Luis Fernando Uribe-Velásquez

Circadian and circannual rhythms of T3 and T4 secretions in Polwarth–Ideal rams☆

Univ Estadual Paulista Julio Mesquita Filho, FMVZ, Dept Anim Reprod & Vet Radiol, BR-18618000 Botucatu, SP, Brazil

Efeitos do estresse térmico nas concentrações plasmáticas de progesterona (P4) e estradiol 17-b (E2) e temperatura retal em cabras da raça Pardo Alpina

Six lactating goats were randomly assigned to a crossover experimental design in two groups, under thermoneutral and heat stress conditions. An adaptation period of 28 days were followed by 4-periods of 14 days each, when the animals under heat stress were exposed to an average temperature of 33.34oC; THI of 86.20; BGT of 36.18 and BT of 32.11oC from 8 to 17 hours, including simulated solar radiation from 10 to 15 hours. There was no difference for progesterone plasma concentrations but the animals under heat stress showed a reduction of estradiol plasma concentrations as compared to the thermoneutral group. The rectal temperature of the animals under heat stress was higher when compared to the animals under thermoneutral conditions. The goats maintained progesterone plasma concentrations with reduction of estradiol secretion when exposed to repeat stress and intermittent in spite of the occurrence of hyperthermia during heat stress.