Simple Stomach 2 Flashcards
What have enzymes been developed to do?
-incorporated into feeds to aid in digestion
What characteristics where developed into the enzymes?
-heat stability
-free flowing for handling ease when incorporated into diets
-stability for storage and feeding
What is the intention of adding feed enzymes to feedstuff?
-enhancing nutrient digestion
-maximizing digestible nutrients
-liberate nutrients
What is Xylans
-type of hemicellulose
-non-starch polysaccharide
-contains pentose xylose sugar
What does Xylan contribute to?
-cell wall of the plant
Where are Xylans found? and what is it?
-in feedstuffs
-as fiber has limited digestibility in non-ruminants
Why was Xylanase developed?
-to breakdown xylans in feed during digestion
What is beta-Glucans?
-another type of plant cell wall carbohydrate
-undigestible like xylan
Why was beta-GLucanase enzyme developed?
-to breakdown Beta-Glucan found in diets associated with feedstuffs
What are Xylans and beta-Glucans believed to do?
-bind nutrients
-restricting availability
-potentially influences digesta viscosity influencing nutrient absorption from the lumen in the gut
What does Proteases do?
-an enzyme that is incorporated into feeds that enhance protein hydrolysis
-intent is to support amino acid availability
What is the purpose of enzymes?
-improve nutrient utilization for health of animals
Who is enzymes most marketed towards?
-non-ruminants
What is the presumption for proteases?
-digestive enzyme capacity is insufficient for dietary protein levels
What is the presumption for xylanases and beta-Glucanases?
-these fibers could yield energy or are otherwise impacting nutrient availability
What does phytate do?
-hold on tight to phosphorus and minerals
What is phytate?
-also known as phytic acid
-inositol hexaphosphate
-storage form of phosphorus in cereal grains and oilseeds
-chelates: binds metal ions
What are Chelates and what do they do?
-Bind Zinc, Calcium, and Iron
-Chelation of these ions and others limit their bioavailability
-Absorption of minerals from phytate containing diets can be restricted
How much phosphorus in seeds is found in phytate form?
50-80%
Since phytate phosphorus is poorly digestible what happens to the diet?
-diets are supplemented with additional inorganic sources (like dicalcium phosphate) to meet requirements
When supplements are added to the diet like dicalcium what does it do?
-This effectively increases the total phosphorus in the diet
-with phytate phosphorus lost in manure
What is phosphorus essential for? a pollutant of?
-essential for plants and animals
-be a pollutant in water along with nitrogen (both found in manure and waste)
Phytate in animals, bacteria, and fungi
-Animals lack the phytase enzyme
-some bacteria and fungi produce it
How has the bioavailability of phosphorus from feedstuffs improved?
-by isolating phytase genes and producing them through biotechnology as feed additives
What does phytase partially liberate?
-improves bioavailability (both of phosphorus and minerals)
-reduces the total phosphorus in the diet from inorganic sources and therefore excreted phosphorus
What does phytate chelate minerals include?
trace minerals
Are trace minerals (their ions) important for other functions?
Yes
What are many brush border peptidases?
-Metalloenzymes
What is a metalloenzyme?
-enzymes that include a mineral ion in the catalytic portion of the enzyme responsible for enzyme activity
What can phytate do to metalloenzyme in the digesta?
-can be chelated: bound, rendered ineffective
What can feeding phytase do?
-improve protein digestion digestibility
What does TDN stand for?
Total Digestible Nutrients
What is TDN?
-energy system sometimes applied to ruminants and swine
-roughly similar to DE
-not expressed in energy units, expressed as a weight or percentage
-roughly converted to energy values
What is TDN getting replaced by?
The net energy system
Hoe many kcal De per pound of TDN?
2000 kcal
What do digestion trials identify when calculating TDN?
-digestible protein
-carbohydrates
-lipids
What are carbohydrates called in TDN?
-nitrogen free extract
-crude fiber
What do carbohydrates represent in TDN?
-the non fiber carbohydrate and fiber, but these identities are not pure or clear
What are lipids estimated from in TDN?
ether extract
What does ether extract capture?
-fats in feeds
-but also non-nutritive lipids like pigments
What is ether extract multiplied by? and why?
-2.25
-to reflect added energy density of fats compared to carbohydrates
What is feed TDN calculated from?
-digestibility experiments that are many decades old
What are problems with TDN?
-intake levels were lowers in the experiments and digestibility is known to be influences by intake level
-feeds are variable in quality depending on conditions and ascribing TDN values for a specific feedstuff years ago has limitations in application today
-reporting of crude fiber in feed analyses has been replaced with estimates of fiber based on the detergent fiber system
