Adaptabilidade de ovinos Soinga e Santa Inês em função da dieta e do ambiente térmico.

Abstract

he objective of this study was to evaluate and compare the adaptability of the Soinga and Santa Inês genotypes as a function of diet and thermal environment through physiological, hematological parameters and heat tolerance tests. Twenty - four male, uncastrated sheep with approximately 150 days of age and mean initial live weight of 20.00 ± 3,00 kg were used. The diets used were sorghum silage and concentrate with voluminous: concentrate ratio (50:50 and 70:30). It was evaluated the ambient temperature, relative humidity and black globe temperature, black globe temperature index and humidity, thermal radiation charge in the shade and in the sun. The physiological parameters evaluated were respiratory rate (FR, mov m-1), surface temperature (TS, ° C) and rectal temperature (TR, ° C), blood glucose levels, hematological parameters, differential leukocyte count, of heat tolerance and coefficient of heat tolerance. The averages were compared by the Tukey test at the 5% level of significance. The averages of the environmental variables, the black globe temperature index and moisture and the thermal radiation load were above that recommended for the ovine species. There was interaction (P <0.05) of the genotypes with the environment in relation to TS and TR. The Soinga genotype showed lower temperatures than Santa Inês. Immediately after stress, RF was (P <0.05) higher than in pre and post stress environments. The glucose levels were statistically different (P <0.05) in all evaluated factors, although the averages observed did not exceed the reference values. There was a difference (P <0.05) in erythrocyte constituents, hematocrit, HCM and CHCM as a function of the collection times, and these remained within the reference values for sheep. Immediately after stress, CTC was (P <0.05) higher than in pre-stress environments. The diets did not influence the physiological responses and the heat tolerance of Soinga and Santa Inês genotypes. However, the thermal environment had an effect on the physiological parameters of the genotypes, and Soinga was also tolerant to heat stress conditions when compared to Santa Inês. The physiological and hematological parameters of the two genotypes remained within the reference values for sheep, with the exception of respiratory rate that was elevated in all evaluated factors.