29 September 1995

It can pay to absorb good sponging advice

PRODUCERS considering sponging their ewes could improve their results by heeding advice from Dr John Robinson of the Scottish Agricultural College.

He says:

&#8226 Lubricating sponges increases the chances of sheep losing them.

&#8226 All sponges should be dusted with antibiotic powder in an attempt to keep the system as bug free as possible.

&#8226 Always wash the applicator in disinfectant after each insertion.

&#8226 Make sure sponge strings are always visible.

&#8226 Take care not to force through the hymen of a gimmer.

&#8226 Most ewes come on heat 30 hours after sponge withdrawal.

Dr Robinson also points out the vagaries involved when PMSG is used in a tupping programme.

"Overstimulating the ewe can mean five or six eggs are shed ,which results in embryo mortality and only a single live lamb," he explains. "You know this has happened when the lambs birth weight is lower for its litter size than expected. The other embryos are shed from 18 to 35 days after mating.

He says you probably only need 350 international units (iu) to trigger a response, but advises against going below 300iu. "It is tricky to work out because each breed responds differently all the year round," he says.

"For example, Suffolk ewes would need 400iu each at the beginning of August, but Texels about 100iu more because they breed later in the season naturally."