Animal Nutrition Lecture 2024 PDF

Animal Nutrition  Learning Objectives What is nutrition? Identify the three dietary categories exhibited by animals Describe the processes of ingestion, digestion, absorption, and elimination What are the different strategies of ingestion that are observed in animals? Dist...

Animal Nutrition  Learning Objectives What is nutrition? Identify the three dietary categories exhibited by animals Describe the processes of ingestion, digestion, absorption, and elimination What are the different strategies of ingestion that are observed in animals? Distinguish between the processes of intracellular and extracellular digestion Discuss different adaptations for digestion in animals  What is an Animal? Animals are multicellular eukaryotic heterotrophs that ingest their food (eat organic material from the environment)  Nutrition Nutrition – process of acquiring and breaking apart food In general, animals fall into three dietary categories – Herbivores eat mainly plants and algae – Carnivores eat other animals – Omnivores regularly consume animals as well as plants or algae  Nutrition A diet must satisfy three needs: 1. Chemical energy for cellular processes 2. Organic building blocks for macromolecules, 3. Essential nutrients.  Nutrition A diet must satisfy three needs: 1. chemical energy (ATP) for cellular processes Animal’s activities depend on sources of chemical energy in the diet: carbohydrates, proteins, and lipids are fuel for ATP production  Cell respiration: producing energy Nutrition through the oxidation of molecules 1. Glucose 2. Glycerol 3. Amino acids Catabolic: breaks down large to small Anabolic: builds large from small  Nutrition A diet must satisfy three needs: 1. chemical energy for cellular processes 2. organic building blocks for macromolecules (sugars, proteins) Needed to grow, maintain itself, and reproduce, etc.  Nutrition A diet must satisfy three needs: 1. chemical energy for cellular processes 2. organic building blocks for macromolecules, 3. essential nutrients. Materials that an animal cannot assemble from simpler organic molecules. Need to be obtained from their diet. Include: Essential amino acids, essential fatty acids, vitamins and minerals.  Food Processing 1 INGESTION 2 DIGESTION 3 ABSORPTION 4 ELIMINATION  Ingestion Ingestion is the act of eating or feeding Strategies for extracting resources from food differ widely among animal species  Ingestion Strategies for extracting resources from food: – Suspension feeders – small food particles filtered from water  Ingestion Strategies for extracting resources from food: – Substrate/ deposit feeders – animals live in or on their food Caterpillar Feces  Ingestion Strategies for extracting resources from food: – Fluid feeders – nutrient-rich fluid is sucked  Ingestion Strategies for extracting resources from food: – Bulk feeders – relatively large pieces of food are eaten. Most animals Figure 41.5 Mechanical digestion 1 INGESTION – act of eating Chemical 2 DIGESTION digestion – process of (enzymatic breaking down hydrolysis) food 3 ABSORPTION 4 ELIMINATION  Digestion Intracellular digestion Food vacuoles engulf food by phagocytosis, and fuse with lysosomes (organelles that contain enzymes) to break down food.  Digestion Intracellular digestion – food particles are engulfed by phagocytosis; food vacuoles fuse with lysosomes  Digestion Extracellular digestion – breakdown of foods outside of cells (most animals) Allows animals to eat much larger pieces of food than can be ingested by phagocytosis Animals with a simple body plan have digestion system with single opening: gastrovascular cavity: Used in digestion and the distribution of nutrients throughout the body  Digestion Extracellular digestion – breakdown of foods outside of cells (most animals) Gastrovascular cavity 1 Digestive enzymes are released from a gland cell. 2 Enzymes break food down into small particles. 3 Food particles are engulfed and digested in food vacuoles.  