coursera week 3 DAIRY PRODUCTION AND MANAGEMENT

lossary
β-glucans: Soluble fiber found in barley grain
By-product: Animal feed, usually a waste product from the food industries
Colony-forming units: A measure of the number of viable bacteria
Ergot: Fungus growing on rye
Ergotamine: Toxin produced by ergot
Extruder: A screw-press used to extract oil from oilseeds and to produce oilseed meal for
animal feed
Flaking of grain: Grain processing involving heat and steam that leads to starch gelatinization
Gelatinization: A process of breaking down the intermolecular bonds of starch molecules in the
presence of water and heat
Ionophoric antibiotic: An antibiotic selectively inhibiting certain microbial species in the
rumen
Mailard reaction: Chemical reaction between amino acids and reducing sugars at high
temperature that gives feeds brown color and flavor (and also decreases protein availability)
Non-protein nitrogen: Nitrogen from mineral source, such as urea
pH: A measure of acidity or basicity of solutions
Rumen-protected: Feed additive that is coated or in some other way protected from attacks by
the rumen microbes
Silage inoculant: A microbial additive used in ensiling to stimulate fermentation (usually lactic
acid) and improve silage quality
Yeast: In animal nutrition, live yeast or yeast culture used as animal feed
Conversion Matrix
1 inch = 2.5 cm
1 kg = 2.2 lbs.


Temperature conversion = Temperature (T) in degrees Fahrenheit (°F) is equal to the
temperature (T) in degrees Celsius (°C) × 9/5 + 32
Hello, my name is Alex Hristov and
I'm a Professor of Dairy Nutrition at Penn State University.

The next few lectures we'll discuss specific feeds discussed in dairy rations.
First, I will remind you that we classify dairy feeds into two major categories,
forages and concentrate feeds.
Forages can be very diverse and with large variation in chemical composition and
nutritive value.
For example, as plants mature, forages deposit more in digestible material,
such as legume and their nutritive value decreases.
Concentrate feeds include grains, oilseeds, by-products and
minerals and vitamin supplements.
In addition, in dairy nutrition, we use a long list of feed additives.
Examples of feed additives include synthetic amino acids, non-protein
nitrogen, additives such as urea, yeast products, rumen buffers and others.
So first, we'll start with foragers, please also remember to listen to Dr.
Roth's lectures on dairy forages from an agronomic standpoint.
Forages are by far, the most important feeds in a dairy ration.
Their quality determines the quality and nutritive value of the entire diet.
They are also the most variable in composition components of the diet.
Typical forages in dairy ration in countries with temperate climate and
good silage, alfalfa, rice in cool season, warm season grass is for
grazing or silage making [INAUDIBLE] grass and others.
In North America, the main formation to the Russian is corn silage.
Corn silage will typically have a content of around 33 to 35%.
Neutral Detergent Fiber around 45%, crude protein,
8 to 9% and starch can be anywhere from 24 to 38, 40%.
Corn silage is usually processed with corn process of during harvest,
the advantages being better in silo fermentation,
low silage losses and increased digestibility.
Corn silage is fed to cows as a source of digestible energy from both fiber and
starch.
Its protein content, however is low and the true protein is deficient in lysine,

which is a key amino acid in farm animal nutrition.
Optimal stage for harvest for corn silage is three-quarters to
one-third milk line in the kernel and about 33 to 35% dry matter.
Digestibility of both the stover, which is the fibrous part of the plant and
grain may be higher in early maturity.
For example, early dent and 30% dry matter, but total harvest of digestible
organic matter per acre will be lower due to the lower starch content.
Silage harvested to high maturity black layer of the kernels and above 37% dry
matter will have decreased starch in total organic matter digestibility.
Corn silage can be fed as the sole forage to lactating dairy cows.
High quality corn silage is a recipe for successful dairy farming.


Main point to remember is that stage of harvest is critically important for
silage quality.
Another critical factor for corn silage quality is the process of insiling,
which we'll discuss in a following lecture.
The second most important forage in North American dairy diets is alfalfa hay or
haylage, which is a forage kind of restricted 40 up to 60% dry matter.
It should be pointed out here that there is little to no difference in milk
production between well-preserved silage or haylage and
hay made from the same forage.
However, the feeding value of both silage and hay can dramatically decrease
if in silage practices are compromised or field losses are high due to rainfall.
Recommended silage and
hay making practices will be covered in a separate lecture.
Alfalfa is referred to as the queen of forages and
is an extremely valuable crop for dairy cows.
Typically, alfalfa haylage will be around 40% dry matter will
have around 18 to 20, 21% crude protein.

