progestational phase was lengthened with an average of
three days. The three animals in which the sponges were
inserted on day O were excluded pbecause of the possibility
that some might have ovulated while others had not.

2. a group which received their sponges during the second
half of the luteal phase, i.e. between day 7 and day 14.
In this group the progestational phase was lengthened
with an average of 10 days.

3. a group which received their sponges during the follicular
phase of the cycle, i.e. between day 14 and day 17.
In these animals the progestational phase was redoubled
after a short interruption.

In table 1 the synchronisation results of these groups were

compared.

sponge PMS | non-PMS

insertion | number of ewes|

 

 

table 1. Influence of time of sponge insertion on
synchronisation rate (P=0.10).

It appears that in this experiment no influence can be
demonstrated of the phase of the cycle during which the
sponges were inserted on the synchronisation rate.

Fertility. Of 119 PMS treated animals 90 (75.6 %) conceived
after mating during the synchronized ocestrus. Of 108 non-PMS
treated ewes (two ewes lost their sponges) also 90 conceived
(83.3 %). This difference is not significant (P=0.15).
During the post synchronized oestrus these percentages
increased to respectively 85.7 and 87.0.

Table 2 represents the number of pregnant animals in the
three above mentioned groups for the PMS and non-PMS treated
ewes.

 

 

 

 

 

 

 

 

 

 

 

 

 

PMS
sponge pregnant non-pregnant) % pregnant | non-pregnant
insertion |ewes ewes
gl 5T 35 4 89.7
D 7 -14 95 15 T70.0
D14 - 17 20 7 T4.1
P=0.02 P=0.05

table 2. Influence of time of sponge insertion on pregnancy.

The significant differences found in both groups are mainly
due to the rather high pregnancy rate in the group of ewes

1540