Straw applications in growing pigs: Effects on behavior, straw use and growth

• Four straw applications were presented to 96 growing pigs.
• Straw use was the highest in the presence of a straw rack.
• Pigs showed longer periods of sustained contact in presence of the rack and feeder.
• Unwanted behavior occurred more in the presence of a dispenser with chopped straw.
• Skin lesions and growth did not differ between the four applications.

The short-term effects of four straw applications on pigs housed on slatted floors were investigated to determine differences in behavior, straw use and growth. Both the type of straw used and the design of the application might influence the attractiveness and effectiveness of the applications. To this end, four straw applications were tested simultaneously (1 application per pen), presenting them during two weeks to six pigs. This experimental set-up was repeated three times. The four applications tested were a straw dispenser (Funbar) with fully chopped straw, a MIK Toy (in rolls pressed chopped straw), a rack (long-stemmed straw) and a straw feeder (long-stemmed straw). All pigs (total n = 96) had ad libitum access to straw from one of the applications. Behavior was recorded using video cameras and analyzed per individual pig for week 1 and week 2 of each experimental set-up separately using the logistic mixed model.The rack and straw feeder were explored and manipulated the most (P = 0.02). In addition, the duration of sustained contact with the application was longer in presence of these applications (P = 0.0009). This result might be related to the use of long straw. The straw use in presence of the rack was very high, with an average straw use of 2 kg per pen (6 pigs) per week. For all applications, direct contact with the application decreased during the second week compared to the first week. However, this decrease was the smallest in pens with the MIK Toy. Synchronized use of the applications was seen to a small extent, as in most cases not more than two pigs showed application interaction simultaneously. The presence of the Funbar (straw dispenser) was associated with a higher frequency of belly-nosing (P = 0.03), nosing other body-parts of pen mates (P = 0.06) and manipulating pen fittings (P = 0.0002). It has been shown that the use of chopped straw might be related to a higher frequency of manipulating pen-mates, but it is not clear whether the type of straw explains this result. Growth and the presence of skin lesions did not differ between the applications.It can be concluded that the straw rack and feeder attract pigs to a larger extent. In addition, these applications are associated with longer durations of sustained contact. Straw use however is very high in presence of the rack. The Funbar straw dispenser is the least preferred application regarding behavioral effects. It seemed that this application did not offer growing pigs the same distraction as the other applications.