5 April 2002

ET helps make short work

of it…

Embryo transfer is helping

one Cumbria dairy producer

culled out during foot-and-

mouth to rapidly restock

with a pedigree herd.

Hannah Velten reports

WHEN Peter Sherwins 55-head dairy herd was culled out on Apr 27 as an infected premises, years of selective breeding were sacrificed.

He lost about 30 pedigree imported animals, one cow family built up by his grandfather and all youngstock. Undeterred, Mr Sherwin decided not to restock with sheep – 400 ewes were also culled – but stick with dairy cows. "I just love cows, they get into your blood," he says.

And its pedigree cows he wants. "If Im going to get up at 5.30am every morning, I want to milk cows which look good."

He says it was a lucky coincidence that about the time the farm was cleared for restocking on Sept 27, a pedigree herd sale occurred in Dorset. Mr Sherwin bought 60 pedigree imported cattle from the Holmead herd, owned by Terry Cox.

These cows were all-year-round calving, which he also required. "Although we had sold our door-step delivery business, we had just invested in processing equipment before the cull. We need a consistent supply of 1200 litres of milk/day for the retailing," he explains.

However, before moving the cows up to Low Bridge Petton, Gosforth in Cumbria on Jan 10, a group of 55 commercial heifers were bought in from Wilts on Nov 28 to act as sentinels.

Mr Sherwin decided to use these as embryo transfer recipients, to rapidly increase the progeny from his new herds 6-7 main family lines. "Flushing one cow can produce eight embryos which, with a 60% conception rate, could produce four offspring in one year."

He contacted Dave Coombes and his wife Pam who operate as an embryo transfer (ET) team. Mr Coombes is a practising cattle vet with a large practice in Hants and Mrs Coombes is an embryologist – both were trained by another ET practitioner, Harry Coulthard.

One of an ever decreasing number of commercial ET teams in the country, the Coombes have 20-30 regular clients nationwide, which involves long hours and plenty of travelling.

"It is a responsible job, which requires full commitment," says Mrs Coombes.

Their work for Mr Sherwin was atypical in two respects. Firstly the number of cows involved. "Usually from a 150-cow herd, there may be three cows put forward for ET, but Mr Sherwin initially wanted seven cows flushing out of 60," explains Mrs Coombes.

The second factor was the geographical distance between Dorset, where cows were flushed and Cumbria where the recipient heifers were implanted – which meant freezing embryos.

Mr Coombes began flushing cows on Nov 15 last year and again, more recently, on Jan 4. "We decided to flush cows while they were still in Dorset, as they were settled in their environment and on their ration," he explains.

Out of six fertile flushes, 58 embryos were collected. "This result was due to the excellent management of donor cows by Mr Cox. The nutrition, health status and well being of the donor cow, as well as AI technique must all be top notch. And she must be clean and cycling," he adds.

Mrs Coombes explains that embryos are checked under a microscope at collection to assess fertility, quality and maturity. Those making the grade were frozen on farm, ideally within two hours of collection and taken to the main holding store at the Cedar Vet Group, Ringwood.

Once in Cumbria, embryos were thawed, checked again under the microscope and implanted in sentinel heifers, of at least 14 months old which had been synchronised.

Before purchase, these heifers had been tested for bovine virus diarrhoea, infectious bovine rhinotracheitis, leptospirosis and neospora to determine health status, explains Mr Coombes. "Neospora causes abortion, making a carrier eight times more likely to abort the embryo."

Pregnancy is diagnosed at 35-42 days after implantation as there is a slightly higher fall out rate with ET between 28-35 days, compared with natural conception, he adds.

Out of the four embryos which have so far been implanted, three heifers are definitely pregnant. At the last visit, 13 embryos were implanted and 41 are still frozen.

However, there are more cows to be flushed, including a Canadian cow Mr Sherwin has purchased, but which is still stuck overseas.

"Once commercial heifers have calved they will be sold, with capital reinvested in 15-20 more pedigree cows. The ultimate aim is to increase the herd to 100 cows." Then he plans to build up a reserve of cows with the right genetics to sell into Europe when export licences are finally granted.

"I have invested a lot of money into the new herd and must get a return. All Scawfell cows – the herd prefix – will be for sale at a price," he says. &#42

EMBRYO TRANSFER

&#8226 Rapidly build up family lines.

&#8226 Teamwork essential for success.

&#8226 Embryos can be frozen.