These transgenic goats, created by Randy Lewis at the University of Wyoming , produce about a half ounce of silk from every quart of milk--the equivalent of a hundred spiders.
That's a problem, particularly when it comes to vitamin D. Federal guidelines recommend that children get 400 I.U. of the vitamin a day, equivalent to four 8 oz. glasses of milk.
An Argentine laboratory announced that it had created the world's first transgenic cow, using human genes that will allow the animal to produce the equivalent of mothers' milk.