Transcript Livestock Nutrition

Livestock Nutrition
Chapter 8
Feed Quality and Feed Analysis
Objectives
• Describe quality Characteristics of grains
and other feeds.
• Describe methods of harvesting quality hay
and silage.
• Describe the analysis of feedstuffs.
• Describe methods of measuring the value of
feeds.
• Describe regulations relating to the
manufacture and sale of feed stuffs.
Feed Quality
• Quality of feed affects its value for animal
nutrition.
• Quality factors include palatability and
nutrient content.
• Improper harvesting or handling will reduce
quality.
• Palatability refers to how well the animal
will accept feed.
Feed Quality
• If an animal does not find a feed palatable it
will not eat enough, make good gains, grow
properly or produce meat, milk or eggs.
• Feeds on produced on well fertilized soils
will produce feed, especially roughages,
that is of a higher quality.
• Vitamins, amino acid content and minerals
will also be affected by soil type.
Harvesting Hay for Quality
• Quality of hay is affected by harvesting and
handling methods.
• Stemmy hay with fewer leaves is of lower
quality, because the leaves contain the most
nutrients and are the easiest digest.
• Shattering is the loss of leaves due to
harvesting and handling.
Harvesting Hay for Quality
• Legume hays will shatter easier than grass
hays.
• Moisture content of hay must be reduced so
it can be stored without spoiling or serious
loss of nutrients.
• Field forages must not contain more than
18-22% moisture for baling.
• Factors affecting moisture content include,
humidity and movement of air, fineness of
forage and how compact the bale is.
Harvesting Quality Hay
• Shattering, leaching and bleaching are 3
things that cause loss of quality during
harvesting.
• When forages get too dry, leaves tend to
shatter.
• Forage that is rained on while curing will
suffer loss of quality by leaching, (loss of
water soluble nutrients.
• Bleaching occurs when the forage has cured
to long in extremely hot temperatures.
Harvesting Quality Hay
• Forages should be cut as soon as possible
after reaching the early bloom stage of
maturity.
• If hay is not conditioned it will require two
days of drying before it is ready to bale.
• Conditioning breaks the stems, reducing the
amount of time that it takes dry the hay.
Harvesting Quality Hay
• Hay should be baled as soon as possible
after it reaches a safe moisture level for
storage.
• Delays in baling at this point will increase
the chances of losing nutrients to bleaching
and leaching.
• If small square bales are not stored under
cover they will lose quality due to moisture,
causing musty and moldy bales.
• Rain and snow can easily soak a small bale
stack through and through
Producing Quality Silage
• When high moisture crops are stored under
anaerobic, without air, conditions, a
fermentation process occurs that produces
silage.
• Crops may be stored is vertical or horizontal
silos.
• Vertical silos require less land, less spoilage
and require less labor for unloading.
Vertical Silos
• Can be either conventional or gas tight.
• Conventional are constructed of concrete
staves, metal, or cast in place concrete.
• At time of ensiling crop should contain 2535% moisture.
• If crop is to high or low in moisture,
spoilage will be high.
• Gas tight silos are constructed to eliminate
air, ensure preservation and storage of
forages with a range of approximately 2575% moisture.
Horizontal Silos
• Trench, bunker and stack are the three types
of horizontal silos.
• A trench silo is usually dug into the side of
a hill, a concrete bottom is recommended
due to mud and water.
• Filling is accomplished with dump trucks or
wagons.
• After filling the pit is covered with a
polyethylene sheet and weighted with dirt,
concrete blocks or boards.
Horizontal Silos
• Bunker silos are posts and boards with a
side lining of building paper or plastic.
• Bunker silos are above ground, while pit or
trench silos are below ground.
• Bunkers silos are usually made with a
concrete floor as well.
Horizontal Silos
• Stack silos require a small investment and
may be used for emergency storage of
surplus silage.
• Silage is spread in shallow layers using
tractors, the sides should slope 60 degrees.