43 to 45% Neutral Detergent Fiber and will have high levels of calcium and
other minerals, considerably more than co-signage.
We feed alfalfa as hay or haylage today cows,
because of it´s high digestible protein content.
Digestible fiber, calcium and
also digestible non fiber carbohydrates such as pectins.
Compared with corn silage, fiber in alfalfa is more rapidly digestible, but
total digestibility will be lower, because of higher content.
The high protein count of alfalfa,
particularly haylage is a blessing can curse at the same time.
This is because alfalfa protein is highly digestible and converted to a great extent
into non-protein nitrogen in the silo, all the rumen and large portion of it
is eventually lost with urine and can not be efficiently utilized by the dairy cow.
Optimum maturity for harvesting alfalfa is mid to late-bud and
maximum take 10% bloom.
Yield per acre will increase with more mature plants, but as with corn silage,
the digestibility of the harvested forage will decrease.
Other legumes, such as various types of clovers, sainfoin, soybean and
pea forages can also be fed to dairy cows as silage or grass legume pastures.
Grasses as pasture of silages alone or in combination with legumes
are an excellent source of digestible fiber and energy for dairy cows.
In climates without foliage crops such as corn, for example, may not grow well.
Grasses are the primary foliage for dairy cows.
Some reasons to grow grasses include greater seeding year yields,
wider harvest window and second and later cuttings, faster dying time and
as a source of digestible fiber in diets that are high in corn silage and starch.
Production systems in dairy power houses,
such as New Zealand and Ireland are almost entirely based on grass silage.
Typical grass silage will have around 40% dry matter,

55 to 60% Neutral Detergent Fiber and 16 to 18% crude protein.
Fiber in grass silage is digested at a lower rate, but
to a greater extent than fiber from legumes.
This means that grass silage could serve as a source of digestible fiber
in the ration.
Species can vary, but in the US most common grasses include perennial and
Italian ryegrasses, tall fescue, orchardgrass, thimothy,
bromegrass and others.
Recommended stage of harvest is late-buds to early head.
In the pasture-based systems of New Zealand, the main forage for
dairy cows is a perennial rye grass/white clover mix.
Small grain silages such as barley, wheat, triticale and oats are grown in Northern
and temperate climates as forage crops, often as cover crops on dairy farms.
Typically, this forage is used to make silage that contains around 35% dry
matter, 58 to 60% Neutral Detergent Fiber and 12 to 14% crude protein.
These plants are very sensitive to the stage of harvest and their quality and
digestibility.
Rapidly declines as the plant matures.
These forages are harvested at flat leaf stage, for example,
wheat or early to mid-dough and even early to mid stage barley, and oats.
Yields will increase as the plant mature, but
digestibility will dramatically decrease.
A number of other forage crops can also find place on a dairy farm for
various reasons, including favorable ergonomic characteristics.
For example, drought resistance, early to late harvest,
specific desirable nutrient or nutrients.
For example, high sugar grasses species or environmental advantages,
such as high nitrogen and uptake from heavily fertilized soils.
In our next lectures, we'll discuss energy and protein feeds, by-product feeds and

feed supplements.
Hello and welcome back.
We'll continue our lectures on feeds for dairy cows.
Next we'll discuss concentrate feeds and we'll start with cereal grains.
In the U.S. and other countries, corn is the main energy grain fed to dairy cows.
Of all crops, corn yields the most digestive organic matter per acre.
It is highly energetic feed because of its high starch content.
It's relatively low protein, around 9%, and about 4 to 5% oil.
The oil is high in unsaturated fatty acids.
Corn has to be cracked or ground before being fed and
its nutritive value would depend on the method and
extent of processing, which we'll cover in a separate lecture.
A similar extent of processing,
degradability of corn starch is lower than most other cereal grains.
Which is advantageous in their nutrition, because higher rates of starch
degradability can cause room in lactosis and decreased milk fat test.


