Young lambs may not need inoculation against enterotoxemia type D -- otherwise known as "overeating disease" -- until past the age of 6 weeks, according to Cornell University animal scientists.

Enterotoxemia type D often occurs when sheep and cattle are fed high-grain diets. The disease is of major economic concern in livestock production systems.

The Cornell scientists examined sets of triplet lambs from ewes that either were or were not vaccinated at 3 weeks prior to lambing. One lamb in each set was not vaccinated. Another lamb was vaccinated at birth and three weeks. The third lamb was vaccinated at 3 and 6 weeks.

The result: The lamb vaccination schedules had no effect on antibody response to enterotoxemia type D. However, lambs from vaccinated ewes had much higher levels of antibodies than those from unvaccinated ewes. "The ewes provide a lot of antibodies through the colostrum, which is passed along to the lambs," said Thonney. "Now we know that it is not necessary to vaccinate the lambs until at least 6 weeks of age, especially if the ewes were vaccinated."

Published in the Journal of Animal Science (September 1997), "Vaccination Schedules to Raise Antibody Concentrations Against e-Toxin ofClostridium perfringens in Ewes and Their Triplet Lambs," the study was researched and written by Michael L. Thonney, Cornell professor of animal science; Douglas E. Hogue, Cornell professor emeritus of animal science; and Cristina de la Rosa, M.S. '97, who is back living in Venezuela.

Time-management costs are no small matter in New York or national agriculture. In 1996, there were 55,000 sheep on about 1,800 farms in New York state, while the total American population of sheep is 10 million.

Hogue explains that reducing the number of vaccinations saves time and energy for those who raise farm animals. "If you have a flock of 75 lambs and now you don't have to vaccinate those 75 lambs, that's a significant time saving. It's another step in chore-reduction," Hogue said.