Animal Nutrition Notes

Animal Nutrition

  • Figure 41.1 Herring gull eating a sea star illustrates nutrient extraction and tissue composition similarities.

  • Compartmentalization in digestion protects body tissues.

  • Nutrients are transported through epithelial cells and absorbed into the bloodstream.

  • Digestive secretions break down food, releasing nutrients.

  • Bloodstream carries secretions that promote digestion.
    = Diagram shows food waste going to the bloodstream, uptake of nutrients and water in the blood, protective secretions, nutrients transported, and digestive secretions.

Key Concepts

  • An animal's diet must supply chemical energy, organic building blocks, and essential nutrients.

  • Food processing involves ingestion, digestion, absorption, and elimination.

  • Organs specialized for sequential stages of food processing form the mammalian digestive system.

  • Evolutionary adaptations of vertebrate digestive systems correlate with diet.

  • Feedback circuits regulate digestion, energy storage, and appetite.

Study Tip

  • Make flowchart of digestion in the human alimentary canal, tracking the overall effect and location of each step.

    • Start of flowchart:

      1. Break food into smaller pieces and mix with saliva (oral cavity).

      2. Transfer boluses of food to stomach (esophagus).

      3. Denature proteins in food (stomach).

Essential Amino Acids

  • Organisms need 20 amino acids for proteins; plants and microorganisms can produce all 20.

  • Animals can synthesize about half if their diet includes sulfur and organic nitrogen.

  • Essential amino acids must be obtained from food.

  • Adult humans need eight: isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine (infants also need histidine).

  • Animal products (meat, eggs, cheese) are "complete" proteins with all essential amino acids.

  • Most plant proteins are "incomplete," lacking one or more essential amino acids.

  • Vegetarians can obtain all essential amino acids through a varied diet.

  • Corn is deficient in tryptophan and lysine, while beans lack methionine.

Essential Fatty Acids

  • Animals need fatty acids for cellular components like phospholipids, signaling molecules, and storage fats.

  • They can synthesize many, but not all, fatty acids and must obtain essential fatty acids from diet.

  • Mammals require linoleic acid.

  • Animals obtain ample essential fatty acids from seeds, grains, and vegetables.

Concept 41.1

  • An animal’s diet must supply chemical energy, organic building blocks, and essential nutrients.

  • All animals eat other organisms for energy and organic molecules (dead or alive, piecemeal or whole).

  • Adequate diet needs: chemical energy, organic building blocks, and essential nutrients.

  • Nutrition: the process by which an animal takes in and makes use of food to meet these needs.

  • Chemical energy from diet produces ATP for cellular processes (DNA replication, cell division, vision, flight).

  • Animals ingest and digest carbohydrates, proteins, and lipids for cellular respiration and energy storage.

  • Raw materials for biosynthesis: organic carbon (sugar) and organic nitrogen (protein).

  • Essential Nutrients: Substances that an animal requires but cannot assemble from simple organic molecules.

  • Essential nutrients include certain amino acids and fatty acids, as well as vitamins and minerals.

  • Key functions of essential nutrients include serving as substrates of enzymes, as coenzymes, and as cofactors in biosynthetic reactions (Figure 41.2).

Figure 41.2

Roles of essential nutrients. This example of a biosynthetic reaction illustrates some common functions for essential nutrients. Example of a biosynthetic reaction where linoleic acid is converted to g-linoleic acid by the enzyme fatty acid desaturase.
Linoleic acid \longrightarrow i-Linoleic acid

  • Enzyme: Fatty acid desaturase.

  • Essential Amino Acids (subunits of polypeptide)

  • Vitamin (source of coenzyme NADH)

  • Essential Fatty Acid (substrate of enzyme)

  • Mineral (cofactor) Iron

Vitamins

  • Vitamins: organic molecules required in small amounts (0.01-100 mg per day).

  • 13 vitamins for humans vary in chemical properties and function.

  • Vitamin B2: water-soluble, converted to FAD, a coenzyme used in metabolic processes, including cellular respiration.

  • Vitamin C: water-soluble, required for connective tissue production.

  • Fat-soluble vitamins (A and D).

  • Vitamin A: incorporated into visual pigments.

  • Vitamin D: aids in calcium absorption and bone formation synthesized when skin exposed to sunlight.

  • Vitamin supplements at RDAs are reasonable for imbalanced diets, but massive doses may not be safe.

  • Excess water-soluble vitamins are usually harmless because they are typically excreted in urine.

  • Excess fat-soluble vitamins can accumulate to toxic levels in body fat.

Minerals

  • Dietary minerals are inorganic nutrients (iron, sulfur) usually required in small amounts (less than 1 mg to 2,500 mg per day).

  • Some minerals assemble into protein structures.

  • Iron is incorporated into hemoglobin (oxygen carrier) and enzymes (see Figure 41.2).

  • Sodium, potassium, and chloride: important in nerve/muscle function and osmotic balance.

  • Iodine: incorporated into thyroid hormone (regulates metabolic rate).

  • Calcium and phosphorus: building and maintaining bone.

  • Excess of some minerals can cause health problems.

