Alleviating Heat Stress in Fattening Pigs: Low-Intensity Showers in Critical Hours Alter Body External Temperature, Feeding Pattern, Carcass Composition, and Meat Quality Characteristics.

Simple Summary: Pigs lack functional sweat glands, hence being very susceptible to heat stress. The optimum temperature in which pigs would thrive is around 20 °C, depending on age and weight. Pigs could achieve higher heat dissemination, e.g., by increasing body contact with the cooler ground and panting, but also through an undesirable reduction in feed intake. In addition, under conditions of severe heat stress, animals may become more susceptible even to immune challenges due to damage to the structure of the intestinal wall. Thus, heat stress can affect the proper functioning of metabolism, which, in addition to having implications on animal welfare, also affects the quality of meat and meat products. Cooling systems are not yet commonly seen on farms. Sprinkler systems are the most used cooling system, followed by water pads and fogging systems, for finishing pigs. As our climate continues to warm, monitoring daily feed intake and water consumption levels, along with the implementation of cooling systems, must become tools to minimize the adverse effects of hot weather. Heat stress is a significant environmental problem that has a detrimental impact on animal welfare and production efficiency in swine farms. The current study was conducted to assess the effect of low-intensity showers, provided during critical high-temperature hours daily, on body external temperature, feeding pattern, and carcass and meat quality characteristics in fattening pigs. A total of 400 animals (200 barrows and 200 gilts) were randomly allotted in 40 pens. A shower nozzle was installed over 20 pens (half barrows and half gilts) where pigs received a low-intensity shower for 2 min in 30 min intervals from 12 to 19 h (SHO group). Another group without showers was also considered (CON). Feeder occupancy measurement, thermographic measures, and carcass and meat quality parameters were studied. In the periods with higher environmental temperatures, SHO animals showed an increase in the feeder occupancy rate compared to the CON group. A decrease in temperature was observed after the shower, regardless of the anatomical location (p < 0.005). The treatment with showers led to higher values than in the CON group of 4.72%, 3.87%, 11.8%, and 15.1% for hot carcass weight, lean meat yield, and fat thickness in Longissimus Dorsi (LD) and Gluteus Medius muscles, respectively (p < 0.01). Pork from CON showed a 14.9% higher value of drip loss, and 18.9% higher malondialdehyde concentration than SHO (p < 0.01); meanwhile, intramuscular fat content was 22.8% higher in SHO than in CON (p < 0.01). On the other hand, the CON group exhibited higher L* (2.13%) and lower a* and b* values (15.8% and 8.97%) compared to the SHO group. However, the pH20h of the CON group was significantly lower than that of the SHO group (p < 0.001), indicating a softer pH decrease. Related to fatty acids in subcutaneous outer and inner layers and intramuscular fat, the CON group showed higher ΣSFA and lower ΣMUFA and Δ9-desaturase indexes than SHO (p < 0.05). In conclusion, the amelioration of heat stress through showers at critical times should be considered an interesting tool that improves both carcass and meat quality, as well as animal welfare. [ABSTRACT FROM AUTHOR]