Abomasum
The abomasum ( abomasum ) is a digestive organ in ruminants (ruminantia). It is often referred to as the “fourth stomach” of ruminants. In fact, the abomasum (glandular stomach) corresponds to the actual stomach (gaster) of the monogastric animals (animals with single- cavity stomachs), while the other stomachs, i.e. rumen (rumen), reticulum and leaf stomach (psaltery) as so-called fore- stomachs, have no glandular mucous membrane.
Anatomy and topography
The abomasum is lined with glandular mucosa and is characterized by the occurrence of spiral folds. It lies in the area of the sternum- sword process of the lower abdominal wall and runs obliquely from left-front to right-back. It represents an elongated pear-shaped structure, the content of which is 10–20 liters in cattle. In newborns, the abomasum makes up about 50% of the forestomach departments. After the training of the forestomach departments, its share in the 38th week of life is only 10–20% of the entire forestomach-abomasum system.
Digestive physiology
After the food pulp in the rumen has been pre-digested by microorganisms , chewed again and dehydrated in the leaf stomach , the pH value in the abomasum is lowered (by hydrochloric acid ) and digestion begins by the body's own enzymes. An additional important function of the abomasum is the storage of food. In adult ruminants, the abomasum digestion corresponds in principle to that of the single-cavity stomach. In addition to the typical gastric motor skills in the form of an increasing muscle movement from the stomach entrance to the porter's part, characteristic fluctuations in tension of the smooth wall muscles occur in the abomasum, which are largely independent of the movements of the forestomach. The constant passage of forestomach contents keeps the abomasum moving continuously.
Milk digestion in suckling young animals
In young animals that still suckle milk , the rennet (enzyme mixture of pepsin and chymosin) is produced in the abomasum . With this rennet combined with the low pH value, the casein in the milk is broken down and the curdled milk can then be digested further. The milk is passed directly to the abomasum, it must not get into the rumen. This is initially controlled by the gullet reflex , which closes the opening to the rumen. This reflex later disappears by switching to coarse forage. In the transition period from milk to green fodder and water, however, the animals manage to channel milk into the abomasum and water into the rumen.
Diseases
The abomasum (dislocatio abomasi) is a frequently occurring mainly in dairy cows shortly after calving disease.
Processing for human consumption
Of rennet stomachs of calves is Lab for cheese production won. Abomasum are also processed into tripe specialties such as the Italian lampredotto .
literature
- Franz-Viktor Salomon: stomach, ventriculus (gaster). In: Salomon u. a. (Ed.): Anatomy for veterinary medicine . 2nd ext. Edition. Enke-Verlag, Stuttgart 2008, ISBN 978-3-8304-1075-1 , pp. 272-293.
