Exam 1 Flashcards
What are the 4 major digestive processes?
Mechanical, chemical, enzymatic, and fermentative
How many grams in a pound?
454
How many pounds in a kg?
2.2
How much is a bushel?
56lb
How do we classify animals digestively?
Based on where fermentation occurs
Ruminant
Complex
Monogastric
Simple
Functions in GIT: Mouth
Primarily mechanical, some enzymatic, prehension of food, start digestion, and taste
Functions in GIT: Saliva
Lubrication, buffer, nutrients from rumen microbes, prevention of rumen frothing, protection of mouth
What taste receptors do cats not have?
T1R2 - Sweet
Composition of Saliva
water, mucin, bicarbonate salts/ electrolytes, enzymes in some species
Functions in GIT: Stomach
Mechanical, chemical, and enzymatic digestion, feed storage, reduce particle size of feed, mucous secretion, low pH kills bacteria and activates enzymes
What is the hunger hormone?
ghrelin
Functions in GIT: Small Intestine
Mechanical and enzymatic digestion and absorption of nutrients
Where does bile enter GIT
duodenum
Where does bile go after digestion?
98% recycled back to liver
Pancreatic secretions?
Digestive enzymes and bicarbonate
Brush boarder enzymes?
Sucrase, maltase, lactase, aminopeptidases, dipeptidases
Functions in GIT: Large Intestine
Mechanical and fermentative digestion, water and mineral absorption, fiber digestion in nonruminants, synthesis of vitamins B&K, production of VFAs for enterocytes
Avian Differences?
No teeth or amylase, crop for feed storage, proventriculus acts as stomach, ventriculus grinds feed, ceca, cloaca
Ruminant differences?
No enzymatic digestion in mouth, saliva recycling of N Na P and H2O
Ruminant SI
no sucrase
Site of fermentation in Ruminants?
rumen, reticulum, and omasum
Primary loss of water
In urine and feces
6 Major classes of nutrients?
Water, protein, fats, carbohydrates, vitamins, minerals
“true” stomach of rumen?
abomasum
Standard Proximate Analysis System?
Weende system
Weende system
water, protein, fat, total minerals, and some carbohydrates
Detergent Analysis System?
Van Soest system
Ash
Minerals -inorganic
Nitrogen-free extract
estimate of digestible carbohydrates
NOT determined via laboratory analysis - it is calculated
How is dry matter measured?
heating the sample in a drying oven until there is no change in weight - typically takes 1-5 days
Is moisture on feed labels?
Yes
Why does nutrient ratio increase when going from as-fed to dry matter?
Water dilutes the nutrients we care about
Organic matter % =
100% - Ash %
Where is material oxidized to measure ash?
Muffle furnace
What might high ash indicate?
soil contamination
Problems with measuring ash?
No indication of individual minerals & some minerals are lost
Methods to measure nitrogen precent?
Kjeldahl and LECO
Crude Protein % =
% Nitrogen * 6.25
Why is 6.25 the N conversion factor?
(on average) proteins contain 16% nitrogen
Non-Protein Nitrogen
Free amino acids can be used to meet AA requirements of nonruminants and protein requirements of ruminants
Problems with CP
No indication of protein quality, only measures N not the source, and no indication of digestibility or rumen degradability
What animals should eat RUP/bypass protein?
fast-growing feedlot animals & high high-producing dairy animals
Problems with ether extract?
EE consists of true lipids and other ether-soluble compounds like fat-soluble vitamins, waxes, chlorophyll etc.
Crude Fiber:
not accurate but theoretically represents structural carbohydrates
Nitrogen-Free Extract represents
Starch, sugar, and digestible carbohydrates - typically overestimated
Most digestible structural carbohydrate? Least?
Most: Cellulose
Least: Lignin
NDF
cell wall components
cellulose, hemicellulose, lignin
highly related to feed intake/gut fill
ADF
cellulose and lignin
highly related to feed digestibility
TDF
Most accurate way to get true fiber
Used in human food industry but not widely used in animal feed industries
Very labor intensive and expensive
Heat damage
referred to as Maillard or Browning reaction - reduces digestibility
Heat damage is determined by?
Acid Detergent Insoluble Nitrogen
Determine nitrogen attached to the ADF residue
