LAUSR

Abstract This study aimed to evaluate a correlation between environmental temperature-humidity index (THI), rectal temperature (RT) and plasmatic concentration of cortisol in pregnancy rates of recipient cows in the Amazon biome. Recipient cows (n = 235) were submitted to an estrus synchronization simplified P36 protocol for a Fixed-Time Embryo Transference (FTEF). Rectal temperature of recipient cows and ambient temperature, relative humidity (RH) and dry-bulb temperature ( °C) were recorded on day zero (D0), eight (D8) and 16 (D16) of the protocol. On D16, each recipient received an embryo after the confirmation of a corpus luteum. At this moment, a blood sample was collected and cortisol concentration was evaluated in the sample with radioimmunoassay. On D41 (D33 embryo), pregnancy diagnosis was assessed (PD). The yield rates of recipient cows and pregnancy after the protocol were 66.81% (151/226) and 35.76% (54/151), respectively. Cows that became pregnant presented lower means in RT, plasmatic cortisol and THI parameters (P