22 November 1996

ET MAKES BIG STRIDES BUT…

EMBRYO transfer can speed up genetic progress

But for it to be truly economic, cows must be bred to produce milk for longer so that the calving interval can be extended to over 365 days.

And according to the University of Bristols Ian Cumming using ET to produce sexed embryos would save the problem of the unwanted male dairy calves.

But for the technology to be used more extensively in-vitro fertilisation (IVF) techniques must be improved to produce higher pregnancy rates.

"If we went to a 15-18-month calving interval, calvings a cow would drop by 25 to 35%. This would reduce calving stress and post-calving disease.

"Using robotic milking and BST milk loss from extending the calving interval is avoided, dry cow costs saved, and this would be sufficient to absorb the costs of using ET on all the cows."

He put that cost at £213 a cow because the conception rate for ET is half that of AI, and ET across the whole herd would also result in a higher culling rate, and a longer calving interval.

However, for improving the herds genetic base over a five-year period, ET is more effective than AI.

The cost of an ET calf produced by flushing a cow on the farm is £1000, he claims.

But these animals have a higher genetic value and can produce an £558 extra milk in their lifetime and can produce more replacement heifers.

The cost of buying equivalent cows is also high and where should you buy them, he questions. Producers should see their money back in two generations from using ET, he says.

"Limited flushing of a few carefully selected high performance cows within the herd maximises the overall rate of genetic gain for the herd.

The increased value of calves absorbs the cost of reduced herd fertility."n

&#8226 For more on ET turn to p40.