nutrition/dietary history Flashcards
what is a forage?
leaves/stems of plants eaten by grazers
what percentage of feed is provided by forage?
50-100%
what does a pasture do in terms of nutrition?
provides sufficient quantity and quality of forage to sustain a particular group of livestock nd generate a profit for the farmer
what is the main carbohydrate found in forages?
fibre
what is lignin?
- major component of the cell wall of older (mature/late cut) forages
- As the plant matures, lignin content increases because the grass and crops accumulate lignin in their stems as they mature so they can stand upright and support seed heads
why is young grass more digestible?
- lower lignin content
what does lignin do to limit microbrial access to polysaccharides so they cant ferment the fibre?
lignin cross-links to the polysaccharides of the plant cell wall, the cross-links form a barrier that limits microbial access
what affects the digestibility/feed value of forage? (3)
- feed availability / seasonality
- species
- growth stage
how does seasonal variation affect feed value of forage?
- little growth in winter
- most abundant in spring
- summer dependent upon rainfall
- declining through autumn
how do stocking levels affect forage availability
- balance between animals grazing and grass growth
- required grass management
- rotation
- fertilisers
- harvesting excess
how does species affect digestibility/feed value of forage?
- what is growing?
- persistency
- productivity
- nutritive value
how does the growth stage affect the digestibility/ feed value of forage?
- young grass is highly digestible
- older grass is less digestible
- digestibility dependent on lignin content, ratio of cell wall to cell contents, and type of fibre
what is the D value?
digestibility
what are the 2 methods of conservation for forage?
does it result in high or low moisture?
- natural fermentation/pickle: high moisture
- drying: low moisture
describe silage.
- young grass
- highly digestible
- less herbage mass
- cut may/june
- preflower
what are the 2 ways silage can be prepared/fermented?
clamp or baleage
how does clamping work in the process of fermenting young grass to silage?
- chopped as cut
- limited wilting, remove 25-40% water
- put into pits
- oxygen excluded by packing or covering
- anaerobic fermentation to reduce acidity - ph
how does baleage work in the process of fermenting young grass to silage?
- not chopped
- slightly more wilting
- wrapped in bales
what is wilting?
leaving mown grass or forage in the open to dry partially before being collected for silage
what is the pickling process?
- anaerobic (excludes oxygen)
- sugar in the grass converted to lactic acid, lactic acid bacteria multiply and grow
- as the environment acidified, the plant enzymes and stop and degrading bacteria stops
- when ph is 3-4 it inhibits lactic acid bacteria
- crucial ph is not too high or low
- preserves forage/crop
in the pickling process, what happens if the ph is too high or low?
too high = secondary fermnetation
too low = unpalatable
fermented older grass results in haylage for horses, what is the process?
- more mature grass cut in early July, jut after flowering but before seeding
- not chopped
- wilted to remove 50-75% water
- it is baled and wrapped in smaller packages of around 20kg
- less acid, drier, less nutritious than silage
what is process of turning grass to hay?
- mature grass
- cut mid July after flowering and just before or after seeding
- not chopped
- left in field to dry and wilt, removing 85% of water
- not wrapped
- stored inside/usually a barn
what is straw?
by-product of cereal harvest not grass
