Studies in Duck Nutrition 2. STUDIES OF PROTEIN AND UNIDENTIFIED VITAMIN REQUIREMENTS

THE protein requirements of duck-lings have received relatively little attention. Horton (1932) found that a ration containing 19 percent protein pro-duced definitely superior results when compared to the results obtained with a ration containing 12 percent protein. Hamlyn, Branion, and Cavers (1934) con-cluded from their experiments that the optimum protein level for growing Pekin ducklings is about 18 percent or less. Very little research work has been done on the requirements of the duck for un-identified vitamins. Hegsted and Stare (1945) reported that ducks grew poorly on purified diets unless a source of un-identified factors was supplied. They found, however, that the then unidentified "L. casei factor " (folic acid) was capable of replacing most of the activity of crude liver extract for ducks fed purified diets. In view of the lack of information on these subjects, an investigation was un-dertaken in this laboratory to determine, more precisely, the protein requirements of Pekin ducklings during the starting and growing periods, and to determine the effect of unidentified vitamins con-tained in animal proteins and other sup-plements. The results of these experi-ments are presented in this report. EXPERIMENTAL AND RESULT