and rubber objects, and a plastic ball on the floor. The second trial used two-choice preference tests to compare objects varying in their degree of cleanliness or wear, presented in pairs to growing pigs weighing 47 ± 7 kg and housed in groups of 14 ± 1. Two identical objects were placed simultaneously in a pen over 5 days, and only one of them was cleaned or replaced daily (treatment) while the duplicate was left untouched (control). The results showed no clear preference between control and treatment objects, indicating that short-term maintenance of the objects might be unnecessary.

Providing Effective Environmental Enrichment to Pigs: How Far Have We Come?

“…Recent studies confirm lower interaction with logs presented on the floor, versus a hanging log, possibly caused by soiling with faeces [87]. However, the study on this issue by [96] found that cleaning (plastic and rubber) objects did not affect the pigs’ interaction with them.…”

A Review of the Effects of Non-Straw Enrichment on Tail Biting in Pigs

“…Furthermore, the presentation of the enrichment contributes to the observed differences in usage. Although wooden objects in general did not occupy pigs for a high percentage of their time, a wood block elevated from the floor on one side by a plastic ring that could be moved through the pen was in use by at least one pig for 65% of the time (13.5 pigs/pen), indicating that this may be a more suitable way of providing wood than suspending it or mounting it to the wall [78]. In the same study, a set of spring-mounted plastic balls attached to the floor in a close triangular pattern were also occupied frequently (33% of the time by at least 1 pig).…”

“…Furthermore, a reduction in the manipulation of floor-based enrichments due to soiling is a concern [67]. However, the aforementioned high use of the spring-mounted balls and the woodblock with ring, and an absence of an effect of regular cleaning of such devices [78] indicates that soiling is not necessarily a problem for all floor-based devices. Lastly, any enrichment that is inaccessible to the pig, e.g., items suspended too high or biting substrates that are too large for the pig to fit its mouth around, will obviously not be effective [5].…”

“…It is well known that pigs’ interest in many types of non-straw enrichment decreases rapidly in the first few days after its introduction [12,46,65,78]. It has been recommended to restrict exposure to each object to less than 2 days to preserve its exploratory value [79].…”

“…In addition to evaluation of enrichment use in the home pen, pigs’ motivation to interact with different types of enrichment has been evaluated in preference tests. Pigs showed a preference for short-term (3 min) interaction with peat or compost over wood shavings in a three-choice maze test [78]. Within the other tested non-straw categories, no clear preferences could be determined (fir chips vs. willow chips vs. spruce chips, sugar beets vs. maize silage vs. grass silage, alfalfa hay vs. seed grass vs. barley grass, and a suspended bite-rite toy vs. sisal rope vs. wood).…”