Japanese Journal of Veterinary Research;Volume 28, Number 4

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ANALYSIS RELATING TO CORPORA LUTEA AND TWO CONTINUOUS ADMINISTRATIONS OF PMSG IN BEEF CATTLE

KANAGAWA, Hiroshi;ISHIKAWA, Tsune

Permalink : http://hdl.handle.net/2115/2203
JaLCDOI : 10.14943/jjvr.28.4.105

Abstract

One hundred and eight beef cattle were divided into 2 groups of 54 cattle each. The 1st group was administered 2,000 IU of pregnant mare's serum gonadotrophin (PMSG) for the first treatment, and the same dose of PMSG was applied for the second treatment 54-257 days later. The 2nd group of 54 cattle received 1,600-2,500 IU of PMSG for the first treatment and a dose increase ranging from 100 to 1,0000 IU for the second treatment 36-206 days later. Both groups received the PMSG on Days 9-14 (estrus as Day 0), and 2 days after the administration of PMSG, 25 mg of prostaglandin F_2α was injected intramuscularly. Two days after the prostaglandin F_2α treatment, estrus detection was performed and the cattle were inseminated artificially. The animals were operated at midline under general anaesthesia at 5-7 days after estrus, and a number of corpora lutea were observed in situ. In the 54 cattle of the 1st group, the average number of corpora lutea was 15.6 after the first PMSG treatment, and 11.3 after the second. In the 2nd group, 13 cattle received a dose increase of 100-400 IU of PMSG for the second treatment, which resulted in the average number of 12.0 corpora lutea after the first PMSG treatment, and 8.3 after the second. Furthermore, 31 cattle received a dose increase of 500-750 IU of PMSG for the second treatment, resulting in an average number of 6.6 corpora lutea after the first treatment, and 8.5 after the second. Finally, 10 cattle received a dose increase of 1,000 IU of PMSG for the second treatment, which resulted in an average number of 6.5 corpora lutea after the first treatment, and 10.7 after the second.

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