Animal Nutrition Exam 1

what is nutrition?

The interrelated steps by which a living organism assimilates food and uses it for growth, tissue repair and replacement, or elaboration of products

what is a nutrient?

A substance that provides the nourishment essential for growth and the maintenance of life

what are the 6 main nutrients?

carbohydrates, proteins, fats, vitamins, minerals, water

difference between minerals and vitamins

vitamins = organic compounds, specific role in metabolism

minerals = inorganic components of plant and animal tissues

What is the primary function of enzymes?

To act as catalysts in metabolic reactions.

What do enzymes do to chemical reactions?

They accelerate chemical reactions.

What happens to enzymes after a reaction?

They return to their normal form post reaction.

Are enzymes substrate specific?

Yes, enzymes are substrate specific.

What do enzymes work with to shuttle substrates?

Cofactors and coenzymes.

What are hormones?

Substances that are produced in one tissue and transported to a target tissue.

How is the production and release of hormones regulated?

By positive or negative feedback.

digestion

The preparation of food for absorption, either mechanical, chemical, enzymatic

absorption

The process by which nutrient molecules pass through the wall of the digestive system into the blood or lymph systems

metabolism

The summation of biochemical processes in living tissue

catabolism

breakdown or oxidation of fuels

anabolism

synthetic reactions that build up tissues

carnivores

short uncomplicated large intestine, highly digestible diet

herbivores/omnivores

More complicated Gastrointestinal tracts (GI), Diet varies in digestibility, Modified to improve utilization of plant tissue

monogastrics

single compartment stomach, auto enzymatic, one long tube

ruminants

4 compartment stomach, alloenzymatic, regurgitate feed to chew a second time

hindgut fermentors

one compartment stomach, enlarged cecum, both mono gastric and ruminant digestion

cecal fermentors

capybara, rabbit, rat
primary site of fermentation is the cecum

colonic fermentors

horses, donkeys, humans
primary site of fermentation is the colon

salivary ducts

added during mastication, used to moisten the mouth

amylase

begins to digest starch

bicarbonate and mucin

neutralize stomach acid

why does salivary ducts have a greater importance in ruminants?

dds base to maintain proper pH (very acidic stomach), also allows for bolus to be created

What type of saliva is thin and watery?

Serus saliva

Which salivary glands produce serus saliva?

All three salivary glands

What type of saliva is very viscous (thick)?

Mucus saliva

Which salivary glands produce mucus saliva?

Submaxillary and sublingual glands

submaxillary salivary glands

base of tongue (mandibular)

sublingual salivary glands

underneath the tongue

parotids salivary glands

below the ear

esophagus

A muscular tube that connects the mouth to the stomach.

What is the primary site of chemical digestion?

Stomach

What type of tissues line the stomach to prevent stomach acid from damaging the stomach wall?

Mucosal tissues

How many separate areas is the stomach divided into based on the glands present?

Four

What are the names of the four areas of the stomach based on the glands present?

Esophageal, cardiac, pyloric, fundic

esophageal region

extension of the esophagus, most common area for ulcers

cardiac region

produces primarily mucus, protects stomach from gastric secretions, largest region in swine

which areas in the stomach area are primarily used for storage?

cardiac and esophageal region

What is the lining of the peptic/fundus region covered with?

Gastric pits

What do gastric pits open into?

Gastric glands

What do gastric glands produce?

A mixed secretion of acid, enzymes, and mucus

What are the two main types of cells in gastric glands?

Chief/peptic cells and parietal/oxynitic cells

chief/peptic cells

produces proteolytic enzymes

parietal/oxynitic cells

produce HCl

pyloric region

mucus producing cells

small intestine

highly coiled, most absorption occurs here, large surface area -> folds/villi, divided into 3 sections

duodenum

1st part of small intestine, produces various digestive secretions, pancreatic and bile secretions enter as well, lowest pH

jejunum

site of absorption, longest portion of SI, forms many coils

illeium

site of absorption, short and straight

What are villi in the small intestine?

Small fingerlike projections.

What do villi in the small intestine contain?

An arteriole, a venule, and a lacteal.

What is a lacteal?

A drainage tube to the lymphatic system.

Where do villi develop in the small intestine?

In the crypts of Lieberkühn.

