Chapter 41 Animal Nutrition Animals can be Carnivores Omnivores and Herbivores when it comes to nutrition Most animals are opportunistic feeders eating foods outside their standard diet when their usual foods aren t available 41 1 AN ANIMAL S DIET MUST SUPPLY CHEMICAL ENERGY ORGANIC MOLECULES AN ESSENTIAL NUTRIENTS An adequate diet must satisfy 3 nutritional needs chemical energy for cellular processes organic building blocks for macromolecules and essential nutrients The activities of cells tissues organs and the whole animal depend on sources of chemical energy in the diet which is used to produce ATP and power processes Animals ingest and digest nutrients including carbohydrates proteins and lipids for use in cellular respiration and energy storage Animals also need the supply of raw materials for biosynthesis complex molecules it needs to grow maintain it self and reproduce Animals obtain organic carbon through sugar and also need organic nitrogen to construct organic molecules ESSENTIAL NUTRIENTS Some cellular processes require materials that an animal cannot assemble from simpler organic precursors These are called ESSENTIAL NUTRIENTS which are obtained from an animals diet This includes amino acids fatty acids vitamins and minerals The key roles nutrients play in cell is acting as substrates of enzymes as coenzymes and as cofactors in biosynthetic reactions Needs for particular nutrients vary among species Essential Amino Acids Animals need 20 amino acids to make proteins Animals have enzymes to make about half of these as long as they obtain sulfur and organic nitrogen The other remaining amino acids must be obtained from food These are ESSENTIAL AMINO ACIDS Animal products such as Cheese Meat and Eggs provide all essential amino acids while Plant products don t Essential Fatty Acids Animals require fatty acids to synthesize cellular components such as membrane phospholipids signaling molecules and storage fats Animals can synthesize many fatty acids but cannot form ones with double bonds due to a lack of enzymes Therefore the ones that cannot be produced are obtained through diet and are called ESSENTIAL FATTY ACIDS Vitamins According to Albert Szent Gyorgyi discoverer of Vitamin C a vitamin is a substance that makes you ill if you don t eat it VITAMINS ARE ORGANIC MOLECULES THAT ARE REQUIRED IN THE DIET IN VERY SMALL AMOUNTS Vitamins can either be water soluble or fat soluble B vitamins act as coenzymes and are water soluble C vitamins are required for the production of connective tissue and are also water soluble Vitamin A and Vitamin D are fat soluble Vitamin A is incorporated into visual pigments while Vitamin D aids in calcium absorption and bone formation Table 41 1 shows complete list of Vitamins Minerals Dietary Minerals are inorganic nutrients such as Iron and Sulfur that are usually required in small amounts Minerals have diverse functions in animal physiology Some are assembled into the structure of proteins e g Iron is incorporated into oxygen carrier hemoglobin and some enzymes Sodium Potassium and Chloride are important in the functioning of nerves muscles and maintain osmotic balance between cells and surrounding body fluid Vertebrates require calcium and phosphorous for building and maintain bone Ingesting to many minerals can disrupt heath and homeotic balance excess salt lead to high blood pressure Table 41 2 Show complete list of Minerals DIETARY DEFICIENCIES A diet that lacks one or more essential nutrients or consistently supplies less chemical energy than the body requires results in Malnutrition Malnutrition can result from any type of dietary deficiency Deficiencies in Essential Nutrients Insufficient intake of essential nutrients can cause deformities disease and even death For example animals consuming plants that lack phosphorous may have very weak bones A diet that provides insufficient amounts of essential amino acids causes protein deficiency most common in humans Also children can suffer deficiencies when they switch from breast milk to adult foods too early Undernutrition A diet that fails to provide adequate sources of chemical energy results in undernutrition When this occurs the body uses up stored carbohydrates and fat and breaks down proteins for fuel muscles get broken down If energy intake is less than energy expenditures the organism may die ASSESING NUTRITIONAL NEEDS It is difficult to asses the nutritional needs of humans because they are genetically diverse and have diverse lifestyles However it was discovered that children born to women of lower socioeconomic status had neural tube defects which is due to malnutrition among these women Vitamin supplementation however greatly reduced this 41 2 THE MAIN STAGES OF FOOD PROCESSING ARE INGESTION DIGESTION ABSORPTION AND ELIMINATION Food processing can be divided into 4 distinct stages Ingestion Eating Or Feeding Digestion Food is broken down into molecules o Mechanical breaks food down into smaller pieces which increases surface area chewing o Chemical Digestion necessary to make proteins carbs nucleic acids fats and phospholipids available to the organism large molecules cannot pass through membranes and pass into cells Broken down molecules can be build into larger molecules addition of water enzymatic hydrolysis Making larger molecules done through dehydration synthesis o Absorption animal cells absorb small molecules amino acids sugars o Elimination undigested material passes out DIGESTIVE COMPARTMENTS The food that animals eat is made up of the same biological materials that make up our body Our bodies avoid self digestion through an evolutionary adaption that allow us to digest our food in specialized intracellular or extracellular compartments 4 MAIN FEEDING MECHANISMS OF ANIMALS Filter Feeding straining small organism or food particles from surroundings Substrate Feeding animals live in or on food Fluid Feeding suck nutrient rich fluid from host Bulk Feeding eat relatively large pieces of food Adaptations include tentacles pincers claws venomous fangs jaws and teeth Intracellular Digestion Food vacuoles cellular organelles in which hydrolytic enzymes break down food are the simplest digestive compartments The hydrolysis of food inside vacuoles is called intracellular digestion and begins after a cell engulfs solid food through PHAGOCYTOSIS or liquid food through PINOCYTOSIS Food vacuoles that are newly formed fuse with lysosomes with the lysosomes providing hydrolytic