Milk and meat from cloned cattle are almost identical in composition to the milk and meat from conventionally bred cattle, according to the first comprehensive assessment of the nutritional value of food from clones.
The new findings, by researchers in Connecticut and Japan, bolster industry assertions that food products from clones should be allowed on the market. But other experts criticized the report as incomplete and said that, in any case, social and economic factors argue against the sale of clonal food.
High-producing dairy cow Aspen, right, is seen with her clones in 2000. The clones were used for studies of milk production and compositional analyses.
(University Of Connecticut)
In one of their few points of agreement, proponents and opponents concurred that the issue remains highly politically charged -- perhaps explaining in part why a government decision on whether to allow such foods on the market has been stalled for 18 months.
"Some people do have concerns," said study leader Xiangzhong Yang, director of the Center for Regenerative Biology at the University of Connecticut at Storrs. "I think it will take time for people to accept it."
Cloning technology allows scientists to create genetic replicas of adult animals. Although the process remains expensive and inefficient, some producers see a future in the approach because it could allow farmers to mass produce their best milk cows and their finest beef cattle without diluting those stocks with a mate's lesser genes.
The National Academy of Sciences in 2002 concluded that meat and milk from cloned cattle were unlikely to pose human health concerns, but it warned that there were few studies on which to base its conclusion. A year later, a Food and Drug Administration advisory committee leaned the same way, but several members expressed reservations and even more voiced concerns about the clones' health and welfare.
The FDA has asked companies experimenting with the approach -- only two are poised to enter the market quickly -- to hold off selling their products until the issue is resolved. But a final decision has been slow in coming, frustrating the nascent livestock-cloning industry.
The new study, described in this week's issue of the Proceedings of the National Academy of Sciences, compared the chemical composition of milk from clones of a 13-year-old, high-producing Holstein cow with milk from conventional Holsteins raised identically. Tests on more than 1,000 samples found no significant differences in levels of protein, fat, lactose, antibodies and other parameters routinely monitored by the dairy industry.
The team also studied clones of the offspring of a prizewinning Japanese bull famed for his superior marbling -- the blend of fat and muscle that contributes so much to a steak's quality. Of more than 100 measures, more than 90 percent were virtually identical for the clones and conventional animals. Of the dozen tests on which clones scored differently, most showed they had higher levels of fats or fatty acids in various cuts -- traits valued by many consumers, the researchers reported. That reflects the high fat levels in the bull that sired the cloned animal -- one of the reasons that semen from that bull has been used to produce more than 165,000 offspring by standard in vitro fertilization methods.
Carol Tucker Foreman, director of the Food Policy Institute at the Consumer Federation of America and an assistant secretary for food at the Agriculture Department under President Jimmy Carter, called the study "limited in scope" because of the small number of animals involved and because it did not address such issues as whether the clones were more susceptible to infection or other microbial problems, as some critics suspect.
Social and ethical questions also persist, Foreman said.
"This study does not address the big issue . . . which is: 'Is this what we want to do as a society? What do we think about having a clone burger?' We still need to have a national conversation about that."
The Humane Society of the United States has asked for a ban on milk and meat from clones, noting that many clones die mysteriously during gestation or soon after birth. Others have wondered aloud why it is necessary to clone cows that produce huge amounts of milk when surpluses, rather than shortages, are the main problem facing the U.S. dairy industry today.
But Barbara Glenn, director of animal biotechnology for the Biotechnology Industry Organization, said it is time to allow the new products on the market.
"These are the best and healthiest and highest-producing animals," Glenn said, adding that "the science is clear" that clonal meat and milk are equivalent to conventional foods. In terms of animal welfare, she added, clones "are basically the rock stars at the farm . . . and are receiving the best veterinary care that an animal can have."
High-producing clones can help poor farmers, added Yang, who has helped start a company that aims to spread the technology to developing countries.
An FDA spokesman said yesterday that the agency is close to releasing its draft risk assessment for milk and meat from clones and their offspring and would then seek public comments on the issue.