Developmental Patterns of Selected Characteristics of the Gastrointestinal Tract of Young Turkeys

Developing embryos and hatchling poults were sampled (n = 4) at Days 22, 24, 26, and 28 of incubation and at 1, 2, 4, 6, and 8 days after hatching, and selected characteristics of the gastrointestinal tract (GIT) were measured. Body weight increased linearly up to day of hatching and also from 2 to 8 days posthatching. Residual yolk weight decreased rapidly starting on Day 26 of incubation and was nearly depleted by 4 days posthatching. Changes in weight of segments of the GIT nearly paralleled the increase in body weight until day of hatching. Thereafter, weights of the proventriculus, small intestine, and pancreas increased more rapidly than body weight until 6 days after hatching. At this time, change in weight of small intestine and pancreas seemed to parallel that of body weight, whereas proventriculus weight continued to increase more rapidly. Gizzard weight, as a percentage of body weight, increased until Day 4 posthatching and then remained relatively constant through 8 days. Specific activities (SA) of pancreatic amylase, lipase, and trypsin were low until after hatching. Subsequently, amylase SA increased nearly threefold by Day 6. Lipase SA remained nearly constant between Days 1 and 8, and trypsin SA increased only slightly. Total activities of pancreatic enzymes, however, increased substantially after hatching, mainly because of increased pancreas weight. Jejunal maltase SA was high at hatching but decreased markedly by Day 4. This decrease in SA resulted in a notable reduction in total maltase activity of the jejunum despite an increase in jejunum weight.