Contreras-Jodar Alexandra, Escribano Damián, Cerón José Joaquin, López-Arjona Marina, Aymerich Pau, Soldevila Carme, Fàbrega Emma, Dalmau Antoni
Animal Welfare Program, Institute of Agrifood Research and Technology (IRTA), 17121 Monells, Spain.
Interdisciplinary Laboratory of Clinical Analysis, Interlab-UMU, Regional Campus of International Excellence Campus Mare Nostrum, University of Murcia, 30100 Murcia, Spain.
Animals (Basel). 2023 Jul 27;13(15):2424. doi: 10.3390/ani13152424.
This study is aimed at evaluating the effect of reducing stocking density and using cooling systems to mitigate the negative effects of high temperatures in growing pigs (females and castrated males) reared in intensive conditions (from 25 to 100 kg) during summer (June to October 2020). The experimental design was a 2 × 2 factorial where pigs were provided with an evaporative cooling system and/or raised at regular or at lower stocking densities (i.e., 0.68 to 0.80 m/animal). Treatments were distributed in four different rooms containing sex-balanced pens with either castrated males or females. Temperature and humidity were recorded throughout the experiment, and the temperature-humidity index was calculated. Heat stress (HS) on pigs was measured through changes in animals' performance, animal-based indicators (dirtiness and activity budget) and physiological indicators (neutrophil/lymphocyte ratio and hair cortisol). The use of cooling, lowering stocking density and the combination of both strategies had positive effects on pigs' final body weight (+5 kg, +3 kg, +9 kg, respectively; < 0.001). The prevalence of dirtiness was similar at the stocking densities tested, and no clear effect of the cooling system was found. Both mitigation strategies lowered the physiological indicators of stress, although only hair cortisone can be considered an indicator of HS. In conclusion, both mitigation strategies are effective in improving pig welfare and performance, especially when both are combined. The severity of the stocking density effect may depend on the severity of the temperature.
本研究旨在评估降低饲养密度和使用冷却系统对夏季（2020年6月至10月）集约化饲养（体重25至100千克）的生长猪（雌性和去势雄性）高温负面影响的缓解效果。实验设计为2×2析因设计，即给猪配备蒸发冷却系统和/或以常规或较低饲养密度（即每头猪0.68至0.80平方米）饲养。处理方式分布在四个不同的房间，房间内有性别均衡的围栏，饲养着去势雄性猪或雌性猪。在整个实验过程中记录温度和湿度，并计算温湿度指数。通过猪的生产性能变化、基于动物的指标（脏污程度和活动预算）以及生理指标（中性粒细胞/淋巴细胞比率和毛发皮质醇）来测量猪的热应激（HS）。使用冷却系统、降低饲养密度以及两种策略的组合对猪的最终体重均有积极影响（分别增加5千克、3千克、9千克；<0.001）。在所测试的饲养密度下，脏污发生率相似，未发现冷却系统有明显效果。两种缓解策略均降低了应激的生理指标，不过只有毛发皮质醇可被视为热应激的指标。总之，两种缓解策略均能有效改善猪的福利和生产性能，尤其是两者结合时。饲养密度效应的严重程度可能取决于温度的严重程度。
