Abstract
ABSTRACT The aim of this study was to evaluate the effects of flunixin meglumine administration on pregnancy rates and luteal phase characteristics in bovine embryo recipients at the moment of embryo transfer. In experiment 1, in vitro produced embryos were transferred to 184 females divided as control and treated group (recipients treated with 1.1mg/kg flunixin meglumine). In experiment 2, 22 females were divided as control group; group 2 (animals submitted to a reproductive tract manipulation similar to an embryo transfer on the 7th day after estrous); and group 3 (females submitted to a manipulation and treatment with 1.1mg/kg flunixin meglumine). In experiment 1 no difference was observed between control and treated groups (40.2% and 44.6%, respectively) for pregnancy rates. In experiment 2 no difference was observed on the length of luteal phase between groups, however, animals in group 2 presented lower plasma progesterone concentrations than the control group and group 3. Therefore, we concluded that although the administration of flunixin meglumine at the moment of embryo transfer inhibited the reduction plasma progesterone concentrations, it was not effective in increasing pregnancy rates of bovine recipients.
Highlights
The genetic improvement of cattle herds is certainly the main mean by which productive efficiency and profitability of breeding systems can be improved
It was identified that manipulation of the recipient's reproductive tract at the time of embryo transfer results in the release of prostaglandin F2α (PGF2α) by the endometrium (Schallenberger et al, 1989; Wann and Randel, 1990; Scenna et al, 2005).This increase in PGF2α release by the endometrium may compromise the pregnancy rate through different pathways, such as detrimental action on embryo development or, for example, through impairment of luteal function of these recipients, which may indirectly affect embryo development (Wiltbank et al, 1989; Schrick et al, 2003; Hockett et al, 2004)
There was no difference (p> 0.05) in the pregnancy rate between the animals that were submitted to procedures classified with different scores of difficulty, regarding body condition score, pregnancy rate was 43.92% (65/148), 36.67% (11/30) and 33.33% (2/6) for animals with scores 1, 2 and 3 respectively
Summary
The genetic improvement of cattle herds is certainly the main mean by which productive efficiency and profitability of breeding systems can be improved. Despite the increase in numbers of bovine embryos transferred during the last years, the establishment of pregnancy in embryo recipients still presents high variability, which is well below the expected in most cases. This wide variation observed in pregnancy rates may be a result of several factors such as embryonic, maternal, environmental or even a combination of all (Young et al, 1998). Another study (Pugh et al, 2004) treated cows with aspirin, another cyclooxygenase-2 inhibitor, and achieved a significant 18% increase in pregnancy rate compared to control cows. More studies are required to better understand this interaction
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