仔猪肠道免疫与肠道健康

肠道黏膜免疫系统是仔猪体内最大的黏膜免疫器官,在识别和清除有害物质的过程中发挥着重要作用,同时能够对营养物质和肠道益生菌形成免疫耐受,与仔猪的健康关系最为密切。随着养殖业进入全面减抗、限抗的时代,养猪业面临巨大的挑战。仔猪肠道健康决定了猪场的生产效益,正确认识仔猪肠道免疫系统,科学调节肠道免疫,提高仔猪抗病能力,是决定养猪生产能否成功的重要因素。     

Automatic submerging and surfacing performances of model submersible fish cage system operated by air control

An automatic, submersible fish cage system using air control was developed and a set of model experiments were conducted to examine the automatic submerging characteristics of the cage. The components of the fish cage consist of a rigid frame assembly with 6 variable ballast tanks and 6 fixed ballast tanks. The variable ballast tanks were used to change the buoyancy characteristics of the system by air control so that the fish cage can either be placed at the surface or submerged. The cage is free to move vertically within a water column by adjusting the weight and the buoyancy with an air control system. The model of this system, with dimensions of 2.20 m in diameter and length and 1.04 m in net cage depth, was constructed to be 1/10 the size of the full-scale system. In the model experiments, the submerging and surfacing characteristics of the cage were regulated with measurements from a water-pressure gauge and a gyroscope incorporated into the automatic control system. Model tests were performed in a still water tank and a large wave tank to develop the algorithm required to control the cage system and to verify the ability of the automatic submersion mechanism to function. The control system was designed so that when the variable ballast tanks were flooded with water, the model descended. To raise the system, compressed air is injected into the tanks by opening the main evacuation valve on the manifold. After the required amount of compressed air is supplied, the main evacuation valves can be shut and as a result, the fish cage becomes buoyant. Measured performance results in a still water tank are then compared with calculations from a previously developed numerical technique. The submerging and surfacing characteristics of the fish cage were relatively similar to the measurements obtained with the physical model experiments using air control. The cage was submerged to a target depth when incidence wave heights were higher than the critical wave height and raised when little wave actions were detected in a wave tank. On the other hand, the cage was placed at the surface when incidence wave heights were the same as the critical wave height or lower.     

恢复养猪生产主要传染病的防控措施

我国养猪业一直面临对抗多种传染病的压力,自2018年我国发生非洲猪瘟以来,国内多地先后出现疫情,导致生猪存栏量明显下降,严重影响了人民生活,对生猪产业造成了巨大的经济损失,目前亟待恢复正常的生猪生产经营秩序。在进行防控非洲猪瘟的同时,也不能忽视其他猪场常见传染病的防控,为此文章对恢复养猪生产过程中,猪场常见传染病的防控提出了一些建议,以便供养殖户和管理者参考。