The effect of a straw dispenser on behavior and lesions in weanling pigs

Slatted floors and liquid manure-handling systems in intensive housing systems preclude the use of large straw quantities as enrichment material for pigs. Consequently, there is a need for alternative enrichment strategies, for example, by using suitable applications providing pigs with small straw quantities, which are associated with low straw waste. The aim of this study was to evaluate the effects of a straw dispenser filled with fully chopped straw on the behavior and lesions in weanling pigs. A total of 365 weanling pigs, housed in single-sex groups (gilts and intact boars), were randomly divided in 2 groups. Half of the pigs had access to a straw dispenser (straw; n = 187), and the other half had no access to straw (control; n = 178). They were housed in the weanling unit for a period of 7 weeks (7-20 kg) and received liquid feed. One straw dispenser was provided per pen, accessible to 3 pigs at a time of 10 to 15 pigs in the pen, and positioned above the feed trough. To receive straw, pigs had to manipulate the dispensing unit on the bottom of the dispenser. Behavioral observations were carried out twice a week, and present lesions were also scored on these days by the same observer. Data were analyzed using a logistic mixed model and a Fisher exact test. No differences were found for biting behavior toward different body parts between control and straw pigs. There was also no effect of gender. In boars, aggressive behavior occurred more in straw groups compared to control groups, which might be related to competition. This finding is also reflected in more lesions on the middle part of the body in straw groups. A lack of difference in lesion scores for tail and ears between the 2 groups suggests that the dispenser provided insufficient distraction for weanling pigs compared to a barren environment. However, the position of the straw dispenser must be kept in mind, as this caused pigs to perform straw-directed behavior mainly in the feed trough. In this study, based on behavioral observations and lesion scores, it seems that the straw dispenser did not provide pigs with more advantages compared to pigs in a barren environment. Moreover, competition was observed in pens with boars, which might be related to the fact that only one dispenser was provided per pen. It should, however, be taken into account that the position of the dispenser might not have been the most suitable as it possibly caused mixing of feed and straw. (C) 2016 Elsevier Inc. All rights reserved.