Avaliação do fotoperíodo e duração do protocolo com progestágeno sobre a concentração plasmática de progesterona em ovelhas inseminadas em tempo fixo

Abstract

The aims of this study were to evaluate, in spring and summer (November to March), the plasma progesterone concentration in woolly and hairless ewe sheep created in western São Paulo; evaluate the plasma progesterone concentration as a function of residence time of progestogen (6 , 9 or 12 days) in TAI protocol (fixed-time artificial insemination). Experiment 1: We used 12 sheep cross breeds (6 hairless hair and 6 woolly ewe), in which were made between November and March, eight blood samples (C1 to C8), by jugular venipuncture for later determination of progesterone by radioimmunoassay (RIE). Experiment 2: We used 38 sheep cross breeds randomly divided into three groups: G-6 (n = 13), G-9 (n = 13), and G-12 (n = 12). Initially each sheep received an intravaginal sponge progestogen (D0) that has remained for 6 (G-6), 9 (G-9) or 12 days (G-12). At sponge removal were administered intramuscularly, 0.1315 mg of PGF2a and 300UI eCG. The IATF, laparoscopic, was made from 50 hours after withdrawal of progestin. Thirty days after pregnancy diagnosis was performed by transabdominal ultrasound Exp 1. With the exception of crops 4 (C4) and 8 (C8), all other wooless group P4 concentration showed statistically superior (p <0.05) than the group of lanadas. Exp 2. Upon withdrawal of the progestogen G-12 P4 concentration showed significantly (p <0.05) lower (0.342 ng / mL) to G-6 (1,684 ng / ml) and G-9 (1.762 ng / mL). However there was no difference in pregnancy rates between groups G-6 (76.9%), G-9 (61.5%) and G-12 (91.6%). The hairless ewes showed plasma P4 greater than the woolly sheep in periods. The duration of stay of progestin does not affect the pregnancy rate in ewes. The duration of stay of progestin does not affect the pregnancy rate in sheep, but the sheep in G-12 P4 exhibited lower when compared to G-6 and G-9.