SI brush border

microvilli and glycocalyx, help to catch particles for digestion

large intestine

made up of the cecum, colon, rectum, generally larger in herbaceous species, primary role is water and electrolyte absorption, some microbial fermentation occurs

liver

compact undivided gland, produces BILE, active site of synthesis and detoxification of metabolites

pancreas

light colored lobulated gland, produces pancreatic juice which contain enzymes to help with digestion -> amylolytic, lipolytic, proteolytic

where are digestive enzymes found?

saliva - small amount, glandular stomach - major source of proteolytic and HCl (produced in peptic gland region)

pancreas - important source of proteolytic, amylolytic, and lipolytic

small intestine - glandular wall of duodenum produces sugars, proteolytic, and lipolytic

Amyloytic enzymes prefer what substrates?

carbohydrates

proteolytic enzymes prefer what substrates?

protein

lipolytic enzymes prefer what substrates?

lipids

bilirubin

orange-yellow pigment in bile; formed by the breakdown of hemoglobin when red blood cells are destroyed

pepsin

proteolitic, secreted as proenzyme pepsinogen

rennin (chymosin)

secreted only in young animals, develops a milk clot, prevents overload of intestines

fat digestion

Result of emulsification of bile salts and the enzymatic action of pancreatic and intestinal lipases
Pancreatic lipase hydrolyzes fatty acids to produce 2 free fatty acids and 2 monoglycerides
Bile salts and hydrolyzed fats form the micelles which increase the surface area of the fat droplet

is the GI tract different in avians than other animals? true or false

true

what happens in the proventriculus?

gastric juices are produced

what does the gizzard (ventriculus) do?

used to mechanically reduce particle size

Do ruminants have upper incisors?

no

what are the 4 compartments of the ruminant stomach?

rumen, reticulum, omasum, abomasum

What does the reticulum move food into?

The reticulum moves food into the rumen and omasum.

What process does the reticulum facilitate?

The reticulum facilitates the regurgitation of ingesta.

Is there a true wall separating the rumen and reticulum?

no

rumen

large fermentation vat where bacteria and protozoa work, wall covered in papilla (increases surface area), serves as a point of microbial digestion

omasum

nickname is "many piles", role is not completely understood, aids in particle size reduction, helps control passage rate of ingesta, some absorption occurs

abomasum

similar to the glandular stomach in non-ruminants, provides chemical digestion of feed, different from other animals since feed has already gone through microbial digestion

pre-ruminants

young animals have an underdeveloped rumen, reticulum, and omasum
after consuming solid food stomach will reach adult proportions

reticular groove

Present in young ruminants so the milk they drink can bypass the rumen/reticulum into the abomasum

What is the process that occurs in the rumen before gastric digestion?

Microbial digestion

What type of environment do the reticulum and rumen provide for microbes?

Warm and moist

what 3 types of microorganisms are in the rumen?

bacteria, protozoa, and fungi

what two groups are carbohydrates divided into for ruminants?

fibrous (cellulose, hemicellulose) and readily available (sugars, starches)

what are readily available carbs digested by the microbes converted to?

VFA (acetate, propionate, butyrate)

what happens if an unadapted ruminant is fed readily available carbs?

increased risk of acidosis

what microorganisms consume dietary protein and resynthesize it?

proteolytic

what can ruminants use to meet protein needs?

non-protein nitrogen

anaerobic fermentation percentages in ruminants

CO2 - 65%
CH4 - 25%-27%
N - 7%

rumination

partially digested feeds regurgitated, allows for more complete chewing, increases saliva incorporation, spend about 8 hours/day doing this

what causes longer rumination?

course diets

eructation

The expulsion of gases orally; burping or belching.

what happens if the esophagus is blocked and a ruminant has a lot of gas?

bloat

what does the cranial parasympathetic neurons via the vagus nerve control?

esophagus, stomach, small intestine, and proximal portions of the large intestine

sacral segment of the spinal column controls?

distal portion of the colon, rectum, internal anal sphincter

nutrients pass across _______ in blood and lymph

the epithelial cells and into blood or lymph capillaries

nutrients are carried by ________ in blood and lymph

by portal vein to the liver or thoracic duct to the heart

where does the blood and lymph move waste to?

kidneys, where it can be filtered and excreted
waste can also move to intestinal epithelium to be excreted