|Buhr, Richard - Jeff|
Submitted to: Poultry Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/11/2016
Publication Date: 7/11/2016
Citation: Buhr, R.J., Bourassa, D.V. 2016. The chicken alimentary tract demarcation of the jejunum and ileum junction [abstract]. Poultry Science Meeting. 95:(E-Suppl.1)198. p.67.
Interpretive Summary: none
Technical Abstract: The chicken alimentary tract differs in several ways from other domestic food production animals. Chickens are considered monogastric omnivores although the stomach consists of two adjacent segments; the chemical proventriculus followed by the mechanical ventriculus (gizzard). The names used for the segments of the chicken small and large intestines are not consistently used in the literature or reference books and the rationale for the boundary landmarks used to separate adjacent segments varies or are not provided at all. The avian small intestine consists of three sequential segments; duodenum, jejunum, and ileum. The demarcation between the duodenum and jejunum is the aborad flexure of the distal duodenum after the entrance of the bile and pancreatic ducts. The demarcation between the jejunum and ileum is frequently designated at Meckel’s diverticulum (yolk stalk) without consideration of morphology or digestive/absorptive function. Anatomically the jejunum-ileum junction can be demarcated three ways: 1) the margin of the cecal-ileal mesenteric ligaments that connect each cecum to the ileum, 2) the termination of cranial mesenteric artery, jejunalis artery, and the associated transition from long to short rete arterioles, 3) the small intestine corresponding to the termination of the ceca. The large intestine consists of the paired cecum and a short colon, and the absence of a rectum (that portion of the colon within the pelvic canal) due to non-fusion of the pubic bones and the termination of the tract into the cloaca in the chicken. The chicken's alimentary tract is short in length and the ingested feed also has a short passage time compared to other domestic animals. The frequent occurrence of antiperistaltic contractions (ingesta reflux) moves the ingesta back-and-forth among several alimentary tract segments (duodenum to crop, gizzard to mouth, and cloaca to ceca) providing repeated opportunity for further digestion and adsorption of nutrients. Providing the demarcations used in research to locate intestinal segments in presentations and publications will minimize conflicting assignment of functions to regions within and between intestinal segments.