ALABAMA A&M AND AUBURN UNIVERSITIES Digestive System of UNP-0060 Goats

Introduction

Mature goats are herbivorous ruminant animals. Their digestive tracts, which are similar to those of cattle, Esophagus sheep, deer, elk, bison, Large Intestine Cecum and giraffes, consist of the mouth, esophagus, four Rumen stomach compartments, (paunch) small intestine, cecum, and large intestine. A brief Reticulum description of the anatomy (honeycomb) and physiology of the mouth and the stomach Omasum Small Intestine Abomasum (manyplies) compartments of goats (true stomach) follows.

Mouth: Like other ruminant animals, goats have no upper incisor or canine teeth. They depend on the rigid dental pad in front of the Figure 1. The digestive tract of goats. hard palate, the lower incisor the type of feed. It is absorbed through the rumen teeth, the lips, and the lined with small fingerlike wall and provide as much as tongue to take food into their projections called papillae, 80 percent of the animal’s mouths. which increase the total energy requirements. Microbial digestion in the Esophagus: This is a absorptive surface of the rumen is the reason that tubelike passage from the rumen. This compartment, ruminant animals effectively mouth to the stomach. The also known as the use fibrous feeds and are esophagus, which opens into paunch, contains many maintained primarily on the stomach at the junction microorganisms, such as roughages. of the rumen and reticulum, bacteria and protozoa, helps transport bothARCHIVE gases that supply enzymes to Rumen microorganisms also and cud. break down fiber and other feed parts. Microbiological convert components of the feed to useful products such Rumen: This is the largest activities in the rumen result as essential amino acids, of the four stomach in the conversion of the B-complex vitamins, and compartments of ruminant starch and fiber of feeds to vitamin K. Afterward, the animals. The capacity of the the volatile fatty acids acetic, micro-organisms themselves rumen of goats ranges from propionic, and butyric acids. are digested in the small 3 to 6 gallons depending on These volatile fatty acids are

www.aces.edu intestine to free up these compartment. The capacity Small Intestine: As nutrients for the ruminant of the reticulum of goats partially digested feed enters animal’s use. ranges from 1/4 to 1/2 gallon. the duodenum, the first part of the small intestine, In the process of Omasum: This the enzymes produced and digesting feeds, rumen compartment, also known secreted by the pancreas microorganisms also as the manyplies, consists and the Brunner’s glands of produce large amounts of of many folds or layers of the duodenum further break gases, primarily methane tissue that grind up feed down feed nutrients into and carbon dioxide. The ingesta and squeeze some simple compounds. These animal normally eliminates of the water from the feed. compounds are absorbed these gases by eructation The capacity of the omasum into the bloodstream or (belching). When the gases of goats is approximately 1/4 lymph by an active process are produced faster than gallon. carried on largely in the the animal can eliminate jejunum and ileum (second them, a potentially lethal Abomasum: This and third part of the small condition known as bloat compartment is often intestine, respectively). can result. This condition is considered the true stomach The small intestinal wall often associated with the of ruminant animals. It is lined with many small rapid consumption of large functions similarly to human fingerlike projections called amounts of leguminous stomachs. The mucosa villi, which increase the vegetation. of the fundus contains absorption area of the small parietal cells, which secrete intestine. The capacity of the Reticulum: This hydrochloric acid, and small intestine of goats is compartment, also known as chief cells, which secrete approximately 2 1/2 gallons. the honeycomb or hardware the enzyme pepsin. This stomach, is located just enzyme is secreted in an Cecum: This simple tubular below the entrance of the inactive form (pepsinogen), structure, also known as the esophagus into the stomach. which is then activated by blind gut, is located at the When goats swallow foreign hydrochloric acid. Pepsin junction of the small and large objects such as wire, nails, is responsible for breaking intestines. Feed materials and screws, these objects down feed proteins before entering this compartment are can become lodged in they enter the small digested by inhabiting micro- the reticulum, potentially intestine. The pylorus, which organisms. The capacity of causing serious injury. The is the terminal portion of the the cecum of goats is approxi- reticulum is part of the abomasum, is characterized mately 1/4 gallon. rumen separated only by by secretions that are largely an overflow connection, mucous. The capacity of the rumino-reticular fold. the abomasum of goats is Therefore, microbial action approximately 1 gallon. Figure 2. Inside structures of rumen, also takes place in this reticulum, omasum, and abomasum of goats. Photo courtesy of G. F. W. ARCHIVEHaenlein, University of Delaware.

