| heal.abstract |
Estrus synchronization was induced in Saanen goats during the breeding season by insertion of intravaginal sponges (60 mg medroxyprogesterone acetate) for 17 d followed by intramuscular injection of 500 IU PMSG 2 d before sponge withdrawal. Artificial insemination was performed at 24 and 48 h after sponge removal. Serum progesterone levels were measured throughout the treatment period and the subsequent estrous cycle. Mean progesterone concentrations were significantly different during the period with the progestagen treatment between animals that conceived (Group 1) and those that failed to conceive (Group 2, 3.7 ± 0.3 and 2.02 ± 0.2 ng/ml,respectively, mean ± SEM; P < 0.05). A paradoxical increase in progesterone concentation was evident the first and third day after PMSG administration in both groups, with values higher for the first group of animals. During the subsequent estrous cycle mean progesterone concentrations did not differ between the groups of animals until Day 37. From then on until Day 41 a significant difference was observed, with values on Day 41 being 7.6 ± 0.3 and 0.4 ± 0.03 ng/ml for the pregnant and nonpregnant animals,respectively (mean ± SEM; P < 0.001). It is suggested that enhanced luteal function during the treatment with the progestagen has a beneficial effect on the fertilization process and the rate of conception in the goat. © 1995. |
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