Chapter 50 Animal Nutrition

Biology 102

Tri-County Technical College

Pendleton, SC

Diet and Energy Requirements

Fuel (chemical energy) needed for cellular respiration

Raw organic materials for biosynthesis

Essential nutrients MUST be obtained in prefabricated form

Metabolic rate is measure of overall energy needs that must be met by ingestion and digestion of food

Requirements, cont.BMR (Basal metabolism rate) defined as rate resulting from all essential physiological functions of resting person BMR is about 1300-1500 kcal/day for adult female

and 1600-1800 kcal/day for adult male

Physical activity adds to this requirementCalorie (c) or Kcalorie (C) used to measure amounts of energy in foodsFats (9.5); carbs (4.2), and proteins (4.1)ISU unit of joule where 1 c = 4.184 joules

But I am really hungry…

Undernourished person or animal is one whose diet is deficient in caloriesThis is really iffy…NCTR data now 10

years +

Malnourished person or animal is one whose diet is missing one or more essential nutrientsDepending on which nutrient, might be

more damaging than calorie deficiency

Essential Nutrients…and more

Essential amino acids are those that must be obtained in diet in prefabricated form In humans, eight are essential; can manufacture

the other 12 given precursors

Protein deficiency results when diet lacks one or more essential amino acids

Human body CANNOT store essential AAs

Deficiency retards protein synthesis

Essential Nutrients, cont.Essential fatty acids are those unsaturated fatty acids that cannot be produced by body Linoleic acid is example in humans Required to produce phospholipids for membranes Fatty acid deficiencies are rare

Vitamins are organic molecules required in diet in much smaller quantities than essential AAs/Fatty acids May serve a catalytic functionVitamin deficiencies may cause very severe effects

Essential Nutrients, cont.Water soluble versus fat soluble vitaminsIf body of animal can synthesize a certain compound, it is NOT a vitaminMinerals are inorganic nutrients required in diet in small quantities ranging from 1 mg to 2500 mg/dailySome serve structural/maintenance rolesCalcium and phosphorousOthers serve as parts of enzymes (copper) or other molecules (iron)

Water, water everywhere…

Water soluble vitamins are NOT stockpiled in body tissue so excesses excreted in urineIncludes B complex vitamins functioning as coenzymes in key metabolic processesIncludes vitamin C required for synthesis of connective tissue/antioxidantFat soluble vitamins are stockpiled in body tissues; excesses NOT excreted by body but deposited in body fatOverdoses may result in accumulation to toxic levels

Vitamins, cont.

Fat soluble vitamins are A, D, E, and K

A incorporated into visual pigments of eye

D aids in calcium absorption/bone formation

E is antioxidant for phospholipids

K required for blood clotting

Mineral mine…so to speak

Calcium found in dairy products, dark green veggies, and legumesNeeded for bone formation, blood clotting, & nerve and muscle functioningPhosphorous found in dairy products, meats, and grainsNeeded for bone/tooth formation, acid-base balance, & nucleotide synthesis

Minerals, cont.

Sulfur: proteins from many sourcesIs component of certain amino acidsPotassium: meats, dairy products, many fruits and veggies, and grainsImportant in acid-base balance, water balance, & nerve functionChlorine found in table saltAcid-base balance, formation of gastric juice, nerve function, & osmotic balance

Minerals III

Sodium found in table saltAcid-base balance, water balance, & nerve functionMagnesium: whole grains, green, leafy veggiesIs cofactor and component of ATP bioenergeticsIron: meats, eggs, legumes, whole grains, green, leafy veggiesHemoglobin, electron carrier in metabolism, & enzyme cofactor

Animal Adaptations

Animals are chemoheterotrophs (eat plants and other animals, maybe…)Herbivores eat autotrophic organisms (plants, algae, & autotrophic bacteria)Carnivores eat other animalsOmnivores eat other animals and autotrophsAnimals evolved diversity of adaptations to exploit, directly/indirectly, resources made available by autotrophs

Adaptations, cont.

