3 7 RETOMETHIONINE KETALS AND THEIR DERIVATIVES ABST=ACT 5 THE PRESENT INVENTION RELATES TO KETOMETHIONINE KETALS OR HEMIKETALS AND THEIR DERIVATIVES AND ALSO THEIR PREPARATION AND THEIR USE AS ZODDE-R ADDITIVES, I R, PARTICULAR FOR THE NUTRITION OF RUMINANTS. 10 NO SUITABLE FIGURE ON ART 1 Q 1