1374

 

TABLE 8

 

Relationship between progestagen treatment, fertilization and embryonic mortalit

 
   
   

 

All ewes treated with Cronolone sponges for 15-17 days + 750-800 i.u. PMS on withdrawal

 

Experiment 1 A B

X-breds - Mid season Lactating - 6 weeksT Non-lactating

A

 

 

 

Ewes Ewes Percent Ewes Ewes Percent
available responded responded available responded responded

M
>l
<

 

In oestrus 33 25 74.8 1L 10 90.9 N.S.
With fertile eggs 1k 7 63.6 - No data - -
With embryos (21 days) 14 1 Feal 10 4 40.0 N.S.

 

Experiment 2 S
~

Merino - Late season Lactating - &4 weeksf Lactating - 8 weeksT

 

 

In oestrus 90 85 94 .4 90 87 96.7 N.S.
With fertile eggs 29 2 720 28 18 64.3 <0.001
With blastocysts (10 days) - No data - 28 11 39,8 -
With embryos (21 days) - No data - 27 15 555,16 -

 

Experiment 3
i i

X~ breds - Anoestrus Lactating - 5 weeks Lactating - 8 weeks

 

 

 

In oestrus 45 30 66.7 48 39 8l 23 NS
With fertile eggs 30 6 20.0 39 24 6. D <0.001

 

From Fletcher (1968). Time of removal of sponges.