■虽然猪的嗅觉被广泛认为是高度发达的,令人惊讶的是,人们对它们的感官能力知之甚少。这项研究旨在(a)确定哪些非社会气味猪能够检测和区分,(b)调查探索气味时表现的行为类型,(c)比较猪对不同气味的反应,以评估他们对气味的兴趣。
■杂交商业品种的生长猪(N=192)参加了实验(32-110日龄,重64.9±10.1kg)。在笔墙有两个气味插入点的测试笔中测试了异性的小伴侣对,分开55厘米。所有猪都习惯于测试围栏和实验者。在三种气味组中测试了十二种气味(八种精油和四种合成香水),每对猪用一组三种气味测试一次(三种气味的所有可能顺序总共测试了24对),总是对无气味控制(软化水)。在测试中,3种气味中的每一种都在连续3次试验中呈现(每次试验共9次;试验持续时间:1分钟;试验间隔时间:2分钟;总试验持续时间:25分钟).响应变量包括:嗅探的持续时间,与进食相关的行为(舔,咬和生根),激动行为(咬人,位移和推动),并且没有气味或控制的方法,记录每个1分钟的气味呈现。
■所有猪在反复出现时闻到的气味较少(LMM:所有气味P<0.05),并且在随后出现新气味时明显更长[LMM(3rdvs.第一次介绍):P<0.001]。特定的气味和气味类型(精油与合成香料)对嗅探持续时间没有显着影响。总的来说,与对照插入点相比,当猪探索气味时,与饲喂相关的行为和激动行为表达明显更多(配对t检验:P<0.001),和特定的气味仅影响进食相关行为的表达。
■集体,猪快递嗅探,激动,以及探索气味时与摄食相关的行为,这表明猪将非社会起源的气味视为一种资源。气味因此可以构成猪的相关富集材料。
UNASSIGNED: Although the sense of smell in pigs is widely recognized as being highly developed, surprisingly little is known about their sensory ability. This study aimed to (a) identify which non-social odors pigs were able to detect and distinguish between, (b) investigate the types of behavior expressed when exploring odors and, (c) compare pigs\' responses to the different odors to evaluate their interest in the odors.
UNASSIGNED: Growing pigs (N = 192) of crossbred commercial breeds were enrolled in the experiment (32-110 days of age, weighing 64.9 ± 10.1kg). Littermate pairs of opposite sex were tested in test pens with two odor insertion points in the pen wall, 55 cm apart. All pigs were habituated to the test pens and experimenters. Twelve odors were tested (eight essential oils and four synthetic perfumes) in groups of three odors, with each pig pair tested once with one set of three odors (all possible orders of the three odors were tested on 24 pairs in total), always against a non-odor control (demineralized water). In a test, each of the three odors were presented during three trials in a row (a total of 9 trials per test; trial duration: 1 min; inter-trial breaks: 2 min; total test duration: 25 min). Response variables included: duration of
sniffing, feeding-related behavior (licking, biting and rooting), agonistic behavior (biting, displacement and pushing) and no approach of the odor or control, recorded throughout each 1-min odor presentation.
UNASSIGNED: All pigs sniffed an odor less when repeatedly presented (LMM: all odors P < 0.05), and significantly longer at the subsequent presentation of a new odor [LMM (3rd vs. 1st presentations): P < 0.001]. Specific odor and odor type (essential oil vs. synthetic perfume) had no significant effect on
sniffing duration. Overall, feeding-related behavior and agonistic behavior were expressed significantly more when pigs explored the odor compared with the control insertion point (Paired t-tests: P < 0.001), and specific odor only affected the expression of feeding-related behavior.
UNASSIGNED: Collectively, pigs express
sniffing, agonistic, and feeding-related behavior when exploring odors, which suggests that pigs perceive odors of non-social origin as a resource. Odors may thus constitute relevant enrichment material for pigs.