ANSC 221 exam 2

Mouth

beginning of digestion, mechanical breakdown and saliva secretion

Lips

prehension, most important in horses, least in poultry

Teeth

mastication, grind and crush feed

Tongue

swallowing and taste, moves feed to esophagus

Esophagus

tube connecting mouth to stomach, transports feed

Stomach

secretes acid and enzymes, site of protein digestion

Proventriculus

glandular stomach in birds, secretes enzymes

Rumen

fermentation vat, microbes digest fiber and synthesize nutrients

Reticulum

hardware stomach, traps foreign objects

Omasum

many plies, absorbs water and nutrients

Abomasum

true stomach, secretes enzymes and acid

Small intestine

main site of nutrient absorption

Pyloric valve

controls flow from stomach to duodenum

Duodenum

first part of small intestine, receives bile and pancreatic juice

Jejunum

middle section of small intestine, absorption

Ileum

last section of small intestine, absorption

Cecum

blind pouch, fermentation in nonruminants

Colon

part of large intestine, water absorption

Large intestine

storage and water absorption

Rectum

final section of GI tract, feces expelled

Anus

exit point for waste

Cloaca

common exit for digestive and urinary tracts in birds

Crop

storage pouch in birds

Cecae

paired fermentation sacs in birds

Liver

produces bile, metabolizes nutrients

Gall bladder

stores bile

Pancreas

secretes digestive enzymes and hormones

Salivary amylase

breaks down starch in mouth

Bicarbonate

buffers rumen pH, secreted in saliva and pancreas

HCl

activates pepsinogen, lowers stomach pH

Mucin

protects stomach lining

Rennin

coagulates milk protein in young animals

Pepsinogen

inactive form of pepsin

Pepsin

digests protein in stomach

Gastric lipase

digests fat in stomach

Intrinsic factor

helps absorb vitamin B12

Carboxypeptidase

digests protein, secreted by pancreas

Trypsin

digests protein, activated in small intestine

Chymotrypsin

digests protein, secreted by pancreas

Pancreatic lipase

digests fat in small intestine

Pancreatic amylase

digests starch in small intestine

Aminopeptidase

digests protein fragments in small intestine

Sucrase

digests sucrose

Maltase

digests maltose

Lactase

digests lactose

Nucleotidases

digest nucleotides

Nucleosidases

digest nucleosides

Gastrin

stimulates acid secretion in stomach

Secretin

stimulates pancreatic secretion of water and electrolytes

Cholecystokinin

stimulates gall bladder contraction and pancreatic enzymes

GIP

inhibits gastric secretion and motility

Enterocrinin

stimulates intestinal secretion

Protein digestibility

percentage of protein absorbed from feed

Nitrogen balance

nitrogen intake minus losses in feces and urine

Nitrogen retention

nitrogen retained in body tissues

Biological value

percentage of digested protein retained by body

True digestibility

accounts for metabolic fecal nitrogen

Apparent digestibility

does not account for metabolic losses

Endogenous

originating from within the body

Gross energy

total energy in feed

Digestible energy

gross energy minus fecal energy

Metabolizable energy

digestible energy minus urinary and gas energy

Net energy

metabolizable energy minus heat increment

Heat increment

energy lost as heat during digestion and metabolism

TDN

total digestible nutrients, an energy index

NPN

non-protein nitrogen, usable by ruminants

Urea

example of NPN, used in ruminant diets

Protein evaluation in cattle

focus on degradable and undegradable intake protein

Protein evaluation in hogs

focus on digestibility and amino acid balance

Soybean meal

high lysine, most common protein feed

Cottonseed meal

contains gossypol, lower protein qualit