RESULTS. Although all the heifers were well grown, with body
weights of 220 kg. to 322 kg. (mean 261 kg.), 10 of them showed
no oestrous manifestation during the period from June 16th to
the beginning of treatment. Two of these 10 showed no oestrus
during or after treatment.

There was a high loss rate of sponges, only 17 heifers re-
taining the original sponge throughout the 21 day period. A
few heifers expelled sponges repeatedly. There was no peak
period for loss of the original sponge.

Fifteen heifers showed some oestrous manifestation during
the treatment period (Table I) but of these, only 5 did so whilst
sponges were still present and only 3 of these 5 were seen in
standing oestrus. Two of the three were treated with Cronolone
and one with Nilevar.

Synchronisation of oestrus following sponge removal was poor
with Cronolone but rather better with Nilevar (Table II). When
the 17 heifers which retained sponges throughout are considered
separately it is seen that Nilevar gave good synchronisation, for
of 10 animals 9 were in oestrus within a five day period. The
tenth animal showed no oestrous manifestation throughout the
period of the trial despite having palpably normal genitalia.

Only 20 of the heifers were in oestrus during the 11 day
insemination period and, of these, 13 became pregnant. On these
small numbers there were no obvious differences in fertility
relating to the progestogen used or to the cycle of insemination.
Overall fertility was as high as would be expected in a group of
normal heifers.

DISCUSSION. Sponge losses were unacceptably high and considerably
greater than reported by other workers but our sponges, which were
6 cm. in diameter, were smaller than those used by others. In the
present trial no antibiotic was used with the sponges and whilst
this might account in part for the high loss rate it is unlikely
to provide a complete explanation. It is conceivable that the
sponges could provoke a vaginitis and cervicitis that would
predispose to loss and that antibiotics could reduce this risk

but it does not seem likely that any antibiotic would remain
effective in the vagina for more than a few days and losses of
first sponges continued throughout the treatment period. In at
least some of the heifers the vagina could be dilated much more
widely when sponges were replaced than at first insertion. This,
together with the slimy secretion present in many of these cases,
probably contributed to repeated losses. Cessation of rectal
palpation because this was thought to promote sponge loss, did

not reduce the incidence of loss. From the design of the trial,
whilst half of the heifers were carrying sponges, the other half
were either undergoing normal cycles, or having synchronised heats.

 

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