• Journal of Embryo Transfer
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• v.29 no.4
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• pp.321-325
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• 2014

The present study was performed on farm animals to test the effectiveness of progesterone-releasing intravaginal device (Cue-Mate$^{(R)}$ 1.56 g) and injection of prostaglandin $F_{2{\alpha}}$ ($PGF_{2{\alpha}}$) for synchronization estrus in Hanwoo cattle. The cattle were at random stage of the estrus cycle. The cows were artificially inseminated at day 7 after Cue-Mate withdrawal, using commercial semen from Korean native bulls. There was a season effect on the estrus synchronization rate. It was higher in spring (94.3%) followed by winter (93.3%), autumn (90.4%) and summer (67.2%). In summary, The results of this study revealed that season has influences on estrus behavior of cattle with no significant effect on pregnancy rate. In summary, we suggest summer reproductive management to alleviate the effects of heat stress. It should be based on intensive cooling combined with hormonal treatment. Given that different subgroups of cows benefit differently from the treatments, selective hormonal administration should be considered.

• Animal cells and systems
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• v.12 no.2
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• pp.93-96
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• 2008

In recent years, we frequently observed missmatched pairs between male Asian toads, Bufo gargarizans, and bullfrogs, Rana catesbeiana, at the toad breeding ponds, where scramble competition for mating occurred among the male toads. Thus, we performed two-choice experiments to investigate recognition ability of mates and species in male toads. The test males did not discriminate sexes, but the clasped stimulus males immediately produced release calls and stopped it while the clasped stimulus female did not. In addition, the test male toads did not discriminate reproductive state of females and even species. However, male toads chose larger individuals. The present results indicate that the main reason of missmatched amplexus by the male toads is due to 1) the lack of recognition cues of conspecifics, 2) the lack of communication tools like release calls, and 3) the larger size of bullfrogs than male toads themselves.