Filter-feeding (suspension): sift small food particles from the water (clams/oysters; baleen whales)Substrate-feeding: live on or in food source and eat way through food (leaf miners tunnel through interior of leaves)Deposit-feeding: type of substrate-feeder that ingests partially decayed organic materials along with their substrate (earthworm ingests soil and digestive system extracts organic materials

Adaptations, III

Fluid-feeders: suck nutrient-rich fluids from a living host (aphids ingest phloem sap; leeches and mosquitoes suck blood, hummingbirds & bees ingest nectar

Bulk-feeders: eat relatively large pieces of food

I can’t believe I ate…

Digestion is process of breaking down food into small molecules body can absorb

Macromolecules are TOO large

Digestion enzymatically cleaves them into monomers that can be used by animal

Poly/Disaccharides into simple sugars

Proteins into amino acids

Fats into glycerol and fatty acids

Say what???

Gastrovascular cavity is digestive sac with single opening; functions in both digestion and nutrient distribution (Incomplete digestive tract)Most animals with simple body plans have GV cavityExtracellular digestive cavities are advantageous because allow ingestion of larger food items that can be phagocytosed and digested intracelluarlyPhylum Cnidaria (Hydra) and Phylum Platyhelminthes (planarians)

Complete Digestive TractCDT (alimentary canal) is digestive tube running between two openings; the mouth (food ingested) and anus (undigested wastes eliminated)Food moves in one direction along tubeTube can be organized into specialized regions for digestion and absorption on nutrients in stepwise fashionUnidirectional passage of food/specialization of function makes alimentary canal more efficientPhylum Nematoda, Annelida, Mollusca, Arthropoda, Echinodermata, and Chordata

Tummy growling?

Peristalsis is rhythmic smooth muscle contractions

Pushes food along alimentary tract

Alimentary tract lined with both circular and longitudinal muscle bundles

Wow, time for an Estesism

Vertebrate Digestive Tract

Teeth adapted for acquisition/initial processing of specific types of food Tear, shred, grind, and pulverize food Food chewed and mixed with secretions of

salivary glands

Esophagus is food tube connecting mouth to stomach Peristalsis moves food down esophagus Esophageal sphincter normally prevents food from

exiting stomach back into esophagus

VDT, cont.

Stomach stores food consumed Secretions kill most microorganisms and begins

digestion of proteins Processed into chyme, pyloric sphincter allows

passage into small intestine

Small intestine is major site of digestion Protein/carbs continue; fat digestion begins Absorption of nutrients begins

VDT III

Duodenum site of most digestion; jejunum and ileum responsible for ~ 90% absorption of nutrientsLarge intestine (colon) absorbs water and ionsImmense populations bacteria live in colon Vitamin K, biotin, methane, and hydrogen sulfide

Feces stored in last segment and excretedToo much water, too little water…oh yeah!!!

VDT IV

Appendix can be source of difficulty

Rectum is terminal portion of large intestineEnds at the anus

Site of fecal storage until elimination is convenient (that’s the hope)

Digestive Enzymes

Macromolecules (protein, carbs, and fats) must be broken into their monomers by hydrolytic enzymes

Hydrolysis occurs by adding water molecules

Digestive enzymes classified according to substances they hydrolyze

Digestive Enzymes, cont.

carbohydrasescarbs; proteasesprotein; peptidasespeptides; lipasesfats; nucleasesnucleic acids

Exo and endo indicate where enzyme cleaves the molecule

Example: endoprotease hydrolyzes a protein at an internal site along the polypeptide chain

Salivary Amylase

Secreted with salivaBegins starch digestion into glucose in mouthBread and crackers begin to taste “sweet” if held in mouth long enoughStarch digestion continues in duodenum where pancreatic amylases hydrolyze starch and glycogen into disaccharides

Pepsin

Major enzyme produced by stomach is endopeptidase called pepsinSecreted as zymogen (pepsinogen) by gastric glands in stomach lining (chief cells)Along with HCl of stomach, begins protein digestionSplits peptide bonds next to some AAsBegins process of “unwinding” proteins creating more surface area for other enzymes to act upon

Pancreatic Enzymes

Pancreas functions as both endocrine and exocrine glandExocrine products delivered to gut via pancreatic ductProduces host of digestive enzymes:Pancreatic amylase, lipase, nuclease, trypsin, chymotrypsin, and carboxypeptidase