Corn grain can be safely fed to dairy cows and
can make up the entire concentrate portion of the ration.
As all cereal grains, corn is low in calcium and high in phosphorus.
Yellow corn is high in beta carotenes, which is a vitamin A precursor.
And corn grain can be harvested moist at around 22 to 28% moisture and in salt.
This is called high-moisture corn and has higher rate and
extent of starch digestibility and energetic value compared with dry corn.
Another important grain for dairy cows is barley.
Barley is high in protein, around 12 to 13% and
neutral detergent fiber around 20% because of its fibrous hull, than corn.
And has compounds that are indigestible for pigs and poultry such as beta-glucans.
These compounds however are not a problem for ruminants.

Because of its higher fiber content, barley has low energy value than corn.
Barley starch is considerably more degradable in the rumen and
may cause digestive disturbances if fed at higher levels, and
the animal has not gradually adapted to the diet.
In many countries wheat grain is also regularly fed to dairy cows.
Wheat is palatable and has higher protein content than corn and
even barley, around 14%.
But it's starch is highly degradable in the rumen and
is depletion usually avoided in diets for dairy cows.
When fed, it should make up no more than half of the grain in the ration.
Many wheat by products are also used as dairy feeds.
Some other cereal grains, such as oats, rye,
or triticale may also be fed to dairy cows as an energy source.
Rye and triticale, which is a hybrid of wheat and rye,
are high in protein around 15% but may be susceptible to a fungus,
ergot, which produces a toxin called ergotamine.
Oats are palatable feeds with high fiber content,
around 30% nitrogen fiber, and with a low energy value than other grains.
Oats can be safely fed to dairy cows when they're available.
Last but not least, sorghum grains can be fed today to cows in the US, and
they are also important dairy feed in other countries.
There are many sorghum varieties, and
an average chemical composition may be misleading.
Sorghum has more protein, around 11 to 12%, but less oil than corn.
Darker varieties have higher tannin content which may decrease protein
digestibility.
Sorghum has around 90-95% of the energy value or corn grain.
It has to be processed because of the small kernels or
otherwise a portion of it will partially digest into feces.
Another category of feeds for the cows is protein concentrate feeds.

Protein feeds are valued because of ruminal undegradability,
amino acid composition.
And last but not least price.
Cost of protein feeds should be converted to my unit of protein base and


then the feeding value of the protein should be evaluated based on concentration
of key digestive limiting amino acids such methionine, lysine, and histidine.
The most important feed in this category is, soybean meal, which is also the most
important protein feed for other farm animals including bison.
Soybean meal is essentially a byproduct of soybean processing industry.
It's valuing animal nutrition however such that it counts for
50 to 75% of the value of the soybean processing industry.
Soybean meal is high protein, typically around 50% crude protein feeds.
That can be savory fat to dairy cows as the major protein supplements in the diet.
Soybean meal protein is of high quality bean almost entirely too protein.
There are two types of soybean meals, solvent-extracted and
expellar, named after the processes used to extract the oil from the beans.
Solvent-extracted meal has little oil left, around 1 to 2%,
while expellar soybean meal can have up to 8 or 10% residual oil.
Extracting oil by expellar creates high temperature which
partially protects the soy bean protein from microbial degradation in the lumen,
thus increasing the feeding value of the soybean meal for ruminum animals.
In addition to having more valuable protein axpeler,
or extruded soybean meal, has energy value,
down solvent extracted soybean meal because of its high oil content.
During the extrusion process the heat creates browning combine with reactions
which give specific reddish cower to the excluded meal.
Overheating is not desirable because protein digestibility may decrease.
There are number or commercial products essentially heat dated soybean meals

