Definition of the ethological patterns used.

Mixing, a common management strategy used to regroup pigs, has been reported to impair individual performance and affect pig welfare because of the establishment of a new social hierarchy after regrouping. In this study we aimed to determine whether mixing management (non-mixed vs. mixed) and gender (gilts vs. barrows) affect the social and non-social behavior, performance, and physiological parameters of pigs. A total of 96 growing pigs (48 barrows and 48 females) were separated into two treatments: control (CT)—pigs that were mixed once during the growing-finishing period; and social stress (SS)—pigs that were mixed thrice during the growing-finishing period. We recorded social and non-social behaviors, injury score, performance, and physiological parameters during the experimental period. Data were grouped by the period, based on each mix performed, and overall values. The statistical analysis performed considered gender and treatment. For treatment, during period–II and III, the SS group presented the highest frequency of agonistic interactions (AI), stayed longer lying laterally (LL) and sternly (LS), and explored more enrichment material (ER) than the CT group. Furthermore, SS pigs presented the highest injury score in the ear, head, and middle and posterior regions. Compared to the females, the barrows spent more time at the electronic feed station and initiated most of the agonistic interactions during period–II, and they presented a higher injury score for the ear and head regions during period–III. In conclusion, repeated regrouping significantly affected social and feeding behavior without severely altering performance and physiological parameters. Furthermore, different patterns of social and feeding behavior, agonistic interactions, and injury scores between barrows and females were observed. This study provides an understanding of the impact of mixing management and gender differences on pigs, and this knowledge can be used to improve swine productivity and welfare.

混群是生猪养殖中常用的管理策略，但据报道，混群后需重新建立社会等级秩序，会损害生猪个体生产性能并影响其福利水平。本研究旨在探究混群管理（非混群vs.混群）与性别（后备母猪(gilts)vs.阉公猪(barrows)）是否会对生猪的社会行为、非社会行为、生产性能及生理指标产生影响。本试验共选用96头育肥猪（48头阉公猪与48头后备母猪），随机分为两个处理组：对照组(CT)——育肥期间仅混群1次；社会应激组(SS)——育肥期间混群3次。试验期间记录了生猪的社会行为、非社会行为、损伤评分、生产性能及生理指标。试验数据按混群周期分为阶段数据与整体数据两类，统计分析同时考虑性别与处理组两个因素。在处理组对比中，与对照组相比，社会应激组在试验阶段II与阶段III的争斗互动(agonistic interactions, AI)频次最高，侧躺(lying laterally, LL)与俯卧(lying sternly, LS)时长更长，且丰容材料探索(exploring enrichment material, ER)频次更高。此外，社会应激组生猪在耳部、头部以及躯干中后区域的损伤评分更高。与后备母猪相比，阉公猪在试验阶段II的电子饲喂站停留时长更长，且发起了绝大多数争斗互动；在试验阶段III，阉公猪的耳部与头部损伤评分更高。综上，重复混群会显著影响生猪的社会行为与采食行为，但未对其生产性能及生理指标造成严重影响。此外，阉公猪与后备母猪在社会行为、采食行为、争斗互动模式及损伤评分方面均存在显著差异。本研究阐明了混群管理与性别差异对生猪的影响，相关研究结果可用于提升生猪生产性能与福利水平。