Cloning Project Allows Aging
Steer To Produce Offspring

By David Bowser

COLLEGE STATION — A calf produced by a steer — and a dead steer at that. Science fiction? No, science fact.

Scientists at Texas A&M University have successfully produced what is believed to be the first calf cloned from an adult steer.

Researchers Jonathan Hill and Mark Westhusin, veterinarians, proudly displayed the three week-old clone of a 21 year-old Brahman steer this month. The bull calf has the added distinction of being from the oldest animal ever to donate genetic material for cloning, A&M officials say.

The 2200 pound DNA donor, named Chance, was cloned by the duo in a year-long project. The "offspring," named Second Chance, exhibits identical markings to his "father" and has almost identical DNA.

"The calf will get just a smidgen of genetic material from the egg," Hill says. "We can't remove all of it, but we remove more than 99 percent. There are about 20 genes left."

The genetics of the host cow will not affect the calf, Hill says, except with regard to size at birth. Second Chance weighed 87 pounds when his surrogate mother, called 007, gave birth to him.

"If you have 10 identical clones," he says, "their birth weights will vary."

But that has to do more with the birth canal than the genetics of the cloned animal.

University officials say the successful cloning effort could dramatically impact the multi-billion dollar beef cattle industry.

"This could lead to new opportunities in cattle breeding, and for that matter, other animals," Hill says.

Using such methods, Hill says there is the potential for taking cells from a steer that grades Choice in the packing plant and cloning an entire herd.

"That's what the Japanese want to do," he notes.

He says they are heavily investing in such programs.

"They want to find out which carcass is the best, and clone them."

Hill says as an animal goes into a packing plant, a chunk of cells could be taken, put into a refrigerator in a sterile bottle and carefully handled and held long enough to grade the carcass. The cells could even be held long enough to taste test the meat from the animal.

"There is the potential for that," Hill avows.

It is an expensive program right now, he concedes, and there are no guarantees, but as the efficiency gets better, the cost of such a project would come down.

"That may well be the way to develop herd bulls," Hill speculates.

Some companies are getting close to offering cloning on a commercial basis, he says.

Initially, it will probably cost between $10,000 and $20,000.

"The problem is, you can't promise anything yet," Hill says. Consequently, reputable companies aren't ready to offer cloning because they don't know if every effort will get a result.

Hill expects it will be another one or two years before commercial cloning will be available in the beef industry.

"Definitely within five years," he predicts.

The decision to be made in cloning will depend upon the results the producer wants.

In a dairy herd, Hill says, the emphasis may be on the cow herd, while in a beef cattle operation, it may mean the cloning of bulls.

"In the future, there is good potential for a line of dairy cows all adapted to an area and being high producers," he says. "For the beef producers, hopefully, it will give the best bull. It's at the top of the breeding pyramid, so these breeding companies may use cloning to get more of their top bulls."

Those bulls, in turn, could produce semen for commercial herds.

For the moment, he says, cloning would probably best be used for when a top bull dies or becomes infertile. With cloning, that bull's genetics can be retrieved.

Both of those driving forces came into play with Chance and Second Chance.

"The owners of Chance, Ralph and Sandra Fisher of Swiss Alp, Texas, wanted to have their prized bull cloned because of his unusually gentle nature," Hill says, "and they considered the cloning effort a good opportunity to see if an identical copy of Chance might also have such an easy-going disposition."

Hill, the lead researcher in the project, explains that Chance was unable to reproduce naturally because of the removal two years ago of both testicles, which were diseased. Cloning him was the only option for preserving his genetics.

Chance was calm around people, did several television commercials, performed in the Houston Rodeo, and was on "The Late Show with David Letterman."

"They are looking forward to seeing if Second Chance lives up to his heritage," Hill says.

Second Chance is an intact male and should be able to sire offspring when he reaches puberty, he notes.

Chance died a few months ago, shortly before his DNA was used to produce Second Chance. Hill says there is considerable interest in keeping track of Second Chance because of the age of the cells used to clone him.

Last spring, researchers said the DNA of Dolly, the first cloned sheep, had some characteristics of the older cells that were used to generate her.

"The chromosomes, which package the animal's DNA, have some special DNA at their tips called telomeres," Hill explains. "These small pieces of DNA help to protect chromosomes from damage. Very young animals have long telomeres, but as the animal ages, the telomeres are worn away. We should know in a month or so if the telomeres of Second Chance are like those of the 21 year-old bull used as a source of the cells for the cloning process, or if they are more like those of a normal newborn calf."

Because Second Chance came from the oldest animal cloned to date, he has been intensively monitored since birth by a team of veterinarians and intensive care technicians at the Texas A&M University Large Animal Hospital, university officials say.

"We have plans to look at his cells and see if we do see aging effects," Westhusin says. "We want to look at his general physiology to see if he's acting like a normal calf."

Like many previously cloned calves, at birth he displayed some symptoms resembling those in premature human babies. Hill says, however, that Second Chance's health now is good.

Hill says it took 189 tries before a pregnancy resulted in the delivery of the bull calf. They transferred 189 cells into 189 different eggs.

"A lot of that was test tube wastage," Hill admits; they actually inserted 26 eggs into cows.

"What that represents is two weeks' solid work by a team of three people," Hill says.

That investment has to be reduced to make it commercially viable.

"What we need is an egg and a cell," Hill says, reducing the process to its simplest terms.

The egg has the DNA removed by microsurgery. The egg and the cell are then joined together using an electronic current. They let the egg divide in the test tube for about a week and let it grow to about 100 cells.

"Then it's ready for implanting," Hill says.

Unfortunately, along the way, eggs die in the test tube, but the odds are improving as techniques are perfected.

"There are labs that are getting very, very good with this," Hill says. "That 189 can be improved upon, and we expect that by next year."

The technology used by Hill and Westhusin is the same as that used in similar projects since the Scottish sheep, Dolly, was cloned in 1997.

Richard Adams, dean of the Texas A&M College of Veterinary Medicine, says because he had been castrated, Chance's ability to propagate had been lost. Cloning was the only way to pass along his genetics.

Hill was a veterinarian in Australia for 10 years before coming to Texas A&M four years ago. He used the cloning work as part of his doctor of philosophy studies in physiology with Westhusin. In October, he'll be going to Cornell as a professor of animal reproduction at the veterinary school.

The Chance-Second Chance cloning was funded by the Texas Coordinating Board of Higher Education's Advanced Research Program and by Dr. Charles Looney of Ultimate Genetics.