Machado Simone Pereira, Caldara Fabiana Ribeiro, Foppa Luciana, de Moura Rafael, Gonçalves Liliane Maria Piano, Garcia Rodrigo Garófallo, Nääs Irenilza de Alencar, Nieto Viviane Maria Oliveira Dos Santos, de Oliveira Geyssane Farias
College of Agrarian Sciences, Federal University of Grande Dourados, Dourados, Mato Grosso do Sul, Brazil.
Center of Agrarian Science, State University of Londrina, Londrina, Paraná, Brazil.
PLoS One. 2017 Jan 6;12(1):e0168427. doi: 10.1371/journal.pone.0168427. eCollection 2017.
Three trials were carried out in a completely randomized design aiming to assess the behavior of pigs in growth phase in enriched environments. Trial 1 evaluated the effects of frequency of availability of environmental enrichment. The animals were assigned to four treatments: 1) control with no enrichment object; 2) objects provided for six consecutive days uninterruptedly; 3) objects provided on alternate days, and 4) objects provided for six consecutive days taken away by the end of the afternoon and replaced at dawn. Trial 2 assessed the effects of scent on animals' acceptance and maintenance of interest in objects. Animals were assigned to four treatments: 1) unscented object; 2) object with banana scent; 3) object with rum scent; 4) object with scents alternated every other day. Trial 3 aimed to assess the influence of environmental enrichment based on providing rewards at different difficulty levels. Animals were assigned to three treatments: 1) object with no reward; 2) object with a reward at an easy level; 3) object with a reward at a difficult level. Each trial had six days of behavioral observations every ten minutes for eight hours each day using images from video cameras. Enrichment objects stimulated the animals' natural behavior of nuzzling and exploring the environment. The way the objects were available did not impact the success of their use. Offering enrichment on alternate days or removing the objects by the end of the day was not an effective strategy to extend the animals' interest. The olfactory stimulus in environmental enrichment objects had no positive effect on extending the animals' interest on them, nor did alternating the aromas. The tactile stimulus was a key factor for object attractiveness. Providing environmental enrichment objects with rewards stimulated the exploratory behavior of pigs. The level of difficulty to obtain the reward may discourage the animals.
进行了三项完全随机设计的试验，旨在评估生长阶段猪在丰富环境中的行为。试验1评估了环境丰富物可得频率的影响。动物被分配到四种处理方式：1）无丰富物对照；2）连续六天不间断提供丰富物；3）隔天提供丰富物；4）连续六天提供丰富物，下午结束时拿走并在黎明时更换。试验2评估了气味对动物对丰富物的接受度和兴趣维持的影响。动物被分配到四种处理方式：1）无气味的丰富物；2）有香蕉气味的丰富物；3）有朗姆酒气味的丰富物；4）气味隔天交替的丰富物。试验3旨在评估基于提供不同难度奖励的环境丰富的影响。动物被分配到三种处理方式：1）无奖励的丰富物；2）容易获得奖励的丰富物；3）难以获得奖励的丰富物。每项试验每天使用摄像机图像进行八小时、每十分钟一次的六天行为观察。丰富物刺激了动物用鼻子蹭和探索环境的自然行为。丰富物的提供方式并未影响其使用的成功率。隔天提供丰富物或在一天结束时拿走丰富物并非延长动物兴趣的有效策略。环境丰富物中的嗅觉刺激对延长动物对其的兴趣没有积极影响，气味交替也没有。触觉刺激是丰富物吸引力的关键因素。提供有奖励的环境丰富物刺激了猪的探索行为。获得奖励的难度水平可能会使动物气馁。
