EVALUATING A PROTOCOL FOR FIXED TIME ARTIFICIAL INSEMINATION USING TWO PROGESTERONE IMPLANTS IN CROSSBRED EWES RAISED UNDER HEAT STRESS'2

摘要

Assisted reproduction technologies, including fixed-time trans-cervical artificial insemination (TAI), are main components in sheep improvement programs. However, TAI requires synchronizing heat in ewes using exogenous hormones at specific time intervals since its purpose is to maintain a uniform reproductive cycle within the ewe during the year. In tropical climates with temperature-humidity index (THI) above the livestock comfort zone ewes live in constant thermal stress that may alter their physiological response to exogenous hormones. The objective of this experiment was to evaluate a protocol for fixed-time artificial insemination using two progesterone implants in crossbred ewes raised under the thermal stress of Puerto Rico. The experiment was conducted in The Small Ruminant Project at the University of Puerto Rico, Mayagüez Campus. Twelve crossbred ewes (34.16 kg) raised under thermal stress conditions (THI>72) were used to evaluate a protocol using two progesterone implants (Figure 1).