Abstract
An experiment of oestrus synchronisation by CAP (chlormadine) and the following fertility were carried out with 7 Japanese Native cattle. The range of months after the last calvings in these cows varied from 2 to 7 months, and the stage of the cycle laid between 2nd and 16th day when the treatment started. 0.05 mg/Kg body weight of CAP was daily given for 15 days per os. The oestrus appeared between 3rd and 6th day after the end of the treatment (excluded one cow of accident). Conception rate (examined by rectal palpation and non-return over 50 days) at the first oestrus was 2/6, and at 2nd 3 out of 6 (included 2 cows which return to oestrus after 51, 75 day-possibly due to early embryonic death).
Judging from the results of ovarian changes detected by rectal palplation, CAP did not depress the follicular development, however, did ovulation and oestrus. In addition, cows of younger (a few) months after the last delivery (lactating) seemed difficult to be conceived at earlier insemination.
The treated cows showed a considerable increase (ca 30 Kg in average) in body weight during and especially after the administration (so far 18 days after the end of treatment when weight measured), although slight changes were seen in controls (dry and wet, 10 each).
The case numbers of the present experiment were not enough to draw any definite conclusion, but evidences which should be carefully considered in the future trial were pointed out.
