In another three days, I could be qualified to stand in for the bull – and producing better results (read on).

Betsy is a mock-up of a cow's rear end, and its internal reproductive organs, made of plastic with a rope tail attached – for extra authenticity.

As Geoff Spence observes, when it is set up in one of his sheds at Lowfield Farm, Brompton, near Northallerton, it only lacks a button for squirting cack in your eye.

The idea, imported from Australia, is to teach artificial insemination without the real risk of real damage to real cows. Up to now, learners have usually had their first lesson with disembodied bits, set aside at the slaughterhouse, and their second on the real thing.

Everyone in the A.I. business knows a story about damage done to a valuable animal by clumsy use of the two-foot metal syringe which injects the dose of semen, from a sealed straw. But in today's cost-competitive world, the need for A.I. is growing and so is the need to get it exactly right. Today's demonstration has a whole range of messages. First, Asda wants to encourage its dairy suppliers to use gender-selected semen for breeding, in order to cut the number of unwanted bull calves.

More use of "sexed semen" is one of the recommendations of the committee working on alternatives to exporting live calves to Contintental veal farms ... as a result of the run of politically-effective demonstrations at Dover, a couple of years back, starring Joanna Lumley and other cuddly members of Compassion In World Farming.

Asda gets a discount on sexed semen straws from Cogent, the A.I. specialist, so they cost Asda DairyLink farmers around £20 instead of £30 or more – against £15 for a standard straw. But they hold less, too, so it is important to position the syringe accurately. Over the 10 years the technology has been developed, there have been some complaints about poor results.

Asda is here today to say that the product is nowadays a thoroughly good one. Some A.I. experts get an 80 per cent conception rate with it, on maiden heifers, which is as good as you get. Remaining problems are likely to be down to poor technique.

Cogent is here to unveil Betsy, who will be the centre of a new three-day A.I. course costing about £450. The RSPCA is here, in the shape of farming specialist Allan Pearson, to endorse sexed semen as a way forward.

And Geoff Spence's farm has been chosen for the demonstration day because he is one of the success stories of dairy farming and Asda is taking the opportunity to draw attention to all the good practice which means he makes a living out of its milk prices – 1p a litre above the standard price paid by the processor, Arla. For Geoff Spence, that makes a difference of around £35,000 a year.

He and his father Thomas have around 370 milking cows and about the same number of youngsters – including quite a lot of bulls, because breeding is one of their interests. Because of this male births have not been as much of a problem for them as for some but since Asda set up the deal with Cogent, they have been using sexed semen to fine-tune the herd.

Geoff also makes the point that having Cogent's range of sires to choose from helps him to avoid producing bulls which are too big for the mother to deliver easily.

Visiting experts cluck approvingly over the contentment they see in Geoff's animals – which have summer access to a "loafing paddock" but spend most of their times in the air-conditioned barns where they are fed. Asda's farm liaison man, Pearce Hughes, recites some of the figures.

The cooling fans feeding the air-con pipes cost £1 a day to run but make a difference of 1,000 litres a day in yield in some conditions. The roof insulation cost £10,000 to install but makes a difference of 8deg C on a hot day. Instead of straw bedding, the milkers lie on sand, which is expensive, but does not grow the bacteria which cause mastitis. The vet calls every Thursday but Geoff counts it money well spent.

"Activity meters" – or pedometers for cows, as we like to call them in the Press – are widely used and automatically monitored for the activity which says a cow is in heat, or in distress.

It all pays off in milk yields nearly double the average.

"You don't have to do it all like this," says Pearce Hughes. "But Geoff's operation makes our point that healthy cows equal healthy returns. He is at the top of his game and he has got there through investing in cow welfare. You've got to keep your mind open to new ways of working and invest as appropriate."

n For information about sexed semen and Cogent's A.I. courses, go to Other Services at cogentuk.com or call 0800 783 7258.

chris.benfield@ypn.co.uk