Indução da luteólise em vacas superovuladas : aspectos endócrinos e ultrassonográficos
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Data
2010-08-16
Autores
Vargas, Márcio Sérgio Bissoli
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Universidade Federal do Espírito Santo
Resumo
The objectives of this study were to compare the efficiency of luteolysis induction at different times after embryo flushing and to evaluate corpora lutea morphological and functional regression in superovulated and non-superovulated animals. In the first study, we evaluated the moment of luteolysis induction (day embryo flushing – D7 or three days later – 10). Holstein cows (N = 40) were superovulated with 400 IU of FSH (Pluset®) in decreasing doses, and after embryo flushing were randomly allocated into two groups which received 0.5 mg IM cloprostenol of PGF2a analogous (Ciosin®) on D7 or D10, respectively. The luteolysis was monitored by plasmatic progesterone, measured by solid phase radioimmunoassay, and the values were compared by analysis of variance. In cows treated at D10 was reduction in the concentration of Progesterone (P<0.05). In the group treated at D7, a portion of the animals shored no reduction in plasma concentration of progesterone to values below 1 ng/mL (P<0.05). In experiment 2 we assessed the morphological and functional luteolysis in superovulated donors. Holstein cows (n = 03) and Brahman (n = 03) (Treated Group - GT) were superovulated by application of 400 IU of FSH (Pluset®) in decreasing doses, and three days after collection of embryos (D10) received an application of 0.5 mg cloprostenol IM (Ciosin®). Crossbred cows (control group - CG) (N = 8) were synchronized and received the luteolytic agent at the same moment of the cycle (D10). The luteolysis was monitored in samples of plasma progesterone and LH, and ultrasound for monitoring of luteal regression with ultra-sonography equipment (Aquila Vet®) using a 8.0 MHz probe. The values obtained from progesterone and LH concentration, average size of CLs and total luteal area were evaluated by analysis of variance and differences between means compared by Tukey test (P<0.05). The concentration of progesterone in both groups decreased to values below 1ng/mL (P<0.05). LH concentrations showed elevated values in plasmatic concentration in both groups. The medium luteal size and luteal total area were reduced indicating morphological luteolysis. We conclude that: the induction of luteolysis is most effective when luteolytic application is performed on D10; the pattern of morphological and functional regression in induced luteolysis in superovulated animals is similar to animals non-superovulated; the higher volume of luteal tissue and the resulting high concentrations of P4 may delay the resumption of the pattern of LH release and expression of estrus.
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Progesterona , Prostaglandina , Corpo lúteo – Aspectos endócrinos , Corpo lúteo – Ultrassonografia , Vaca – Reprodução , Bovino