USDA's Agricultural Research Service announced over the weekend that initial results of a research project involving prion-free cattle are now available online at www.nature.com/nbt/. ARS scientists evaluated cattle genetically modified so they do not product prions - a folded protein that's linked to bovine spongiform encephalopathy. The aim was to determine if there were observable adverse effects on the animal's health.
The cattle lack a gene that produces prions, which will help scientists test the resistance to prion propagation, not only in the laboratory, but also in live animals.
ARS studied eight Holstein mails developed by the firm Hematech Inc., a pharmaceutical research company based in Sioux Falls, S.D. The evaluation of the prion-free cattle revealed no apparent developmental abnormalities. Researchers monitored the cattle for growth and general health status from birth up to 19 months of age. Mean birth and daily gain were both within the normal range for Holsteins. General physical examinations, done at monthly intervals by licensed veterinarians found no unusual health problems.
Further testing on the cattle will take three years to complete.