Digestion Extracellular digestion – breakdown of foods outside of cells (most animals) Complex body plans have a digestive tube (called an alimentary canal) with two openings: mouth & anus. Food moves in one direction through several steps of digestion and nutrient absorption  Digestion Birds – No teeth to mechanically breakdown food – Crop to store and soften food – Two stomachs: chemical and mechanical (gizzard)  Digestion Bearded vulture Can completely digest bone Extreme acidity dissolves bones within 24 hours  Digestion Mammals Chewing aids in digestion and coats food in saliva Glands that secrete digestive juices: salivary glands, pancreas, liver, and gallbladder  Digestion Bolus of food Tongue Epiglottis Pharynx up Esophageal Glottis sphincter Epiglottis Esophageal contracted Larynx down sphincter relaxed Trachea Esophagus Glottis up and closed To To lungs stomach (a) Trachea open (b) Esophagus open Figure 41.10  Digestion Food is pushed along by peristalsis, rhythmic contractions of smooth muscles in the wall of the canal Valves called sphincters regulate the movement of material between compartments Figure 41.11 Stomach Gastric pit on the interior Epithelium surface of stomach Gastric gland Secrete juices Two components of gastric juice: 1. Hydrochloric acid (HCl) Mucous cell Secrete mucus 2. A protein-digesting enzyme, (lubricate & protect) called pepsin Chief cell Secrete pepsinogen (inactive form of pepsin) Parietal cell Produces components of HCl  Digestion Most digestion occurs in the small intestine (small diameter, but very long; >20 ft in humans) Here, pancreas, liver, and gallbladder secrete juices to aid digestion Figure 41.5 Mechanical digestion 1 INGESTION – act of eating Chemical 2 DIGESTION digestion – process of (enzymatic breaking down hydrolysis) food Nutrient molecules 3 ABSORPTION enter – uptake of nutrients body cells by body cells 4 ELIMINATION Undigested – passage of undigested material material out of body  Digestion Absorption – Most occurs in the second half of the small intestine (folds and villi increase surface area)  Digestion Alimentary canal ends with the large intestine, including the colon, cecum, and rectum Cecum: absorbs water and remaining nutrients, role in fermentation.  Digestion Alimentary canal ends with the large intestine, including the colon, cecum, and rectum Colon: Absorbs remaining water, compacts remaining materials (feces)  Adaptations for Digestion Digestive systems of vertebrates are variations on a common plan – Dental adaptations – Stomach and intestinal adaptations – Mutualistic adaptations Bonobo pika honey badger  Dental Adaptations Dental adaptations: – Homodont vs. Heterodont – most mammals have teeth with different shapes based on function (heterodont); reptile reptile teeth more or less the same (homodont) – Polyphyodont vs. Diphyodont – most vertebrates have multiple generations of teeth; most mammals have two or one generation(s) of teeth mammal only  Dental Adaptations Mammals have specialized teeth for specialized diets – heterodonty Carnivore Herbivore E.g., sharp E.g., flat teeth teeth indicate Omnivore indicate carnivory herbivory (meat-eating) (plant-eating) Key Incisors Canines Premolars Molars  Dental Adaptations Sea otters Stomach/ Intestine Adaptations Stomachs of carnivores tend to be large and Small Stomach expandable intestine Reduced cecum Cecum Colon (large intestine) Carnivore Stomach/ Intestine Adaptations Digestive system of Small intestine herbivores tend to be long Stomach to increase digestion time Elongated cecum: important role in Cecum fermenting ingested material Colon (large intestine) Herbivore  Stomach/ Intestine Adaptations Ruminants (cows, sheep, deer) Cows can spend 35-40 % of each day ruminating (chewing, regurgitate, re-chewing). 4-chambered stomachs: rumen, reticulum, omasum and the abomasum – Rumen: largest compartment with several sacs. Used in fermentation and storage – Abomasum: release gastric juices Figure 41.19 Reticulum Rumen Esophagus 3 Intestine Omasum 2 Abomasum 4 1  Mutualistic Adaptations The coexistence of humans and many bacteria involves mutualistic symbiosis Some intestinal bacteria produce vitamins; they also regulate the development of the intestinal epithelium and function of the immune system In return, bacteria get nutrients and stable host environment DNA sequencing has identified ~400 bacterial species in humans  Summary There are different methods and structures used in animal nutrition that provide them the energy and building blocks for life. Animals ingest and digest food, absorb nutrients and water, and eliminate wastes. Intracellular (within the cell) and extracellular (outside the cell) are two different methods of breading down food Animals with different diets (herbivore, carnivore, omnivore) have different adaptations (e.g., teeth, stomach(s), intestine length)