Pulido-Rodríguez Lina Fernanda, Pereira Alfredo Manuel Franco, Henrique Fábio Luís, Strefezzi Ricardo De Francisco, Pantoja Messy Hannear de Andrade, Mota-Rojas Daniel, Titto Cristiane Gonçalves
Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Duque de Caxias Norte 225, Pirassununga, São Paulo 13635-900, SP, Brazil.
Dipartimento di Scienze delle Produzioni Agroalimentari e dell'Ambiente (DISPAA), University of Florence, 50144 Firenze, Italy.
Vet Sci. 2025 Apr 11;12(4):358. doi: 10.3390/vetsci12040358.
Shearing to improve heat dissipation is common in sheep farming. This study evaluated the influence of shearing on thermoregulatory responses of crossbred sheep from adapted breeds exposed to heat stress. Ten ewes were kept in a climate chamber exposed to heat stress (10-13 h), reaching 37 ± 1.0 °C for nine days, during two consecutive periods, without shearing, and then at 14 days after shearing, evaluating all variables. Rectal temperature, respiration rate, sweating rate, ocular surface temperature, and skin temperature were analyzed at 7, 10, 13, 17, and 20 h, and blood cortisol was analyzed at 14 h on days 1, 5, and 9. Skin and sweat gland morphologies one time, on the last day. At 13 h, there was no difference in rectal temperature ( > 0.05); however, at 20 h, sheared ewes had higher values ( ≤ 0.05). Ocular surface temperature and skin temperatures were higher after shearing ( ≤ 0.05). At 13 h, both control and post-shearing groups presented a higher respiration rate ( > 0.05). Sweating rate was higher in unshorn animals ( ≤ 0.05). The glandular area was similar between treatments, and the sweat glands tended to be located more superficially. In conclusion, shearing crossbred ewes did not improve thermoregulatory responses when exposed to heat stress. In unshorn sheep, the homeothermy mechanisms are more efficient, ensuring a superior level of coping in tropical environments.
在养羊业中，剪毛以改善散热很常见。本研究评估了剪毛对来自适应品种的杂交绵羊在热应激下体温调节反应的影响。将10只母羊置于气候舱中暴露于热应激环境（10 - 13小时），连续两个时期，为期九天，温度达到37 ± 1.0°C，期间不剪毛，然后在剪毛后14天，评估所有变量。在第7、10、13、17和20小时分析直肠温度、呼吸频率、出汗率、眼表面温度和皮肤温度，在第1、5和9天的14小时分析血液皮质醇。在最后一天对皮肤和汗腺形态进行一次分析。在13小时时，直肠温度没有差异（> 0.05）；然而，在20小时时，剪毛母羊的值更高（≤ 0.05）。剪毛后眼表面温度和皮肤温度更高（≤ 0.05）。在13小时时，对照组和剪毛后组的呼吸频率都较高（> 0.05）。未剪毛动物的出汗率更高（≤ 0.05）。处理组之间腺面积相似，并且汗腺倾向于更浅表地定位。总之，杂交母羊在热应激时剪毛并不能改善体温调节反应。在未剪毛的绵羊中，体温调节机制更有效，确保在热带环境中有更好的应对水平。
