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Evaluation of the growth performance, feeding and activity patterns, and aggressive behavior of barrows mixed twice during the finishing period
The effect of mixing pigs twice during finishing on growth performance, feeding and activity patterns, and aggressive behavior was investigated in a study involving 48 barrows. The study was carried out over a 10-wk period (65.3 ± 4.4 kg to 136.5 ± 7.6 kg BW) as a generalized randomized block design (blocking factor day of start on test) with 2 treatments: 1) Control (Not-mixed); 2) Mixed (mixed at start and at wk 5 of the study). The study involved 4 pens of 12 pigs; pens were equipped with an electronic feed station that recorded the time and duration of visits and the weight of feed consumed/visit for each animal in the group. For the first mixing event, the 12 pigs in the 2 pens on the Mixed treatment were divided into 2 subgroups of 6 pigs with the same mean and variation in BW and one subgroup from each pen was exchanged with a subgroup from the other pen. For the second mixing event, the subgroups of 6 that were mixed had not previously been mixed together. Activity (numbers lying, standing, eating, and drinking) and aggressive interactions (number of bites and fights of greater than 3 seconds duration) were recorded on the d before and d of mixing, and d 1, 2, and 3 post-mixing. During the recording period, activity was recorded every 10 minutes and aggressive interactions were recorded continuously. There was no effect (P > 0.05) of mixing on growth performance or feeding patterns for the periods immediately after mixing or for the overall study period. Mixing increased (P ≤ 0.05) the percent of pigs standing (6.9 vs. 9.7% for Control and Mixed, respectively) and reduced (P ≤ 0.05) the percent of pigs lying (85 vs. 82%, respectively) for the 3 d following the first, but not the second (P > 0.05), mixing event. Mixing increased (P ≤ 0.05) the number of fights/pig (0.0 vs. 1.8, for Control and Mixed, respectively) on the d of mixing of the first mixing event, but not on the following days or for any day after the second mixing event (P > 0.05). These results suggest that mixing pigs in the finishing period can increase the level of aggression for a short period of time, with no impact on growth performance or feeding patterns.
Keywords: behavior, Mixing, Pigs.