Animal, Plant & Soil Science

1. Animal, Plant & Soil Science Lesson C3-2 Animal Digestion

2. Interest Approach • Show the students a transparency of one of the digestive systems. Ask the students, “What is this?” When you have gotten the correct answer, ask the students, “Why is it important for livestock producers to understand this?” Lead discussion to Objective 1 of the lesson.

3. Objectives • Identify the various types of digestive systems found in animals. • Identify the major parts of the digestive system and describe their functions.

4. abomasum absorption amino acids anus avian digestive system bile cecum chyme crop cud digestion digestive system enzymes eructated feces gizzard Terms

5. intestinal juice monogastric digestive system omasum organs pancreatic amylase pancreatic juice pepsin pseudo-ruminant digestive system reticulum rumen ruminant ruminant digestive system Terms

6. rumination salivary amylase salivary maltase stomach trypsin villi Terms

7. What are the various types of digestive systems found in animals? • Knowledge of the different types of digestive systems is critical in selecting the proper feeds for livestock. • Understanding the chemical and physical changes that occur during the digestive process leads to more efficient livestock feeding. • Digestion is the process of breaking down food into simple substances that can be absorbed by the body. • Absorption is the process of taking the digested parts of food into the bloodstream.

8. What are the various types of digestive systems found in animals? • The digestive system consists of the parts of the body involved in chewing and digesting food. • This system also moves the digested food through the animal’s body and absorbs the products of digestion. • Different species of animals are able to digest certain types of feeds better than others. • This difference occurs because of the various types of digestive systems found in animals. • There are four basic types of digestive systems: monogastric (simple), ruminant (polygastric), pseudo-ruminant, and avian.

9. What are the various types of digestive systems found in animals? • A. The monogastric digestive system, or simple digestive system, contains a single-chambered stomach and is the type found in humans, swine, dogs, and cats. • The stomach is a muscular organ that stores ingested food and moves it into the small intestine.

10. What are the various types of digestive systems found in animals? • The stomach secretes acid that has a low pH of 1.5 to 2.5. • The low pH destroys most bacteria and begins to break down the food materials. • Animals with this type of digestive system are better adapted to the use of concentrated feeds, such as grains, than to the use of large quantities of roughages.

11. What are the various types of digestive systems found in animals?

12. What are the various types of digestive systems found in animals? • B. The ruminant digestive system, or polygastric digestive system, contains one large stomach divided into four compartments and is the type found in cattle, sheep, and goats. • An animal with this kind of digestive system is called a ruminant. • Due to the complexity of its digestive system, a ruminant can make good use of roughages. • Forty-four percent of the roughages fed are digested. • The compartments of the stomach, in the order of digestion, are rumen, reticulum, omasum, and abomasum.

14. What are the various types of digestive systems found in animals? • 1. The rumen is the largest section of the stomach and the first compartment that the food enters. • It accounts for approximately 60 percent of the stomach. • The rumen contains bacteria and other microbes that promote fermentation. • The rumen is designed so that food can be ingested, eructated (belched up), chewed, and then swallowed again.

15. What are the various types of digestive systems found in animals? • 2. The reticulum is the second segment of the stomach. • It is sometimes considered an extension of the rumen. • The reticulum has honeycomb-like ridges. • It aids in keeping the food in the rumen mixed with water and saliva until it is the right consistency. • Once the right consistency is reached, the mixture can pass on into the lower digestive tract.

16. What are the various types of digestive systems found in animals? • 3. The omasum is a small compartment that is the main sight for water absorption. • The particles are squeezed and dehydrated, as well as sorted. • The compartment acts as a filter for the abomasum.

17. What are the various types of digestive systems found in animals? • 4. The abomasum, or “true stomach,” is the site of digestion. • It secretes gastric juices consisting of hydrochloric acid and pepsin. • These juices kill and then digest the microbes that have passed with the food materials from the rumen. • The abomasum is similar to the stomach in a monogastric animal.

18. What are the various types of digestive systems found in animals? • C. The pseudo-ruminant digestive system is the type found in animals that eat large amounts of roughages but do not have stomachs with several compartments. • This type of digestive system performs some of the same functions as the type found in ruminants.

19. What are the various types of digestive systems found in animals? • A pseudo-ruminant can utilize large amounts of roughages because of its greatly enlarged cecum and large intestine. • Such an animal often eats forages as well as grains and other concentrated feeds. • Examples of pseudo-ruminants are horses, rabbits, guinea pigs, and hamsters.

21. What are the various types of digestive systems found in animals? • D. The avian digestive system is the type found in poultry. • This system differs greatly from any other type. • Since a bird has no teeth, no chewing is involved. • The esophagus empties directly into the crop.

22. What are the various types of digestive systems found in animals? • The crop is where the food is stored and soaked. • From the crop, the food makes its way to the gizzard. • The gizzard is a very muscular organ, which normally contains stones or grit that grinds the food. • Digestion in the avian system is very rapid.