  • Excess sodium can contribute to high blood pressure (problem in the U.S. where people consume 20x RDA of sodium).

  • Processed foods often contain large amounts of sodium chloride, even if they do not taste salty.

Variation in Diet

  • Despite shared nutritional needs, animals have diverse diets.

  • Herbivores: dine mainly on plants or algae.

  • Carnivores: mostly eat other animals.

  • Omnivores: regularly consume animals as well as plants or algae.

  • Most animals are opportunistic feeders, broadening their diet when usual foods aren’t available.

  • Microorganisms are unavoidable "supplement" in every animal’s diet.

Dietary Deficiencies

  • Diet lacks essential nutrients or consistently supplies less chemical energy than required = malnutrition.

  • Insufficient intake of essential nutrients can cause deformities, disease, and death.

  • Deer and herbivores can develop fragile bones if plants consumed grew in phosphorus-deficient soil.

  • Some grazing animals obtain missing nutrients by consuming concentrated sources of salt or other minerals (Figure 41.3).

  • Some birds supplement their diet with snail shells, while certain tortoises obtain minerals from stones they ingest.

  • Insufficient amounts of one or more essential amino acids cause protein deficiency (most common type of malnutrition among humans).

  • Children may have impaired physical and mental development if their diet shifts entirely from breast milk to foods with relatively little protein, such as rice.

Undernourishment

  • Malnutrition can also be caused by a diet that fails to provide enough chemical energy.

  • The body first uses up stored carbohydrates and fat, then breaks down its own proteins for fuel, which causes muscles to shrink and the brain may become protein-deficient.

  • Animal will eventually die if energy intake remains less than energy expenditures.

  • Some of the damage from severe undernourishment may be irreversible, even if a seriously undernourished animal survives drought, war, or other crisis severely disrupts the food supply.

  • Anorexia nervosa involves weight loss to a level that is unhealthy for the individual’s age and height and may be related to a distorted body image.

Assessing Nutritional Needs

  • Determining the ideal diet is an important but difficult problem because

    • Humans are genetically diverse, live in varied settings, and ethical concerns present barrier

  • Many insights come from epidemiology: the study of human health and disease at the population level.

  • Vitamin supplementation greatly reduced the risk of neural tube defects, folic acid responsible, confirmed by other researchers.

  • United States in 1998 required folic acid added to enriched grain products.

  • Thus, a simple dietary change such as folic acid supplementation may be among the greatest contributors to human health.

Concept 41.2

  • Food processing involves ingestion, digestion, absorption, and elimination.

  • Ingestion: the act of eating or feeding. Four categories:
    1. Filter feeding
    2. Substrate feeding
    3. Bulk feeding
    4. Fluid feeding

Fluid Feeding

Fluid feeders suck nutrient-rich fluid from a living host. Example: is a tsetse fly has pierced the skin of its human host with hollow needlelike mouthparts and is consuming a blood meal.

Bulk Feeding

Most animals, including humans, are bulk feeders, which eat relatively large pieces of food. Example: rock python is beginning to ingest a gazelle it has captured and killed.

Filter Feeding

Many aquatic animals are filter feeders, which strain small organisms or food particles from the surrounding medium. Example: Humpback whale

Substrate Feeding

Substrate feeders are animals that live in or on their food source. Example: leaf minor caterpillar

Digestion

  • Second stage of food processing, broken down into molecules small enough for the body to absorb.

  • Mechanical digestion, such as chewing or grinding, breaks food into smaller pieces, increasing surface area.

  • Then undergo chemical digestion, which cleaves large molecules into smaller components.

  • Animals cannot directly use the proteins, carbohydrates, nucleic acids, fats, and phospholipids in food, because these molecules are too large to pass through cell membranes and also are not all identical to those the animal needs for its particular tissues and functions.

  • Enzyme-catalyzed synthesis of a fat or macromolecule links together smaller components, releasing a molecule of water for each new covalent bond formed. Chemical breakdown by digestive enzymes reverses this process, breaking bonds through the addition of water. This splitting process is called enzymatic hydrolysis.

Sucrose (C{12}H{22}O{11})+H2O \longrightarrow Glucose (C6H{12}O6 ) + Fructose (C6H{12}O6 )

Digestive Compartments

  • Digestive enzymes hydrolyze biological materials that make up animals themselves.
    Compartmentalization allows animals to digest food without digesting their own cells/tissues.
    Intracellular Digestion: simplest digestive compartments are food vacuoles, cellular organelles in which hydrolytic enzymes break down food. Food vacuoles fuse with lysosomes.
    Extracellular Digestion: breakdown of food in compartments that are continuous with outside of animal's body, enabling an animal to devour much larger pieces of food than can be ingested by phagocytosis.

Mammals

  • Mammals have a number of accessory glands such as salivary glands, the pancreas, the liver, and the gallbladder

  • The Oral Cavity, Pharynx, and Esophagus
    The oral cavity is where processing begins, teeth break down food, and saliva is released.
    Saliva: contains mucus, buffers, and antimicrobal agents
    Tongue: Aids digestive process
    Pharynx: throat region
    Esophagus: Food is pushed by peristalsis
    Digestion in the Stomach:
    The stomach has major roles in digestion. The first is storage and the second is when gastric juice and food create chyme.
    Chemical Digestion in the Stomach: Two components in gastric juice help liquefy food in the stomach. First, HCl is disrupted. The second component is pepsin.

