Development of lipase activity in yolk membrane and pancreas of young turkeys

Two experiments were conducted to determine the development of lipase activity in the yolk membrane (YM) of poults during the embryonic period and in the pancreas during the first 16 days after hatching. A corn-soybean meal diet, formulated to contain 6% supplemental fat was used in both Experiments 1 and 2; two dietary levels (0 or .06%) of sodium taurodeoxycholate (NaTDC) were tested in Experiment 2. Samples of YM and pancreas were collected starting at Day 7 (Experiment 1) and at Day 18 (Experiment 2) of incubation and continued until Day 4 and Day 16 after hatching for YM and pancreas, respectively. Lipase activity was measured titrametrically and tributyrin was used as the reaction substrate. Total lipase activity (TLA) per YM increased from 31 mueq/min at Day 9 of incubation to a maximum of 214 mueq/min at Day 21 and then decreased through Day 4 after hatching. Specific lipase activity as lipase activity per milligram of pancreas dry weight (DW) increased from 3.1 mueq/mgDW/min at Day 27 of incubation to 15.6 mueq/mgDW/min at Day 1 after hatching. This increase continued linearly (P less than .001) to 26.2 mueq/mgDW/min by Day 16 after hatching. The TLA per pancreas averaged 400 mueq/min at Day 1 and increased to 13,000 (Experiment 1) and 8,400 (Experiment 2) mueq/min by Day 16 after hatching. Inclusion of NaTDC in the diet had no effect on pancreatic lipase activity.