Design and validation of multi-parameter control strategies for fan-pad cooling systems in summer rabbit housing

In summer rabbit housing across China, most fan-pad cooling systems still rely on single-parameter temperature control. Under high temperature and high humidity conditions, improper activation or deactivation of the water pump often leads to excessive indoor humidity, thereby exacerbating heat stress in rabbits. Conversely, in high temperature and low humidity regions, starting the water pump can cause substantial indoor temperature swings. To address these challenges, this study proposes a multi-parameter control logic tailored to different climatic conditions. For high temperature and high humidity environments, a dual-parameter control strategy regulates the water pump based on indoor temperature and outdoor humidity. For high temperature and low humidity climates, a multi-parameter approach was implemented, incorporating indoor temperature, outdoor temperature, and outdoor humidity to determine water pump activation. In addition, a “prevent sudden drop” measure reduces fan speed when the pump is initially started, and “Temperature Fluctuation Mitigation Measures” adjust water circulation time to stabilize indoor conditions. Field experiments were conducted at rabbit farms in Qingdao, Shandong, and Qingyang, Gansu. The results indicate that in Qingdao, the proportion of time with a temperature-humidity index (THI) exceeding 27.8 was only 2.2% by day and 0% at night, indicating efficient pump on-off scheduling. In Qingyang, applying the “prevent sudden drop” measure tripled the time over which a sudden drop in temperature occurred, while the “Temperature Fluctuation Mitigation Measures” reduced indoor temperature fluctuation from 3 ℃ to within 1 ℃. Compared to a manually regulated Control house, this new strategy in the Treatment house lowered day-night temperature swings, decreased rabbit body temperature (P<0.05), reduced cumulative mortality by 4.1%, and increased total sales revenue by 4.3%. Overall, the multi-parameter control logic harnesses the cooling potential of the cooling pad and fans to maintain stable indoor environments in both high temperature high humidity and high temperature low humidity regions, ultimately improving animal welfare and economic outcomes.