Title 02-Nutrition in Animals.pdf ✅

(vii) Small Intestine : It is a coiled tube and is about 7 metres in length. It consists of three parts, namely dueodenum, jejunum and ileum. In the small intestine the food is mixed with bile juice and pancreatic juice. These are secreted by the liver and the pancreas, respectively. Bile juice breaks down fats into fatty acids and glycerol. The pancreatic juice breaks down starch into simple sugar and proteins into amino acids. Digestion of all the components of food gets completed here and the end products are ready for absorption. Absorption of food occurs through millions of small projections in the inner walls of the part of small intestine called ileum. These projections are known as villi. The incorporation of absorbed nutrients into the cell components is called assimilation. The food that remains undigested and unabsorbed then enters the large intestine. (viii) Large intestine : It is the last organ of the digestive system. It is about 1.5 m in length. It consists of three parts, namely caecum, colon and rectum. It helps in absorbing water and in removing undigested solid wastes from the body in the form of faeces through an opening called anus. (ix) Anus : It is the last part of the alimentary canal. Its main function is to expel solid faceces out of the body. (x) Digestive Glands : (a) Salivary Glands : There are three pairs of salivary glands located in the mouth. Salivary glands secrete saliva which contains amylase enzyme. Amylase works on starch and converts it into simple sugar. (b) Liver : It is reddish brown gland and is located in the upper part of the abdomen. It secretes bile juice that is stored in gallbladder. The bile helps in breaking down fat into simpler substances. (c) Pancreas : It is a cream-coloured gland and is located just below the stomach. It secretes pancreatic juice into a small intestine. It acts on carbohydrates and protein and converts them into simpler substances. ➢ NUTRITION IN A RUMINANT A ruminant is an herbivours animal which regurgitates its food & digest it in step. For example- Cow, goats, sheep etc. The 2 steps involved in digestion of ruminants are - (1) The ruminant first eats the foods & regurgitates a semi digested food called cud. (2) The ruminant then eats the cud when at rest. This process of eating the cud is called ruminating. Ruminants have a special stomach with 4 chambers, which are as follows - • Rumen : This is the largest chamber of the stomach. It is namely used for storing food. • Reticulum : It helps in moving the food bakc to the mouth when needed. • Omasum : This is the smallest chamber of the stomach. Its main function is to absorb excess water. • Abomasum : This is a true stomach where gastric juices are secreted to help digestion. Here the food is digested just like in the human stomach. Disgestion of food in ruminants : The ruminants mostly eat grasses and leaves which are rich in cellulose, The ruminants can digest cellulose becuase celluose-digesting bacteria and protozoa are present in their stomach. MOUTH RETICULUM SALIVARY GLANDS OESOPHAGUS OMASUM ABOMASUM PANCREAS SMALL INTESTINE ANUS LARGE INTESTINE CAECUM LIVER RUMEN FIGURE : Four chambered stomach of cow (ruminant) Half-chewed grass travels from the mouth to the first chamber of the stomach called rumen where it is acted upon by bacteria and microorganism. It then goes into the reticulum from where it is returned to the mouth as cud for through chewing called rumination. It enters a third chamber called omasum. Here it is broken down into still smaller pieces. Finally, it enters the fourth chmaber called abomasum where enzymes act upon it and digestion is completed. It is finally sent to the small intestine where the absorption of the nutrients takes place.