ABSTRACT
Gastric juice is a composite of hydrochloric acid and pepsin. Production and release occur in the gastric gland or fundic area of simple-stomached mammals, in the abomasum of ruminants, and in the proventriculus of fowl. Motility progressively conveys lumen contents from storage
Fig. 1 Schematic GI systems of (A,B) simple-stomached (pig and chicken), (C) ruminant (cow), and (D) nonruminant herbivore (horse) animals. The anatomical differences most obvious are those that accommodate symbiotic microbial populations. Simple-stomached animals are limited in this respect, and mammals employ an extensive colon, whereas two ceca are predominant in fowl. Ruminants acquire their microbial population prior to formal digestion, which improves overall nutrient access, whereas in nonruminant herbivores microbial action on indigesta occurs in the small intestine to enhance energy recovery. Source: Reconstructed using diagrams from Moran.[1]
Fu r-
GI
past gastric glands and then facilitates mixing for enzyme action in the antrum of the stomach and abomasum. Peristalsis also conveys food from the fowl’s crop for a brief stop in the proventriculus to acquire gastric juice before subsequent mixing in the gizzard. Circular muscle associated with the gizzard is emphasized to support intense contractions for grinding, while a tough koilin mucosa endures digestive and physical stresses.
