Effects of heat stress on performance and thermoregulatory responses of Piau purebred growing pigs

Effects of Ambient Temperature on the Performance and Thermoregulatory Responses of Commercial and Crossbred (Brazilian Piau Purebred Sires × Commercial Dams) Growing-Finishing Pigs

“…Therefore, fewer nutrients would be available for growth, impairing the overall production performance, which justifies the decreased daily weight gain (21%) in heat-stressed pigs. Likewise, Santos et al [ 17 ] and Teixeira et al [ 8 ] also verified a reduced feed intake and weight gain in pigs raised under hot conditions, even in different genetic groups (genotype commercial and Piau purebred pigs, respectively), corroborating our findings. Furthermore, no matter the genotype, high temperature resulted in a worse feed efficiency, suggesting that the decreased growth performance at high temperatures reported in our study was not exclusively associated with a reduction in feed intake, but was probably due to the decreased capacity of the animals to use or allocate nutrients for growth.…”

“…According to Carabaño et al [ 7 ], heat-tolerant animals are those that, under high ambient temperature, maintain homeothermy by balancing heat production and dissipation without productive and reproductive losses. In accordance, Teixeira et al [ 8 ] suggested in a previous study a greater heat-tolerance in Piau pigs than commercial pigs, due to the decreased magnitude of feed intake impairment and preserved feed conversion rate of the native Brazilian breed at high ambient temperatures. In addition, Rosé et al [ 9 ] and Gourdine et al [ 3 ] showed genetic variation in the thermotolerance of pigs, suggesting an improvement in this trait by genetic selection.…”

“…These results were expected since Brazilian native purebred Piau pigs are recognized for their high-fat deposition [ 13 ] and lower growth performance [ 21 ]. Teixeira et al [ 8 ] have reported a reduction of more than 300 g/day in weight gain, an increase of more than 1.5 g/g in feed conversion, and a two-fold higher backfat thickness of Piau purebred pigs compared to commercial genotypes.…”

“…Respiratory rate was visually determined by counting flank movements over 15 s, then the values were calculated for one minute, as previously described [ 15 , 16 , 17 ]. Nape, dorsal and flank skin temperature measurements were performed according to Teixeira et al [ 8 ]. Briefly, images were taken using an infrared camera (C2 FLIR; FLIR Vision Systems, AB, Sweden; 0.95 emissivity and ± 2 °C of accuracy) at the level of the backline, 1.0 m away from the animal body, allowing pigs to be fully framed in the image ( Figure 1 ).…”

“…Pre-harvest handling and slaughtering were carried out according to animal welfare regulations. After skinning and evisceration, the right halves of the carcasses were stored in a cold room at 4 °C for 24 h. After this period, a transversal cut in the right-half carcass at the 10th rib region was performed to assess backfat thickness (BF) and the loin eye area (LEA), according to the method described in our previous study [ 8 ]. Briefly, BF was measured using a digital caliper (Mitutoyo Corp, Kanogawa, Japan), and the LEA was measured by tracing the longissimus dorsi muscle outline onto transparent paper, then measuring the area through ImageJ software (version 1.51, National Institutes of Health, Bethesda, MD, USA).…”