2 Alabama Cooperative Extension System Large Intestine: Undi- Development of the Rumination gested feed and unabsorbed Four Stomach nutrients leaving the small Rumination is defined as the intestine pass into this com- Compartments regurgitation, rechewing, and partment. The functions of When a goat kid is born, the reswallowing of rumen inges- the large intestine include rumen is small and the ab- ta. During resting, animals water absorption and further omasum is the largest of the with four stomach compart- digestion of feed materials by four stomach compartments. ments regurgitate ball-like microorganisms. The large The rumen of a goat kid is masses of fibrous and coarse intestine is comprised of the about 30 percent of the total feeds called bolus or the colon and rectum. Fecal pel- stomach area, while the ab- cud. The regurgitated cud is lets are formed in the end omasum is about 70 percent. chewed thoroughly for about portion of the spiral colon. Hence, digestion in the goat one minute then swallowed The capacity of the large kid is like that of a mono- again. Ruminant animals may intestine of goats ranges from gastric animal. In the suck- spend up to 8 hours per day 1 1/4 to 1 1/2 gallons. ling goat kid, closure of the in rumination, depending on the type of feed. This phe- Accessory Glands: The esophageal groove ensures that milk is channeled direct- nomenon affects the amount salivary glands, liver, and of feed the goat can eat. pancreas contribute to diges- ly to the abomasum instead of going through the rumen, Reducing the particle size of tion. Saliva secreted by the the feed through rechewing salivary glands is important in reticulum, and omasum. Peptic cells in the abomasum allows the material to be eas- the chewing of the cud. Bile ily accessible to the microor- produced by the liver, and of young milk-fed ruminants secrete, in addition to pep- ganisms and to pass out of stored and secreted by the the rumen. gall bladder, helps emulsify sin, the enzyme rennin. This enzyme is responsible for fat in preparation for diges- Summary tion. Enzymes secreted by forming milk curdles and the pancreas are important in digesting milk protein. Digestion in ruminant animals the small intestinal digestion When the suckling goat kid is accomplished via micro- of carbohydrates, proteins, starts to eat vegetation during bial breakdown of feed parts and fats. the first or second week after in the rumen and reticulum, birth, the rumen, reticulum, enzymatic activity in the ab- and omasum gradually devel- omasum and small intestine, op in size and function. After and microbial breakdown in approximately two months, the cecum and large intes- the four stomach compart- tine. The simple compounds Figure 3. Inside structures of rumen, ments reach their relative derived from the digestion of reticulum, omasum, and abomasum adult proportions. carbohydrates, proteins, and of deer. Photo courtesy of G. F. W. fats are absorbed mainly from Haenlein, University of Delaware. the forestomach and small ARCHIVE intestine.

Digestive System of Goats 3 References

Church, D. C. (1993). The ruminant animal: Digestive physiology and nutrition. Prospect Heights, IL: Waveland Press, Inc.

Ensminger, M. E. (2002). Sheep and goat science. 6th ed. Danville, IL: Interstate Publishers, Inc.

Gillespie, J. R. (1998). Animal science. Albany, NY: Delmar Publishers.

Jurgens, M. H. (1993). Animal feeding and nutrition. 7th ed. Dubuque, IA: Kendall/Hunt Publishing Company.

Randall, D., Burggren, W., & French, K. (2002). Eckert animal physiology: Mechanisms and adaptations. 5th ed. New York, NY: W.H. Freeman and Company.

Shapiro, L. S. (2001). Introduction to animal science. Upper Saddle River, NJ: Prentice-Hall, Inc.

Taylor, R. E. and T. G. Field. (2001). Scientific farm animal production: An introduction to animal science. 7th ed. Upper Saddle River, NJ: Prentice-Hall, Inc.

Julio E. Correa, Associate Professor and Extension Animal Scientist, Alabama A&M University ARCHIVESpecial thanks to Jean Hall Dwyer, Extension Communications Specialist, for the drawing “The digestive tract of goats.”

For more information, call your county Extension office. Look in your telephone directory under your county’s name to find the number.

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