Concept 41.2

  • Mammals, a number of accessory glands support food processing.

  • Stepwise function, we'll follow in a human

  • Saliva is a complex mixture has vital function, one component mucus viscose mixture of water

  • Tongue aids digestive processes by evaluating ingested material

  • Swallowing must be carefully choreographed to keep food and liquids from entering the trachea

  • Within the esophagus, food is pushed along by peristalsis alternating waves.

  • The stomach has two major roles in digestion
    1. Storage
    2. To process food into suspension
    Two component of gastric Juice help liquefy food in the stomach
    1. HCl
    2. Pepsin
    Two cells in the gland of the stomach produce component into gastric juice
    1. Parietal
    2. Chief cells
    Why does HCl and pepsin not eat though lining of stomach ?
    First, mucus secreted by cells
    Second, cell division adds new epithelial layer every three days

Digestion in small intestine

  • Mostly enzymatic hydrolysis of macromolecules from food occurs in the small intestine

  • First 25 cm form Duodenum, chyme from stomach mixes with digestive juices from pancreas, liver, and gallbladder, as well as from gland cells of the intestinal wall itself.

  • The presence of the acids in bile salts also have solubility for lipids (hydrophobic) and other surfaces How is this beneficial, By using emullsifiers Fats present challenge for digestion
    Absorption in the Small Intestine:
    With digestion largely complete, the contents of the duodenum move into the small intestine . There nutrient absorption occurs across the intestine. Large folds enricle the intestine and contains studed with projections

Intestine Cells

  • Vein carrying blood to liver

  • Blood capillaries

  • Epithelial cells Lymph vessel Lacteal Microvilli of brush border

  • Muscles Layers
    Water-soluble nutrients, such as amino acids and sugars, enter the bloodstream, whereas fats are transported to the lymphatic system

Processing in Large Intestine

  • Completes the recovery of water and removes material begins, this happens in colon, as these wastes pass to the end of the alimentary canal to the

  • Rectum where feces are stored before elimination the end result is undigested material, such as cellulose fiber

Figure 41.15

Dentition and diet. Herbivores, such as horses and deer, usually have premolars and molars with broad, ridged surfaces that grind tough plant material. The incisors and canines are generally modified for biting off pieces of vegetation. In some herbivores, canines are absent

Carnivore

Carnivores, such as members of the dog and cat families, generally have large, pointed incisors and canines that can be used to kill prey and rip or cut away pieces of flesh. The jagged premolars and molars crush and shred food.

Herbivore

Herbivores, such as horses and deer, usually have premolars and molars with broad, ridged surfaces that grind tough plant material. The incisors and canines are generally modified for biting off pieces of vegetation. In some herbivores, canines are absent

Omnivore

  • As omnivores, humans are adapted to eating both plants and meat. Adults have 32 teeth. From front to back along either side of the mouth are four bladelike incisors for biting, a pair of pointed canines for tearing, four premolars for grinding, and six molars for crushing

Stomach

  • Stomach and Intestinal Adaptations Evolutionary adaptations to differences in diet are sometimes apparent as variations in the dimensions of digestive organs. A large expandable stomachs are common in carnivorous vertebrates, which may wait a long time between meals and must eat as much as they can when they do catch prey.

Mutualistic Adaptation

An estimated 10–100 trillion bacteria live in the human digestive system. The coexistence of humans and many intestinal bacteria is an example of mutualism, an interac- tion between two species that benefits both of them. The gut's microbiome, which scientists are using a DNA sequencing approach based on the polymerase chain reaction.

Vertebrate

Vertebrate mutualistic relationships with micrograms also help these vertebrates. They get such an arrangement these animals house there symbiont is also housed in a large cecum. Rabbits and some rodents are also part of the mutualistic community. Adaptations are important in herbivores and other animals alike expand the nutrition sources that are available to animals

Ruminant Digestion

  • The Stomach of a cow, has 4 chambers.

    • (1) The Chew food enters rumen and reticulum, microorganisms digests cellulose

    • (2) The cow regurgitates and rechews from the reticulum to break down fibers

    • (3) Cud passes to omasum

    • (4) The cow obtains by digestion 4

Regulation of Digestion

Regulated at multiple level and depend no matter how simple or large the digestive system the animals used. Some animals face time to time between meals. There is also another system that is used through throughout the bloodstream

Hormones

*Hormone action in coordination with the nervous system and what the actions that happen (Gastrin, CCK ,Liver, Stomach, Pancreas)
Gastrin: which secreted , CCK Hormone(released by duodenum)
, Gastric Juices Key : + = Stimlation , - = inhibition
Secretin ,Bile ,HCo, Enzymes .
*The hormones are then transported through the bloodsteam.
Regulation of Energy Storage begins at the liver the synthesis and breakdown
After you eat food is absourbed the hormones from the pancrea secrete in the blood insulin for uptake of fuels and glucagon for expending stored energy*