Animal Digestion System

Topics: Digestion, Ruminant, Small intestine Pages: 7 (2193 words) Published: January 9, 2013
Animal System
This essay focuses on the digestive system of ruminant animals like cattle, sheep, and goats. Ruminant animals are hoofed mammals that have a digestive system which enables them to utilize energy from fibrous plant material better than other herbivores. Unlike monogastric animals such as pigs and poultry, the digestive system or ruminants is designed to ferment feedstuffs and provide precursors for energy for the animal to use. Ruminant Digestive system

The digestive system of ruminants like cattle enables them to efficiently use high roughage feedstuffs, including forages. Their digestive system is composed of the mouth, tongue, gall bladder, pancreas, the four compartment stomach (rumen, reticulum, omasum, and abomasum), salivary glands, the small intestine (duodenum, jejunum, and ileum), esophagus and the large intestine (cecum, colon, and rectum) (Brooker, 5).

Mouth and Teeth
A ruminant animal uses its mouth and tongue to harvest forages and consume feedstuffs during grazing. Cattle pick up feeds during grazing by grasping and gathering the plants with their tongues and pulling them to tear for consumption. On average, cattle take from 25,000 to over 40,000 prehensile bites to harvest forage while grazing each day. They typically spend over 30 percent of their time grazing, another 30 percent of their time chewing cud, and the rest of their time idling where they are not grazing or chewing cud (Hall, 9). The roof of their mouth is a hard dental pad without incisors. The incisors on the lower jaw work against this hard dental pad. The incisors of roughage selectors are wide with a shovel-shaped crown while those of concentrate selectors are narrower and chisel-shaped. They have the same number of molars and premolars both on the upper and lower jaws. The ruminants use their teeth to crush and grind feeds during chewing and rumination (Hall, 9). Saliva helps in moistening the feeds hence making easy when chewing and swallowing. Saliva contains enzymes which breaks down the starch (salivary amylase) and fat (salivary lipase) and is also involved in recycling of nitrogen to the rumen. Saliva mainly reduces pH levels in the reticulum and rumen. A mature cow produces up to 50 quarts of saliva per day, but this depends on the amount of time they spent in chewing feeds, which stimulates saliva production. The forage and feed mixes with saliva which contains sodium, potassium, phosphate, bicarbonate, and urea when consumed, to form a bolus. The bolus then moves from the mouth to the reticulum through the esophagus by the help of muscle contractions and pressure differences. Ruminants eat rapidly hence swallowing much of their feedstuffs without chewing it properly (Brooker, 8). Esophagus

Their esophagus moves in both directions, hence allowing them to bring back their cud into the mouth for rumination (chewing of cud), if necessary. Rumination (chewing the cud) is a process where forage and other feedstuffs are pushed back to the mouth for further chewing and mixing with saliva. The chewed cud is then swallowed again and passed into the reticulum where the solid portion slowly moves to the rumen for storage, soaking and fermentation while most of the liquid portion moves from the reticulorumen into the omasum and then abomasums (Church, 13). The Stomach

The ruminant stomach occupies almost 75 percent of the abdominen on the left side and also extending to the right side. The rumen and reticulum occupy 84 percent of the volume of the total stomach, the omasum occupies 12 percent, and the abomasum occupies 4 percent. The rumen is the largest stomach compartment, holding up to 40 gallons in a mature cow while the reticulum holds approximately 5 gallons in the mature cow. The rumen and reticulum are considered one organ known as reticulorumen because they have similar functions and are separated only by a small muscular fold of tissue. The omasum holds...
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