Vle CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. Il

The resultant mounting might have predisposed to leoss. It is
thought possible that the string protruding from the vulva might
facilitate loss. Slight but frequently repeated traction would
ocour at each micturition and although it was not observed,
heifers might remove the sponges by licking the vulva.

The oestrous manifestations seen during the treatment period
could be explained in part by the high rate of sponge loss but,
even so, 3 heifers showed standing oestrus whilst still retaining
sponges. One of these retained a Cronolone sponge throughout,
had a standing oestrus on the eighth day of treatment and returned
to oestrus 23 days later (10 days after sponge withdrawal).

Nilevar produced good synchronisation in those heifers which
retained sponges. Nine of the ten were in oestrus at some time
during days 1 to 5 post-withdrawal inclusive. The tenth animal
is anomalous in that she showed oestrus at no time during the
trial despite being well grown and having palpably normal
genitalia. There are too few animals to reach any final con-
clusions but further study of this compound would be justified.

Acknowledgments. The heifers, sponges, and mare serum gonado-
trophin were made available by G.D. Searle & Co. Ltd.

(1) BOYD, H., & HIGNETT, P.G. (1968). Vet.Rec. 83. 2-5
(2) CARRICK, M.J., & SHELTON, J.N. (1967). J.Reprod.Fert. 14.
: 21 - 32
(3) MAULEON, P., & REY, J. (1966). In 2nd int.Congr. Hormonal
Steroids, Milan, 1966.
(43 ROBINSON, T.J. (1965). Nature (Lond.) 206. 39-41
SHIMIZU, H., TOYODA, Y., TAKEUCHI, S., KAWAI, T., & ADACHI,S.
(1967). J.Reprod.Fert. 13. 555-558.

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