that are designed to deliver amino acids to the cow post rumen.
Similar to cereal grains, oil seeds have lower calcium but higher phosphorus
concentration compared to a typical dairy forages except corn silage.
Whole soybeans, raw or heat treated are also commonly fed to dairy cows in the US.
Oil in raw soybeans may deteriorate over time
because the seed contains lipase enzymes that may hydrolyse the oil and
release free fatty acids that will cause the beans to become rancid.
All soy beans can be roasted to 310,
320 degrees farenheit, which is 150, 160 degrees celsius, and
then for the process half to a quarter, but not ground, before being fed.
The advantage of roasting soy beans is that the high temperature increases
The lumen bypass protein which is more valuable to the cow
than the rumen degraded protein which soybeans have plenty of.
All soybeans also have high energy value because of the oil in them which is 18 to
19% Thus, whole roasted soybeans are an excellent
source of digestible energy and rumen bypass protein for dairy cows.
Because of their high unsaturated oil content, whole soybeans should not be fed
to more than 20% of the concentrate portion of the ration.
We'll continue discussing protein feeds in our next lecture
>> Hello and welcome back.
In this lecture we'll continue our conversation on protein and
byproduct feeds and feed supplements for dairy cows.


Canola rapeseed meal is another popular protein feed for dairy cows.
Canola is rapeseed that has been bred to be erucic acid and glucosinolates free.
Canola meal is higher in fiber, around 29, 30% Neutral Detergent Fiber.
Low in protein which is around 38%.
And is usually slightly higher in oil than soy and extracted soybean meal.
An advantage of canola or

rapeseed meal is it's higher methionine content compared with soybean meal.
As already discussed, methionine is a key limiting amino acid in dairy diets.
Most recent data has shown that dairy cows produce more milk when with fed canola
versus soybean meal.
Sunflower meal is a byproduct from the sunflower oil industry and
can also be fed to dairy cows.
It has higher fiber, 40% Neutral Detergent Fiber depending on the method
of processing, and lower protein around 28% content.
And thus, its feeding value is lower than soybean and canola meals.
Its protein has higher concentration of methionine but
it is also more degradable in the ruminant.
Where available whole cottonseeds or
cottonseed meal can be a valuable protein supplement for dairy cows.
Whole cottonseed is also high in digestible fiber,
around 50% Neutral Detergent Fiber, and energy due to its high oil content,
around 90%, and can be fed up to 10% of the ration dry material.
The meal, following the oil extraction has around 45% good protein,
but unless it's a gossypol-free variety, may have high levels of gossypol,
which is toxic to farm animals.
Meals from other oil seeds or oil plants,
for example flax, safflower, peanuts, coconut, which is a copper meal, or
legume seeds such as peas and beans, can be in the ration of dairy cows.
In all cases it is important that we know the chemical and
mineral acid composition, ruminal degradability and presence of any toxic or
anti-nutritional factors in these feeds.
Where our regulations do not specifically prohibit it,
animal proteins can be included as a source of amino acids in dairy diets.
Typical animal protein feeds are blood, meat, bone, and meat meals,
poultry byproduct meals, feather meal, pork meal, and others.
Blood meal can be extremely variable in its quality and attention should be paid

to the source, processing, and nutritional specifications provided by the supplier.
If overheated during processing, intestinal digestibility of the amino
acids in blood meal will be drastically decreased.
Fish and shrimp meals can also be fed to dairy cows depending on quality,
availability and price.
These meals are good sources of amino acids but are usually expensive,
have a short shelf life, are not very palatable, and
in some cases may alter the flavor of milk.
Other byproduct feeds include distillers grains from the ethanol industry and
brewer's grains from the brewing industry.


Both sources of rumen bypass protein.
Various corn and wheat milling byproducts, bakery byproducts, soy,
cotton seed, and almond hulls which are all sources of digestible fiber.
Beet and citrus pulp, again, sources of digestible fiber.
Sugar beet or cane molasses, palm kernel meal, potato and
rice b-products, animal fat and others.
Cows particularly like sweets, and inclusion of molasses in the diet may
have a beneficial effect on feed intake and milk production.
Our lecture will not be complete if we don't discuss briefly the most common feed
additives used in dairy diets.
There is a long list of feed additives on the dairy market.
They are all designed to more or less successfully increase milk production,
improve milk composition, for example, increase milk fat and
protein concentration, and/or enhance animal health.
An incomplete list of feed additives will include yeast cultures and
probiotics of various kinds.
They are designed to enhance rumen fermentation or targeting gut health.
Anionic salts for transition cow diets.

