Cloning Advances

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9th June 2011

Article taken from: ANZBloodstock News July 6 2010

Cloning Advances

Another cloning milestone has been reached by researchers at Texas A&M University with the successful birth of a foal produced using ooxytes from a live mare. Mouse was born May 5, 2010. The efforts of his owner, Kit Knotts, to find a horse that had the same qualities as her prized Lipizzaner stallion Marc, (Pluto lll Marcells) led her to Texas A&M University and equine reproduction expert Dr Katrin Hinrichs.

"We have actually worked on this clone for about two years," said Hinrichs, a professor in the Department of Veterinary Physiology and Pharmacology. "This is actually our first foal produced using oocyetes, or egg cells, from live mares. We recovered the oocytes from our heard of research mares using the same method used to recover eggs from women for in vitro fertilisation. We used the oocytes for the cloning process, which made it difficult as we had very few to work with at any one time. During the cloning process, we tested a new technique that has been reported in mice to decrease birthing problems."

Dr Hinrichs lab is noted for achieving the first cloned foal in North America, and the third in the world with Paris Texas, who arrived in 2005. The lab has since produced twelve cloned foals.

The process began with a biopsy of skin cells from Marc, the horse to be cloned. Through the cloning process using oocytes recovered from a live mare, viable embryos were developed and sent to Hartman Equine Reproduction Centre, an embryo transfer facility in North Texas which works closely with Hinrichs's lab for transfer into the surrogate mares. Minnie, the mare carrying Mouse, stayed in North Texas for approximately 200 days, then was sent to her new home in Florida.

Minnie began to show signs of an early delivery, and was taken to the University Of Florida Collage Of Veterinary Medicine for observation and intervention. That's were Mouse arrived and was cared for by a team of neonatal experts that helped make sure he would make it through his critical time.

What problems might be expected with cloned foals?

In an article in the Journal of the American Veterinary Medical Association, Dr Aime K Johnson and others from Dr Hinrichs' lab examined their records relating to cloned foals born between 2004 and 2008.

Fourteen cloned foal were born alive. Six of these were clinically normal for all variables that were checked. These included gestation length, birth weight, foaling complications, gross abnormalities of the foetal membranes, appearances of the umbilicus, mental state of the foal, limb deformities.

Eight foals did have problems. Most common were maladjustment, enlarged umbilical remnant and angular deformity of the forelimbs. Some foals required aggressive treatment and intensive care. Two foals died, but all the others responded to treatment. All twelve foals that survived have remained healthy.

Because of the risk of complications and problems in the period just after birth, Dr Hinrichs' team recommends that foals derived by cloning should be treated as high-risk neonates, and their birth should be closely supervised. Facilities for intensive care should be available in case they are needed.

They suggest that supplementary oxygen should be on hand. Plasma transfusion may be required, as failure of passive transfer of immunity is frequently a problem - even when the mare's colostrum quality was adequate. The umbilicus must be monitored closely and treated aggressively should signs of infection appear.

Once past the critical first few days of life, foals delivered by cloning appear to be healthy and can be expected to grow normally.

Article taken from: ANZBloodstock News July 6 2010