INTUBATION OF WEIGHT-SELECTED CHICKS WITH SOYBEAN OIL OR RESIDUAL YOK- EFFECT ON EARLY GROWTH AND DEVELOPMENT

Experiments were conducted to study the role of residual yolk on growt h and development of chicks during the 1st wk after hatch. Surgical re moval of the yolk sac at hatch reduced early body weight gains. Intuba ting chicks with a mixture of soybean meal and soybean oil or with res idual yolk obtained from chicks at hatch increased body weights and en hanced development of the liver and pancreas. Whereas intubation with residual yolk reduced absorption of yolk sac contents, absorption was similar for chicks that consumed mash ad libitum or were intubated wit h the soybean meal-soybean oil diet. After cessation of yolk intubatio n, absorption of residual yolk resumed. Removal of the yolk sac decrea sed amylase and lipase activity in the pancreas. In the intestinal chy me, activity of amylase, trypsin, and chymotrypsin was reduced by yolk sac removal. Intubation with yolk increased enzyme activity (amylase expected) in the pancreas or intestinal chyme only in chicks that had their yolk sacs removed. There was evidence that contents of the yolk sac did not enter the intestine via the yolk stalk, but were absorbed directly via the blood.