Various vitamin and vitamin-precursor supplements such as biotin,
beta-carotenes, niacin, non-protein nitrogen sources including
slow-release urea nitrogen products, enzymes.
Usually designed to increase digestibility of feed fiber.
Antibiotics including ionophores such as monensin and lasalocid,
which are both designed to modify rument fermentation.
Propylene glycol, calcium-propionate, rumen-protected choline,
rumen protected amino acids.
We should remember that unprotected amino acids will
be destroyed by the bacteria in the rumen.
Buffers to stabilize rumen pH such as sodium bicarbonate, magnesium oxide,
and others.
Essential oils and plant derived bioactive compounds such as saponins and tannins.
Perhaps the most commonly used feed additive in the dairy industry
are yeast cultures.
Yeast are grown in commercial fermenters, processed, and
then included in the diet of dairy cows.
Beneficial effects include more stable rumen fermentation, increased feed intake,
and increased milk production.
Rumen-protected amino acids such as lysine and methionine
are used to provide digestible limiting amino acids to high-producing dairy cows,
particularly when the total protein content of the diet is relatively low,
which is about 16 or less percent.
Ionophoric antibiotics have a long history of used in the beef industry and
have relatively recently been approved for
use in the dairy industry in the United States.
Their main mode of action is to modify rumen fermentation,
making it more efficient, which usually results in increased feed efficiency of

the animal, which means producing more milk with similar or lower feed intake.
With this variety of feed additives, dairy farmers and
professional nutritionists are often confused how to interpret the benefits,
particularly cost benefits, of using additives in their ration.
One thing we have to make clear, no feed additive cannot substitute for
good understanding of animal needs, feed, particularly forage quality,
and basic diet formulation.
We have have to mention non-protein nitrogen products,
which are use in ruminal diets as a source of nitrogen for
the rumen bacteria to produce microbial protein.
This protein is in turn used by the cow as a source of amino acids.
The most common non-protein nitrogen source in cattle diets is urea.
Urea is broken down to ammonia in the rumen and the microbe use it,
provided they have sufficient energy for synthesis of their microbial protein.
Ammonia, however,
is toxic, and too much urea ingested too quickly can kill the animal.
Inclusion levels of urea in dairy diets usually does not exceed 1 to 1.2% of
dietary dry matter.
We have to remember, however,
that non-protein nitrogen cannot be a substitute for
high quality rumen degradable protein, such as from soybean or canola meals.
This is because rumen bacteria grow better on plant protein, amino acids, and
peptides than on non protein nitrogen.
In our next lecture we will discuss how to make high quality hay and silage.
ello, my name is Alex Hristov and
I am professor of Dairy Nutrition at Penn State University.
In this lecture we will talk about Hay and Silage-Making.
Please also check Dr. Roth's lectures on dairy forages from an economic standpoint.
Before we begin this lecture, I must re-emphasize
the critical importance of forage quality for successful dairy operation.

There is nothing more important, from a nutritional viewpoint, for
a successful and profitable dairy farm than the quality of the forages.
In many production systems this quality can be controlled by preserving forages
or silage.
In pasture based or grazing systems, the quality of the pasture has to be
constantly monitored and managed, for example by rotational grazing,
to use maximum digestible organic matter per acre.
Farmers have preserved forages for their cattle for thousands of years.
The simple reason for doing this is to provide feed during seasons of the year
when fresh forages are not available.
Also, as mentioned in our previous lectures, the quality and
nutritive value of forages deteriorates as they mature, therefore,
an all important goal of preserving forages is to harvest them in their
optimal growth stage when they are the most nutritious.
How do you preserve forages?
The technology is simple and millenia old.


Open your pantry or the refrigerator in your kitchen, and
you are likely to see silage.
Well, not exactly the kind of silage we feed to diary cows.
But full preserved using the same process we use to make silage.
The two main process to preserve forages or dairy and
beef cattle, are hay silage-making.
When making hay, we are drying the material, usually in the field,
to a moisture level of about 12 to 18%.
First a malt at optimal maturity.
The wider the swath, the faster the hay will dry.
Then, as the hay starts drying in the sun, and reaches about 40 to 50% moisture,
It is tadded or raked to speed up the drying or curing process.

