• small intestine
• histological
• duckling
• chick

Growth and performance parameters of chicks and ducklings depend on adequate development of the small intestine during prehatch and posthatch period. So morphological and histological parameters of this part are important indexes to describe the small intestinal development of the chicks and ducklings and, consequently, allow future growth capacity prediction. On the other hand, embryo development of small intestine could be affected by feed composition given to hen during egg laying. Therefore, it should be of great importance to extablish if maternal diet manipulation could positively influence chicken small intestine maturation. In order to better understand some aspects of this subject different trials were peformed.
The objective of the first study was to investigate the morphological and histological changes of small intestine in different poultry species and breed during prehatch and posthatch period.
In chicks all parameters studied (intestinal wall thickness, villi height, width and perimeter, crypt depth, Goblet cell numbers and argyrophil cell numbers) show an evident increase during prehatch and posthatch. Some differences has been observed comparing different parts of small intestine in the same breed or between breeds.
In Ovambo chicks, intestinal wall thickness at E15 presented the lowest value in the ileum and the highest in the duodenum. Villi height of duodenum increased more rapidly than either jejunum or ileum from E17. Villi width increased from E19 to 9day in the three sections. The perimeter of villi increased in the duodenum from E19 to 2d and from 7d to 9d; in the jejunum and ileum from E19 to hatch and from 2d to 9d. Crypt depth progressively increased in the three intestinal segments from hatch to 7d. PAS/AB Positive goblets cells increased in the duodenum and jejunum from E19 to 7d while they increased in the ileum throughout E19 to 9d. The density of agyrophil cells was highest in the duodenum and jejunum at hatch, while in the ileum the highest density value was at 2d.
Comparing Leghorn and Ovambo chicks from hatch to 9d, duodenum and ileum intestinal wall of Leghorn resulted greater than that of Ovambo. On the contrary, the latter had longer villi than that of Leghorn from E15 through 7d in the duodenum and ileum and from E19 through 9d in the jejunum. Moreover Ovambo had a significantly greater width of villi in the duodenum from hatch through 9d and in the jejunum at hatch and at 9d; the perimeter of villi was consistently higher in the duodenum and jejunum from E19 through 9d. Likewise duodenum crypt width in Ovambo was wider than that in Leghorn at 2d and 9d.
In Muscovy duckling, the height and width of small intestinal villi significantly increased with age. Villi number slightly increased from E24 to 2d, but there was a rapid decrease from 2d to 13d.
There were significant differences in the villi perimeter of duodenum and jejunum between E30 and hatching day, 2d and 9d, 9d and 13d. Increases in crypt depths were significantly affected by age from hatching in the duodenum and between hatching and 2d in the jejunum. Crypt width increased significantly only between hatching day and 2d.
In the duodenum and jejunum the V:C ratio peaked at hatching, and decreased from hatching to 2d.
AB/PAS-positive goblet cells appeared on the villi and crypts of the duodenum and jejunum at 30E, and in the ileum at hatching. The AB-positive cells, compared with the PAS-positive cells, predominated in villi and crypts of the three segments, moreover the rate of AB-positive cells to PAS-positive cells significantly decreased from 30E to 9d. The argyrophil and goblet cells distribution was variable over the length of the small intestine from embryonic day 24E to post-hatching day13d. In the duodenum the density of agyrophil cells was highest at hatching, while in the jejunum and in the ileum the highest density value was at hatching and 13d. Throughout the small intestine and in the pancreas, NPY immunoreative cells were detected from E24.
PP positive cells were observed in the pancreas from E24, in the duodenum and jejunum from E30 and in the ileum from hatch. GLP-1 positive cells were observed in the pancreas and jejunum at E24 and in the duodenum and ileum at E30. Gastrin releasing peptide positive cells were first seen in the distal duodenum at E30 while in the proximal duodenum at hatch and in the jejunum at 9d, however they did not appeared in the pancreas.
PACAP positive cells were primarily observed in the jejunum and ileum at E30 and in the duodenum at hatch.
The objective of the second study was to evaluate the effects of maternal diet supplemented with vitamin D3 (VD) and vitamin E (VE) on the development of the small intestine of Ovambo chicks during prehatch and posthatch period. VD body weight was heavier (7.1 mg) than the control (C) at hatch. VD Intestinal weight was lighter (1.45 mg) than the Control at 7 days after hatch, however, the thickness of intestinal muscle layers in the C were higher than that in VD at 2 d and 7d. Villi height was obviously higher in the VD group in the duodenum and ileum at hatch, 2d and 7d, in the jejunum at E15, hatch and 2d. Villi height of VE was higher than that of C, respectively at hatch and 2d in duodenum and at 2d in jejunum.
At E15 villi width in the VD group was higher than that in the C group in the duodenum, jejunum and ileum. Villi perimeter of VD was higher than that of C in the duodenum at E15 and E19, in the jejunum at hatch and in the ileum at 7d.
These results contribute to better understand the pattern of the morphological and histological changes of small intestine in Muscovy duck and in two different chicken breeds. Moreover, our findings suggest the effect of vitamin D and E supplemented maternal diet on the morphological changes of the small intestine in chicks.