PHYSIOLOGICAL CONSTANTS OF PELIBUEY, DORPER AND KATAHDIN SHEEP IN A TROPICAL RAIN FOREST ECOSYSTEM

Abstract

In order to determinate the physiological constants in Dorper (D), Katahdin (K) and Pelibuey (Pb) breeds such as indicator of heat tolerance in a tropical rain forest ecosystem a study was carry out at the Research Station Carlos M. Ortega, in Gualaca, Panama. Males and females pure breed (five per race) were used and kept in pastures of Brachiaria brizantha cv. Marandú. The rectal temperature (TR), respiratory (FR) and cardiac frequency (FC), environmental temperature (TA), relative humidity (HR) and the comfort index (ITH) were evaluated in the dry and rainy periods. The experimental design was a Completely Randomized in a 3 x 2 factorial scheme. TR, FR and FC were different between races and periods, however the triple interaction race*sex*period was similar, (P>0,05). The average TR and FR were 39,31; 39,28 and 39,72° C and 116, 109 and 87 breaths/minute for D, K and Pb, respectively. For the FC results showed difference (P<0.05) for the interactions race*period and race*sex; averages FC were 99 (D), 86 (K) and 128 (Pb) beats/minute. ITH 28,83 (PS) and 29,54 (PL) were considered as severe heat stress conditions. It was concluded that although the sheep were not in a comfort zone they tolerated the ecosystem conditions by activating mechanisms of thermoregulation.