Abstract Passive acoustics monitoring (PAM) is an exceptional tool to analyze the feeding behavior of shrimp, as they emit a “click” sound by the mandibular occlusion. Hence, acoustic demand-feeding systems based on the click signals energy have been applied to improve feeding management in shrimp farming. These acoustic signals may be affected by the texture properties of the foods pellets, which are modified by the manufacturing process. The aim of the present study was to evaluate the acoustic activity of Litopenaeus vannamei fed pelleted and extruded diets. Two commercial diets were used, manufactured by extrusion and pelleting processing with similar formulation (36% crude protein) and pellet diameter. Acoustic evaluation was performed with these diets offered “as is” dry and previously soaked in water for one and two hours in a 2 × 3 factorial arrangement. The pellet hardness and moisture content were also measured. The acoustic trial was performed using omnidirectional hydrophones inside acoustic foam anechoic chambers. Three fastened shrimp (10 g) were placed inside acoustic chambers and audio recordings started (30 min) when food (0.5 g) was offered. The texture of diets was closely related to the acoustic intensity (Root Mean Square Amplitude - RMS) produced by L. vannamei during the feeding activity. The greater hardness of the extruded diet resulted in higher RMS than pelleted food when offered dry, which could be an advantage for the sound detection of feeding activity. The lower RMS observed when both diets were soaked suggests that softer texture pellets can be eventually ingested without the need of mandibles occlusion, and consequently without clicking sound emission. Additionally, unusual clicks train signals were first reported when shrimp fed soaked diets, probably due to mandibles rubbing. The relationship between textural properties and acoustical responses of foods should gain more attention, especially considering the potential applications on automatic acoustic feedback systems in shrimp farming.

中文翻译：

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喂食颗粒饲料和挤压饲料的南美白对虾的声学活性

摘要 被动声学监测 (PAM) 是分析虾摄食行为的一种特殊工具，因为它们通过下颌咬合发出“咔哒”声。因此，基于点击信号能量的声学需求饲喂系统已被应用于改善对虾养殖的饲喂管理。这些声音信号可能会受到食品颗粒质地特性的影响，这些特性会因制造过程而改变。本研究的目的是评估喂食颗粒饲料和挤压饲料的南美白对虾的声学活动。使用了两种商业饮食，通过挤压和造粒加工制造，具有相似的配方（36% 粗蛋白）和颗粒直径。对这些“原样”干燥的饮食进行声学评估，并预先以 2 × 3 的因子安排在水中浸泡一两个小时。还测量了颗粒硬度和水分含量。声学试验是在声学泡沫消声室内使用全向水听器进行的。三只扣紧的虾 (10 g) 被放置在声学室内，当提供食物 (0.5 g) 时开始录音 (30 分钟)。日粮的质地与南美白对虾在摄食活动中产生的声强（均方根振幅 - RMS）密切相关。当提供干燥时，挤压饲料的更大硬度导致比颗粒食物更高的 RMS，这可能是对进食活动的声音检测的优势。当两种饮食都浸泡时观察到的较低 RMS 表明，最终可以摄入质地较软的颗粒，而无需下颌骨咬合，因此不会发出咔嗒声。此外，当虾喂食浸泡过的饲料时，首次报告了异常的咔嗒声信号，这可能是由于下颌摩擦所致。食物的质地特性和声学响应之间的关系应该得到更多的关注，特别是考虑到自动声学反馈系统在对虾养殖中的潜在应用。