2.2. Microclimatic Data Acquisition System

The microclimatic data acquisition (dry-bulb air temperature (t_db) and relative humidity of the air (RH)), both inside the system and in the external environment (meteorological shelter), was performed every 5 min, 24 h·day⁻¹, throughout the experimental period, comprising three consecutive weeks (July 2021).

To collect the data in the system, the animal-occupied zone (AOZ), composed of the bed and feeding alley areas, was divided by a regular mesh (6.0 × 4.5 m) composed of 55 equidistant points, with markings made according to the facility’s constructed characteristics (Figure 1a). The sensors were installed 2.5 m above the bed level and the feeding alley floor (Figure 1b), so as to allow the passage of the tractor used for daily turning of the bed.

Measurements of the variables t_db and RH were performed using electronic components (DHT22 sensors, model AM2302; temperature measurement range from −40.0 to 80.0 °C, with 0.5 °C accuracy; humidity measurement range from 0 to 100%, with 2% accuracy; Aosong Electronics Co. Ltd., Guangzhou, China) distributed at the 55 collection points throughout the AOZ. For processing and recording the collected data, the mesh was divided into 11 collection lines (CLs), composed of 5 sensors and a data collection and recording module. Each of the 11 data collection and recording modules consisted of an Arduino Uno R3 (ATmega328 microcontroller; 5.0 V supply voltage; 16 MHz clock speed; Atmel Corporation, San Jose, CA, USA) connected to a Data Logger Shield with RTC and SD Reader (SD card slot, integrated real-time clock DS1307; FAT16 or FAT32 card formatting; 3.3 V supply voltage; Dallas Semiconductor, Dallas, TX, USA) and a 16 × 2 LCD Display (I2C Backlight Blue, 5.0 V supply voltage; 4 or 8 bits communication; Beijing Qingyuan Innovation and Technology Development Co. Ltd., Shenzhen, China), according to the methodology adapted by Freitas et al. [26]. The Data Logger Shield with RTC and SD Reader was used to control time and record data on an SD card, while the LCD display was used to visualize the date, time, t_db, and RH data recorded.

To characterize the external environment near the CBPPV, a meteorological shelter was installed, where t_db and RH data were collected. The t_db and RH records were taken using a sensor recorder (HOBO^®, model U14-002; temperature measurement range between −20.00 and 50.00 °C, with 0.21 °C accuracy; relative humidity measurement range between 0 and 100%, with 2.5% accuracy). As well as inside the facility, external data were collected every 5 min, 24 h·day⁻¹, throughout the three weeks of the experimental period.

The average daily t_db and RH data obtained in four periods of the day were used: dawn (12:00 a.m. to 05:59 a.m.), morning (06:00 a.m. to 11:59 a.m.), afternoon (12:00 p.m. to 05:59 p.m.), and night (06:00 p.m. to 11:59 p.m.). This division was carried out with the objective of identifying the occurrence of critical environmental conditions, according to the methodology adapted by Andrade et al. [27].