24. What are the major parts of the digestive system and their functions? • The digestive system is made up of a number of organs, which are parts that perform specialized functions. • The digestive system begins at the mouth, where food enters the body, and continues to the anus, where undigested material exits the body. • The digestive systems of most livestock are very similar in terms of the organs they contain. • Some of the major parts of a digestive system and their functions are:

25. What are the major parts of the digestive system and their functions? • A. Mouth and esophagus—The chewing action of the mouth and teeth breaks, cuts, and tears up the food. • This increases the surface area of the food particles and aids in the swallowing process. • Saliva not only stimulates the taste of the food but also contains the enzymes salivary amylase and salivary maltase.

26. What are the major parts of the digestive system and their functions? • Enzymes are organic catalysts that speed up the digestive process. • Salivary amylase changes starch to maltose, or malt sugar. • Salivary maltase changes maltose to glucose. • Chewed food passes from the mouth to the stomach through a muscular tube called the esophagus.

27. What are the major parts of the digestive system and their functions? • B. Monogastric stomach—When food enters the stomach of a monogastric animal, gastric juices begin to flow. • The fluids come from glands in the wall of the stomach. • The juices contain from 0.2 to 0.5 percent hydrochloric acid. • This acid stops the action of the amylase from the mouth.

28. What are the major parts of the digestive system and their functions? • The gastric juices also contain the enzymes pepsin, rennin, and gastric lipase. • Pepsin breaks the proteins in the food into proteoses and peptones. • The muscular walls of the stomach churn and squeeze the food. • Liquids are pushed on into the small intestine. • The gastric juices then act on the solids that remain in the stomach.

29. What are the major parts of the digestive system and their functions? • C. Ruminant stomach—The four parts of the ruminant stomach are rumen, reticulum, omasum, and abomasum. • A ruminant typically eats rapidly. • It does not chew much of its food before swallowing. • The solid part of food goes into the rumen.

30. What are the major parts of the digestive system and their functions? • The liquid part goes into the reticulum, then into the omasum, and on into the abomasum. • In the rumen, the solid food is mixed and partially broken down by bacteria. • When the rumen is full, the animal lies down. • The food is then forced back into the mouth, and rumination occurs. • Rumination is the process of chewing the cud. • The cud is a ball-like mass of food brought up from the stomach to be rechewed.

31. What are the major parts of the digestive system and their functions? • On average, cattle chew their cuds about six to eight times per day. • Five to seven hours each day are spent in rumination. • The rumen and the reticulum contain millions of bacteria and protozoa. • It is the bacterial action in the rumen that allows a ruminant to use large amounts of roughage. • The bacteria can change low-quality protein into the amino acids needed by the animal.

32. What are the major parts of the digestive system and their functions? • Amino acids are compounds that contain carbon, hydrogen, oxygen, and nitrogen. • They are essential for growth and maintenance of cells. • Bacteria also produce many of the vitamins needed by the animal.

33. What are the major parts of the digestive system and their functions? • D. Small intestine—The partly digested food that leaves the stomach enters the small intestine as an acidic, semifluid, gray, pulpy mass. • This material is called chyme. • In the small intestine, the chyme is mixed with three digestive juices: pancreatic juice, bile, and intestinal juice.

34. What are the major parts of the digestive system and their functions? • 1. Pancreatic juice, secreted by the pancreas, contains the enzymes trypsin, pancreatic amylase, pancreatic lipase, and maltase. • Trypsin breaks down proteins not broken down by pepsin. • Some of the proteoses and peptones are broken down by trypsin into peptides. • Proteoses, peptones, and peptides are combinations of amino acids.

35. What are the major parts of the digestive system and their functions? • Proteoses are the most complex compounds, and peptides are the simplest. • Pancreatic amylase changes starch in the food into maltose. • Sugar and maltose are broken down even further by maltase. • They are then changed into a simple sugar called glucose. • Lipase works on fats in the food, changing them into fatty acids and glycerol.

36. What are the major parts of the digestive system and their functions? • 2. Bile is a yellowish-green, alkaline, bitter liquid produced in the liver. • Bile is stored in the gallbladder in all animals except the horse. • Bile aids in the digestion of fats and fatty acids. • It also aids in the action of the enzyme lipase.

37. What are the major parts of the digestive system and their functions? • 3. Glands in the walls of the small intestine produce intestinal juice. • Intestinal juice is a fluid that contains peptidase, sucrase, maltase, and lactase, all enzymes used in digestion. • Proteoses and peptones are broken down by peptidase into amino acids. • Starches and sugars are broken down by sucrase, maltase, and lactase into the simple sugars glucose, fructose, and galactose.

38. What are the major parts of the digestive system and their functions? • E. Cecum—The cecum, or “blind gut,” is found where the small intestine joins the large intestine. • It has little function in most animals. • In a pseudo-ruminant, the roughages consumed are digested by the bacterial action in the cecum.

39. What are the major parts of the digestive system and their functions? • F. Large intestine—The main function of this organ is to absorb water. • Material not digested and absorbed in the small intestine passes into the large intestine. • The key to absorption in the large intestine is the small fingerlike projections on the walls, called villi.

40. What are the major parts of the digestive system and their functions? • Food materials not digested or absorbed are called feces. • These materials are moved through the large intestine by muscles in the intestinal walls. • The undigested part of food is passed out of the body through the anus, the opening at the end of the large intestine.

41. What are the various types of digestive systems found in animals? What are the major parts of the digestive system and their functions? Review