Nose-rings influence feeding efficiency in pigs

Nose-rings are often fitted to outdoor commercial pigs to inhibit rooting a nd reduce consequent pasture damage. During ethological observations of the behaviour of ringed pigs at pasture, subjective impressions suggested that pigs with nose-rings picked up their normal feed, in the form of large nut s ('roll nuts'), move tentatively than unringed pigs. The observed pigs wer e gestating sows under one of three treatments: unringed controls (UR), mul tiple wire 'clip-rings' through the upper rim of the snout (CR), or rigid ' bull-rings' through the nasal septum (BR). For formal assessment of feeding efficiency eight randomly selected pigs from each condition were timed and video-recorded, in individual feeder stalls, as they ate 20 3-cm long roll -nuts laid out in a standard rectilinear array in a steel-sided tray under each of five conditions: on a hard surface, on the surface of soil, on the surface of turf embedded in soil, or embedded in turf. All groups took long er to eat up their test meal from the plain surface than from the surfaces of either soil or turf and longer still when the nuts were embedded. In all conditions, ringed pigs took longer to eat their 20 nuts than did controls , with BR > CR > UR (overall mean times, pooling data from the different fe eding conditions: 118.6, 69.9 and 56.7 s respectively: P < 0.001). The diff erence between groups was greatest when nuts were embedded. Also, when nuts were embedded, ringed pigs were more reluctant to root: the latency to the ir first rooting action was delayed (mean latency across both embedded' con ditions: 29.6, 87.9 and 106.8 s for UR, CR and BR pigs, respectively: P < 0 .01. with soil and turf conditions combined) and, even after starting, a sm aller proportion of the residual trial time was spent rooting (0.11, 0.27 a nd 0.62 of the total time by EX, CR and UR pigs respectively; P < 0.001). I t is concluded that nose-ringing depresses the efficiency with which pigs f eed on solid food, especially if they have to root for it. The threat to we lfare inherent in this will be greatest when ringed pigs are in direct comp etition with unringed pigs.