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Heat tolerance of two hair sheep breeds in the Federal District, Brazil

The objective of this study was to evaluate the effect of increased environmental temperature on physiological traits of Morada Nova (MN) and Santa Ines (SI) sheep breeds in the Federal District, Brazil. Two groups (25 MN and 25 SI) were selected for study and included both pregnant (EP) and non-pregnant (EPN) ewes, aged betwen 2 and 4 years. The fifty ewes were recorded, once a month, for six months, at 8 am and 2 pm, and measurements included body weight (W), RT (Rectal Temperature), RR (Respiration rate), and CR (Cardiac Rate) were analyzed using SAS (GLM, CORR, PRINCOMP procedures) and the program GENES. The differences between the two breeds were: RT: 38.8 and 38.7°C; RR: 23.4 and 22.8 (rate/min.); CR: 99.9 and 94.0 (rate/min.), for Morada Nova and Santa Ines breeds, respectively. Difference between non-pregnant and pregnant ewes were: RT: 38.78 and 38.52°C; RR: 23.13 and 22.82 (Rate/min); CR: 96.98 and 96.36 (Rate/min), respectively. Differences between breeds were significant, as were differences between animals within groups. It was therefore possible therefore to identify animals within a breed more or less resitant to the climate conditions. This information may be used in future breeding programs.

cardiac rate; environmental; rectal temperature; respiration rate


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