then stained (13) (14) and graded (ll) (12). The ewes were observed
at least once daily. The date on which a fresh keel mark was first
observed was taken as the date of oestrus. Where 50% of the ewes
showed positive smears within 14 days of its application, the
treatment was designated an "effective stimulus". The tracts were
examined on the day of slaughter; those from Group 5 & 6 were railed
in thermos flasks following slaughter in North Wales and examined
similarly.

RESULTS & DISCUSSION. Observations on the reproductive activity of
Groups 1, 2 & 3 are presented in Table 1, and the post mortem
observations on Group 4, 5 & 6 in Table 2. The re-entry of the rams
in Group 1 resulted in an increase of 39.4 in the percentage of ewes
showing positive smears., Ewes transported on the same day and then
housed (Group 2) did not show such a marked response. However an
increase of 44.4 occurred following the re-entry of the rams on day
249, Where housing was delayed until day 269 (Group 3) the ewes
appeared to remain inactive, The post mortem findings indicated that
there was no activity in Groups 4, 5 and 6 during the seven days
prior to slaughter. There was a statistically non-significant
tendency for both tracts and ovaries of transported ewes to increase
in weight and only in these ewes were follicles greater than 5 mm
recorded. The distribution of follicles over the range given in
Table 2 does not suggest that cyclic activity was imminent. Wiggan
(4) found that 2.30% of follicles were greater than 6,00 mm at the -
luteal phase of the cycle. The high percentage of ewes in Group 3
showing positive smears following housing on Day 269, suggests that
the ewes were more responsive to this treatment which had appeared
relatively ineffective when applied earlier, Most of the ewes
yielded positive smears within seven days and were, in this respect,
similar to the "positive" ewes in Groups 1 & 2. However, only 15%
failed to exhibit oestrus by the 24th day from the "effective
stimulus", compared with 39.4% and 41.1% in Groups 1 &2 respectively.
Changes in the vaginal contents of these ewes gave every indication
that ovulations had occurred and that cyclic activity had been
initiated.

The-higher incidence of more than one 'silent heat' in Groups
1l & 2 was partly responsible for the increased interval from the
effective stimulus to onset of oestrus. Nevertheless a significant
advancement in the mean date of first oestrus was recorded. This
pattern of behaviour conforms with the findings of Wiggan (4) who
reported that the onset in ewes exposed to effective stimuli on days
197 and 238, were day 249 + 2.37 - Sept 6 and day 276 + 2.13 -
Oct 3, respectively.

l, A.F. Purser, 1963 Anim.Prod. 5 (2) : Abst.219.

2. E.S.E. Hafez, 1952, J.Agric.Sci. 42: 189.

3. H.,L1l. Williams, 1966, "The Intensification of Sheep
Production". Ph.D.Thesis, University of London.

4, L1.S. Wiggan, 1967, "Studies on fertility in sheep with

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