1.7 Feedstuffs - Cereals Flashcards
What are cereal grains?
Edible grains of cultivated grasses
- ex. wheat, rice, corn barley, oats, rye sorghum, triticale, buckwheat
What is the most important cereal grain for pigs? Poultry?
Pigs: barley (prairies), corn (globally)
Chickens: wheat (prairies), corn (globally)
What is the basic structure of all cereal grains?
- Hull
- Fibre (NSP) - Aleurone
- Fibre (NSP) + protein - Endosperm
- Starch
- highly developed - Germ
- Oil (fat) + protein
Pertaining to the type of cereal grain, as there are more soluble NSPs present, what is there less of?
DE
- ex. corn has the highest DE, oats have the lowest DE
What are the 2 forms of starch?
- Amylose
- long chains of a1-4 linked glucose units
- tight helical structure
- more resistant starch - Amylopectin
- some a1-6bonds with branches
- higher digestibility than amylose
Why is starch gelatinized?
- Causes granules to swell and lose crystallinity
- Higher digestibility
- The protein matrix is a potential barrier so needs to be broken
Where are starch granules found?
Within the protein matrix
- which is a potential barrier
- also GE digestibility ~ CP digestibility
What does the rate of degradation of starch granules depend on?
Proportion of amylose vs amylopectin
- rapid digestible starch
- moderate rapid digestible starch
- moderate slow digestible starch
- slow digestible starch
What does non digested starch act like?
Fiber = substrate for microbial fermentation
What 2 things is corn high in?
- UFA
- carotenoid pigments
What is the effect of corn FAs on pork quality?
- high levels of UFA
- negative effect on quality bc carcass FA composition reflects dietary comp
- UFA very liquid at room temp = greasy pork
What is the effect of corn carotenoids on chicken and egg yolk appearance?
Colour!
- yellow chicken skin
Why are oats high in fat, yet low in DE?
Bc oats are high in fiber
Protein quality of cereal grains
wheat > barley and oats > corn
*feed cereal grains bc of the starch (energy) they provide but still contain protein; bc most of the diet is composed of cereal grain, they contribute a substantial proportion of CP
Fiber/soluble NSP in cereal grain
Oats > Barley > Wheat & Cron
- Barley contains B-glucans = supplement B-glucanase
- Wheat contains arabinoxylans = supplement xylanase
- w/o supplementing enzymes, the soluble NSP is fermented by the microbes instead
Can animals break down B bonds of CHO?
NO! But microbes can
- can supplement enzymes as well
What is the potential problem with soluble fibre/NSP? How is this controlled?
Soluble fibres in gut:
- decreases diffusion of digestive enzymes, nutrients
- increases bacterial load
- sticky feces
Control by using supplemental enzymes
- Arabinoxylanase, B-glucanase
- match enzyme activity to the major NSP(s) present
What 4 aspects of cereal grains have been genetically modified?
- Starch form and availability
- amylose vs. amylopectin
- fermentable vs. digestible starch - AA content
- high-lysine corn and barley - Oil content
- high-oil corn - Phosphorus digestibility
- low-phytate corn and barley = decrease in ANF
What is the nutritional value of oat hull removal?
Dehulling removes indigestible NSP
- left with oat groats and oat hulls
- groats: highly digestible
- hulls: virtually non-digestible
Barley fractionation
- removal of barley hull
- hull-less barley can be genetically selected for
What is ‘fractionation’?
Dehulling! Which contains the NSPs
Energy content of cereal grains
corn > wheat > barley
*barley and wheat are the main grains in AB