This has to be done at the right time and moisture to speed up curing and
minimize leaf losses as much as possible.
Particularly if the forage is alfalfa.
Alfalfa leaves have greater concentration of protein and
are more nutritious than the stems, so we don't want to loose too many of them.
Rain is enemy number one of good quality hay.
A rain event while the hay is on the ground
could cause up to 40% loss of plant nutrients.
Therefore, farmers are trying to time mowing and curing
of the hay with dry weather and then harvest the dry hay as soon as possible.
Plant cells continue to respire or burn energy in the form of sugars after mowing.
So, if the curing process is prolonged,
losses of valuable nutrients will increase.
Harvesting and storage are the last steps in hay making.
Hay is usually baled in small or large rectangular or round bales.
And could be stored under a shed or
wrapped in plastic for better preservation.
Moisture of baling is critical.
Usually target moisture is around 12 to 18% which will depend on the type and
density of the bales.
If the hay is too dry, field losses will be high.
If it's too wet, it will spoil upon storage.
To avoid this, start baling early in the morning when the dew is on the hay and
quit when moisture drops below 11, 12% particularly with alfalfa.
Another point that some farmers start considering is the fact that
plants photosynthesize and accumulate non-fiber carbohydrates,
usually sugars, during the day and then burn them at night.
Thus hay harvested in the afternoon has higher sugar content and
has been shown to be more palatable to animals than hay harvested in the morning.
This however has to be reconciled within increased leaf washes

if hay is harvested in the afternoon.
Once bailed, hay motion quality need to be monitored so
it can be efficiently included in rations for various categories of dairy cattle.
Now let's talk about silage.


In many intensive production systems, silage is the most important feed for
dairy cows.
Just like hay, the idea of making silage is to harvest the forage in its optimal
growth stage, preserve its quality as much as possible, or actually even increase it.
And have feed with relatively constant quality available throughout the year.
The salt process relies on bacteria producing enough lactic acid to bring
silage acidity, or pH down to levels usually below 5.
Which will depend on the type of silage.
Once this acidity is achieved, fermentation slows down and
eventually stops and the silage is preserved.
There are several important points to remember when making high quality silage.
First, where are the bacteria producing lactic acid in the silage coming from?
Usually they're already on the plant.
So, how much beneficial versus harmful bacteria are coming into the silage with
the harvesting the forage can determine the type of silage fermentation and
eventually silage quality.
The beneficial bacteria are the lactic acid producing ones.
These are the same kind of bacteria that ferment sauerkraut, yogurt, or cheese.
The undesirable bacteria are of various kinds but
some of the most harmful belong to a group called Clostridia.
These bacteria are commonly found in soil and
some produce deadly compounds such as tetanus and bodily toxins.
To promote beneficial fermentation farmers often use products that contain
lactic acid bacteria and our called silage inoculants.

These products are designed to speed up lactic acid accumulation and
some also help preserving silage quality when the silo is open.
We'll discuss innocuousy now in next lecture.
Another important factor is the type of forage to be ensiled.
Some forages are more difficult to ensile than others.
The main factors here are the buffering capacity of the plant.
Which is the capacity to buffer the lactic acid for used by microbes and
the plants sugar content.
Plants with high protein contents such as legumes,
who have high buffer in capacity and are more difficult to ensile than, for
example, grasses or corn and small grain silages.
Sugars are needed for the silage material to thrive and convert it into lactic acid.
This is the end of today's lesson.
We'll continue discussing silage quality in our next lecture.
Hello and welcome back.
We'll continue discussing the factors important for making high quality silage.
Apart from plant my crops and the type of forage we are [INAUDIBLE],
maturity at harvest, and forage [INAUDIBLE] or
moisture at the [INAUDIBLE] are also very important for silage quality.
The more mature the plant at the time of harvest the lower the digestibility and
energetic value of the silage.
Also more mature plants tend to have lower sugar content


which may slow down silage fermentation and prolong the time to reach optimal pH.
Dry matter of the forage in siling is perhaps the most important factor in
silage making.
The wetter the forage, the higher the fermentation rate, but
also fermentation losses.
Silage should not be made from forage that has 25% or less of dry matter.