Stomach tough as nails…

Stomach has pH of about 2Acidic enough to dissolve iron nailsFunction is to disrupt extracellular matrix that binds cells together in meat and plant materialAlso kills most (but not all) of bacteria that are swallowed with foodAlso produces bicarbonate buffer for neutralizing acidic chyme as exits stomach

Event Sequencing

Duodenum is first 25 cm of small intestine

>ed delivery of acid chyme to duodenum stimulates production of secretin by duodenum wall (enterogastrone) Secretin simulates bicarbonate release from

pancreas

Gallbladder stores bile produced by liver

Bile does NOT contain digestive enzymes

Sequencing, cont.

Bile does contain bile salts which emulsify fatContains pigments (byproducts of destroyed RBCs)Cholecystokinin (CCK) produced by duodenum wall stimulates pancreas to release pancreatic enzymes into small intestine & gall bladder to contract and release bile into small intestine

Sequencing III

Other enterogastrones (secreted by wall of duodenum) inhibit peristalsis in stomach This, in effect, slows food entry into small intestineMeanwhile, back at the ranch, it’s a razing stampede of mugwomps and widgets…just look at that mess!!!!

Digesting Digestion…what fun

Carbohydrate digestion begins in mouth and again in duodenum (salivary vs. pancreatic amylases Disaccharidases attached to surface of duodenal epithelium hydrolyze disaccharies into monosaccharidesEach disaccharide has its own disaccharidase

DD, cont.

Maltose/maltase; sucrose/sucrase; lactose/lactase

Occurs in epithelial brush border of small intestine

Since disaccharides are on surface of epithelim, final breakdown of carbs occurs where sugars will be absorbed

Digesting, III

Pepsin begins protein digestion in stomachPancreas secretes enteropeptidase Converts trypsinogen to trypsin

Chymotrypsin is also producedBoth specific for peptide bonds adjacent to certain AAs; break large polypeptides into smaller chains

Digesting IVCarboxypeptidase (exopeptidase) splits AAs one at time, off PP end that has free carboxyl groupLining of small intestine secretes protein digesting enzymesAminopeptidase splits one AA at time from PP end that has free amino groupDipeptidases attached to intestinal lining split small PPs

Enough of this digesting..already

Trypsin, chymotrypsin, & carboxypeptidase are secreted in inactive form by pancreasAminopeptidase, dipeptidase, & enteropeptidase are secreted by lumen of small intestinePepsin secreted by stomachTrypsin, chymotrypsin, aminopeptidase, & carboxypeptidase secreted by lumen of small intestineDipeptidases secreted by epithelium of small intestine (Brush border)

Digesting Nucleic Acids

Also involves teams of enzymesNucleases hydrolyze DNA and RNA into nucleotides Occurs in lumen of small intestine

Other hydrolytic enzymes (nucleotidases and nucleosidases) break nucleotides into nucleosides and nitrogenous bases, sugars, and phosphates

Pass the butter, please?

Fat digestion occurs ONLY in lumen of small intestineEmulsification produces many small fat droplets that have large surface area for digestionPancreatic lipase (from duodenum) hydrolyzes fats into glycerol and fatty acidsPeristalsis moves digestive enzymes-chyme mixture through the duodenum (poly into mono)

Bitter as bile…

Bile is produced by liver and store in gall bladderActs as detergent and aids in digestion and absorption of fatsAlso contains pigments that are by-products of red blood cell destruction in the liver“Funny tasting chicken liver…you bet!!!!

And finally, brethren…Most nutrient absorption occurs in jejunum and ileum of small intestineLarge folds increase surface available for absorptionMany villi (projections from surface) increase SA of small intestineVilli covered with microscopic microvilli which > surface area for contact with contents and absorption (300 m2)Most water reabsorbed in large intestine (colon)

Call it like it is…

Feces is wastes of the digestive tract moved through tract by peristalsisIntestinal bacteria live on organic material in feces Produce some vitamin K (mutualism)

Feces may contain abundance of saltsStored in rectum and passes through 2 sphincters; 1 voluntary and 1 involuntary to anus for eliminationLiterally…the end