• During filling the silage is packed with a
tractor.
• When filling is completed, the top of the
stack is rounded off, black plastic 4-6 mil
thick, is used to cover the stack.
• The slack should be always taken out of the
plastic with the weights on the side.
Physiological Changes in Silo
• The most commonly used silages are corn
and sorghum.
• Crop should be at 62-68% moisture before
ensiling.
• If crop is too wet it will not produce lactic
acid but butyric acid, causing a sour feed
with high nutrient loss.
• If it is too dry it will mold easily.
Physiological changes
• It takes about 21 days for the fermentation process
to complete.
• Living cells continue to burn plant sugars, use
oxygen, and give off carbon dioxide, water and
heat.
• Acetic acid is produced early in the process and
plant pH changes from 6.0 to 4.2.
• After 3 days, the formation of acetic acid slows
down and lactic acid is formed.
Physiological changes
• Formation of lactic acid continues for about
another 2 weeks and the temp decreases.
• Bacterial action stops when pH reaches 4.
• If conditions are have been right, the silage is now
fairly stable, and will remain so for a long period
of time.
• The ideal temp is 80-100 degrees, if temp is lower
butyric acid is formed, causing foul odor and
breaking down the protein.
• Higher temps cause caramelized silage is formed,
it is sweet tobacco smelling, it is higher is
palatability but low in nutrient value
Harvesting Crops for Silage
• Corn should be harvested at the dough to
hard dent stage, 32-38% moisture.
• Grasses and legumes should be wilted to
below 65% moisture.
• Grasses should be ensiled in the early
heading stage and legumes at about one
tenth bloom.
• Small grains are harvested for silage in the
boot to early milk stage for best results.
Silages
• Grass and Legumes should be chopped at
one quarter inch.
• Dry matter losses are kept to a minimum
when grasses and legumes are stored in the
silo at 50-65%.
Adding Dry Matter and
Preservatives
• Many things are added to silages to reduce
moisture, aid in curing and increase
palatability.
• Dry grain, is added to reduce moisture,
however it may not be economically
feasible.
• Chemicals increase palatability but also
may not be financially feasible.
Important other Factors
• Rapid filling, even distribution, packing and
prompt covering of silages.
• Legumes that are higher in protein will spoil
quicker.
• Grass silage does not keep well in trench or
bunker silos.
• Corn silage should be chopped to 1/4 -3/8
of an inch.
• Corn should be filled quickly and evenly.
Feed Samples for Analysis
• Sample must be carefully secured to
accurately represent a much larger quantity
of feed.
• Less than one quart of feed is usually
submitted.
• There are many was to sample, hand,
harvest, core and bulk feed. Moisture
content should always be consistent as
possible.
Proximate Analysis of Feedstuffs
• Feed using chemical and mechanical means
is separated into 6 components.
• Water content, crude protein with Kjeldahl
process, crude fat, crude fiber, minerals,
and Nitrogen free extract.
Limitation of Proximate
• No indication of palatability, digestibility,
toxicity or nutritional value.
• Feeding trials with live animals are
necessary to determine actual worth of a
feed for practical feeding purposes.
• Organic components of the feed, crude
proteins, amino acids, ether extract and cell
wall may vary in individual fees as much as
15% more or less than the table values.
Feed Composition Basis
• All feeds contain moisture, depending upon
the form fed, time harvested and storage
time.
• As fed means the data is calculated on the
basis of the average amount of moisture
found in the feed as it is used on the ranch.
• 100% dry matter basis means that the data
presented is calculated on the basis of all
the moisture removed from the feed.
Van Soest Method
• Neutral detergent soluble is lipids, sugars,
starches and proteins.
• Neutral detergent fiber is the more insoluble
material found in the cell wall.
• Consists of cellulose, lignin, silica,
hemicellulose and some protein.
• Acid detergent fiber consists of cellulose,
lignin and some silica.