When dry matter is between 30 and 25% or
lower, the use of silage preservatives such as organic acid is advisable.
Forages with dry method in siling around 40% can
be preserved well without any preservatives.
The higher the dry matter, however,
the more difficult packing the silage becomes, and losses may also increase.
For most silages,
the dry matter siling of around 32% to 40% will produce good results.
Another critical factor in silage making is packing.
It won't be an exaggeration to say that the first rule of silage making is pack,
pack, and pack again.
Packing is so important because most undesirable processes that
may take place in silage require oxygen.
Lactic acid bacteria, or the good bacteria in silage, on the other hand, hate oxygen.
So by packing the silage as much as possible will get rid of the air which
creates unfavorable conditions for harmful bacteria such as custrelia and
favorable conditions for the lactic acid producing bacteria.
The speed by which the silage is filled is also important.
Ideally a silo should be filled within three to five days.
In the real world the goal should be to fill a silo as soon as possible
while continuously packing the material that is already in the silo.
Having the right particle size of the forage entering the silo,
is a precondition for successful packing.
Recommendations for grass and
alfalfa silages are to harvest at theoretical length of cut of three-eighths
to half inch which is about 1 to 1.3 centimeters and for
corn silage at half to three-quarters inch, which is 1.32 centimeters.
The longer the cut and
the dryer the forage, the more difficult packing will be to get the air out.
Too short length of cut, however, is not going to provide the necessary effective

fiber to the animal, which may result in, and increased milk fat test.
Check the supplemental reading for this lecture for
a formula of how to calculate the density of your silage.
A good benchmark is 40 pounds
per cubic feet which is about 640 kilograms per cubic meter.
Another component of the siling process is silage preservatives.
There is a long list of silage preservatives on the market including
acids usually organic, for example, formic and benzoic acids.
Enzymes typically intended to digest plant fiber thus providing additional sugars for
fuel, silage fermentation, and microbial inoculants.


The later categories most widely used and typically contains
homolactic material designed to produce primarily lactic acid.
Recently silage inoculants also contained
bacteria called heteroactic that produce volatile fatty acids such as acetic and
propionic which help preserve the silage phase when the silo is open.
One important thing to remember about inoculants is that the viable microbial
count specified on the back label is not always representing accurately
the actual viable count that the inoculant will produce when applied to the silage.
As a rule of thumb,
inoculants should be supplying a minimum of 100,000 colony forming units.
Which is a measure of the number of viable bacteria,
of lactic acid bacteria per gram of wet forage.
Another type of silage that deserves mentioning, is urea,
or other non-protein nitrogen sources, such as anhydrous ammonium.
These are added usually to corn silage, which has raw protein content, for
two main reasons.
First, to serve as a preservative because ammonia inhibits bacteria and
second, to increase the silage protein content.

Remember that the rumen microbes can utilize non-protein nitrogen
to synthesize microbial protein.
Recommendations are for around eight to ten pounds feed grad urea per ton of wet
silage, which is four to five kilograms per metric ton.
Even distribution of the urea is important, and
the silage should not be too wet or too dry.
Less that 30 or above 40% dry measure.
Once the silage is in the silo and is packed well, it must be covered to prevent
air penetration, spoilage, and nutrient losses.
Some silage systems, such as tower silos, ag bags, or
wrapped bale silage, are protected from the air.
Bunkers or other type of open silos, however,
must be covered, usually with plastic sheets.
And then the plastic cover should be weighed down, usually with cut in half,
old automobile tires, or bags filled with sand and gravel.
Separate plastic sheets should overlap and
be taped, particularly around the silo walls.
If the silo is a bunker type or the base of the pile if it is a pile silage.
The cover should be inspected for leakage and
holes, particularly if in a windy place.
Newer plastic material such as oxygen barrier fumes have much lower oxygen
permeability than the regular polyethylene and
can reduce significantly silage losses.
To properly ferment, silage should be stored for
at least 30 to 45 days before being fed.
Silage fermentation may actually increase the energetic value of the original
forage, particularly true with corn silage.
However, feeding unfermented silage could cause decreased milk production.

