By Sarah Carey
GAINESVILLE, Fla.---To catch the latest development in invitro fertilization, steer your attention to the cattle pen. That sound you hear might be test tubes clinking.
For the first time at the University of Florida's Veterinary Medical Teaching Hospital, researchers have successfully performed an invitro fertilization procedure in cattle. Previously only commercial laboratories are thought to have performed the procedure for a private client in the United States.
"It was also the first time that any invitro produced animal has been delivered at the teaching hospital; actually, we delivered four calves within one week," said Dr. Maarten Drost, professor of reproduction at UF's College of Veterinary Medicine.
Within one month, two of the four calves, all delivered by Caesarean section, died because of health complications.
The surviving calves, now almost 2 months old, are thriving on Don Bennink's North Florida Holsteins dairy farm in Bell, about 40 miles northwest of Gainesville.
Known as "No. Fla. Major" and "No. Fla. Colonel," the calves are healthy and weigh approximately 250 pounds apiece, up from 110 and 108 pounds each at birth, Drost said. The big-eyed, black-and-white half-brothers are indistinguishable from the other calves housed at the farm's feed lot as they stare at onlookers and munch on lunch.
Drost said the calves are high quality and were produced from genetically desirable cows headed for slaughter. Because of health conditions including chronic hip lameness and an abnormal uterus, the donor cows were unable to produce offspring through normal reproductive methods. Their eggs were fertilized and cultured in the test tube, then transferred into healthy, surrogate mothers.
"It was a great learning experience," said Drost. "It took a tremendous team effort involving our veterinary reproduction section, the people at North Florida Holsteins and several people at UF's Institute of Food and Agricultural Sciences to make this happen."
Cows with attributes such as high milk production, disease resistance and physical configuration are considered extremely valuable by the dairy industry. Other superior features include fertility, strong feet and legs and certain functional characteristics such as good udder attachment, which lowers the risk of mastitis.
"Many of these traits lead to longevity and high lifetime productivity in terms of milk and calves," Drost said. "The payoff for the owner is the multiplication of genetically superior animals, and the production of several calves from one cow within one year rather than a single calf -- occasionally twins -- per year."
Bennink was pleased with the outcome.
"There was no way to produce any progeny without going through this procedure," said Bennink, whose farm is home to 6,500 head of cattle -- 3,600 of which are of milking age. "The only way to get offspring from these cows was to literally remove the eggs from their ovaries and fertilize them."
Drost first became involved when Bennink contacted him by phone last summer to ask if UF veterinarians could use invitro techniques to produce offspring from the nonfunctional cows.
"I synchronized the cows' estrous cycles and we removed their eggs," Drost said.
"In the end, we came up with eight good-quality embryos."
Meanwhile, Bennink identified eight recipient cows. Placing the embryos inside the uteri of the recipients was the next step.
"This took a large number of people," Drost said. "We worked closely with dairy science personnel to help manage and carry the surrogate mothers to term."
While his farm has pursued invitro fertilization through commercial facilities, the procedure generally is considered highly technical and requiring considerable experience, Bennink said. "Only certain people are doing it. It was nice to find out we could do this so close to home."
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