19 January 1996

High energy intakes can double flushing figures

INCREASING embryo production from maiden heifers depends on increased energy intakes, high rates of trace minerals and clipping their top-line.

This was the claim of Somerset Cattle Breeders vet Stewart Scott. Using these techniques resulted in a doubling of the number of eggs produced, a flush increasing from 2.4 to five.

He found that higher energy intakes encourage super-ovulated heifers to produce more eggs. Feeding extra trace elements and vitamins increased the fertilisation rate of these eggs. This overcame the tendency for poorer fertilisation rates achieved when more eggs were produced.

Copper, associated with long-term deficiencies in British stock, is particularly important.

"Offering extra copper reduces the size of the uterus making it easier for sperm to reach the fertilisation site. Copper may also improve embryo quality because it makes the uterus a healthier place for eggs to grow."

Clipping the top line four weeks before flushing also improved embryo production. "After clipping animals seem to thrive. It may be that when animals get cold they boost their energy intakes."

The age at which animals should be flushed is often disputed but in Mr Scotts experience the earlier she starts cycling the better the response.

He recommended taking first flushes once heifers are over 12 months. In addition it was worth avoiding heat and cold stress, keeping stocking densities low during housing, and ensuring heifers were well fed before puberty and flushing.

Mr Scott also reported that AI bulls used for fertilising cows after super-ovulation have varying success (see box.)