Fertilisation rate of ewes mated to high and low prolificacy
Romney rams
R.W. Moore
Whatawhata Hill Country Research Centre, Hamilton
Proceedings of the New Zealand Society of Animal Production.
1981, 41: 224-228
Ten high prolificacy (W) rams were compared with 10 low
prolificacy (C) rams in their ability to fertilise randomly allocated
Romney ewes. Ewes remained with the rams for a period of approximately
12 hours beginning 0 to 12 hours after the onset of oestrus. Mated ewes
were killed 2 to 4 days later. Ewes from which only one cell ova were
flushed were classified as unfertilised. The W rams fertilised 67%
(29/43) of the single-ovulating ewes while the C rams fertilised 51%
(25/49), and the W rams fertilised 87% (62/71) of the multiple-ovulating
ewes while the C rams fertilised 65% (42/65). The W rams were more
successful in fertilising both types of ewes (P<0.05). Overall the
rams were more successful in fertilising multiple-ovulating ewes (76%)
than single- ovulating ewes (59%) (P<0.05).
Ten percent (8/78) of the fertilised twin-ovulating ewes where both ova
were found had one fertilised and one unfertilised ovum (incomplete
fertilisation). There was no difference between the two types of rams
in the percentage of incomplete fertilisations.
Keywords: NZSAPAB;
Last Updated 12-09-1998