Once the silo is open air and oxygen acts as the surface as the silage and
undesirable microorganisms such as yeast and molds start to grow.
Therefore managing the open silage surface is also very important
in order to insure the high quality of the silage the cow gets.
The key is to reduce exposure to air as much as possible.
This can be achieved by using various silage cutters, or block.
Or simply carefully moving continuous surface layer of the silage.
As a rule of thumb, a minimum of 6 inch, or
about 15 cm silage should be removed from the silo surface everyday.
And more should be removed in the summer.
Remember that any manipulation that leaves a pile of loose silage
will lead to high nutrient losses and poor quality silage.
Finally, when we start feeding new silage, we should always analyze it for
chemical composition to be able to more accurately predict it's notative value and
properly include it in the ration.
What are the most important silage quality analysis we should pay attention to?
The first one is silage pH.
It should be below four for corn silage and below 4.5 to five for legume silages.
Another one is lactic acid.
For corn and legume silages, the target is around 4 to 7% of the silage dry matter.
Butyric acid is an indication of clostridia fermentation and
should be very low, below 0.1%.
Or completely absent from good quality silage.
For legume silages,
which usually undergo extensive which is a breakdown of the plant proteins,
ammonia nitrogen should be less than 10% of the total silage nitrogen.
Here's an example of a lab report for chemical analysis of alfalfa.
The first thing to note is that the analysis was done by NIR or
near-infrared reflectance spectroscopy.
NIR analyses are considerably less expensive than wet chemistry, and

commercial laboratories have accumulated large spectral databases for common
feeds which is an important prerequisite for accuracy of this analysis.
Following the sample identification data, the first line in this report
shows dry matter content of the haylage, which is 46.2%.
Consequent analyses are usually interpreted on a dry matter basis.
Protein bases, as in the case with protein fractions.
This particular lab here structured the report into several categories,
including proteins, fiber, carbohydrates,
minerals, qualitative analysis, and energy and index calculations.
Some important analysis in the proteins category include crude proteins,
soluble protein, ammonia NAEF and
NDF protein both being proteins bound to fiber.
Rumen Degraded Protein is also an important indicator for legume forages and
is 83% of the total protein in this stage.
In the fiber category we find a couple different values for
neutral [INAUDIBLE] fiber.


The a in front of NDF means that the sample was treated with amalyse
enzyme to remove starch.
And the OM after NDF means that NDF is expressed on an organic meta basis.
In the carbohydrates category, it is worth noting the high soluble fiber value,
which can be calculated at around 38% of the neutral detergent fiber.
In this sample and represents pectins and other soluble polysaccharides.
Concentration of total ash and
important minerals are listed under the minerals category.
Note the high calcium and potassium content of this which is typical for
legume forages.
pH and silage acids are listed on the qualitative analysis.
Silage pH is below five,

which is an indication of good [INAUDIBLE] fermentation.
And lactic acid is above 4% of the dry matter,
which is within the goal of 4 to 7% for legume forages.
Being at the lower range is a reflection of the relatively high parameter content
of this scalage.
Note that this lab here stated that the NIR analysis is an excellent prediction
potential, which means that they have accumulated a large database for
alfalfa hayage and are confident in their prediction equations.
In the energy and index calculations we find calculated total digestible nutrients
or TDN and energy values for this haylage and other estimated foliage
characteristics such as relative feeding value and non fiber carbohydrates.
Overall, this slap analysis report indicates that our haylage is of a good
quality and reemphasizes the importance of knowing forage composition
before attempting to include it in rations for dairy cows.
This is the end of today's lecture, next we will discuss feed processing.
Hello, my name is Alex Hristov, and
I am Professor of Dairy Nutrition at Penn State University.
This lecture will talk about feed processing and
its importance in feeding dairy cows.
So why are we discussing processing of feeds?
The answer to this question is simple.
Because we want the cow to get as much energy and
other nutrients out of the feed we offer to her as possible.
It is important to remember that by processing,
most of the time we increase the energy value of feeds.
Other reasons for processing include improved palatability,
the reduced feed losses and better feed preservation.
With forages, we reduce the particle size by chopping the plant material so
the microbes in the rumen can access the digestible nutrients.
Microbial digestion cannot take place unless the microbes attach to the plant

particles.
They have to literally colonize the plant fragment to start the digestion process.
In nature, the cow will have to chew the roughage she consumes to
allow access of the rumen microbes to the plant tissues.


We help ruminants by doing some of the work by chopping forages for them.
They still chew their cud, which is very important for
producing enough saliva to buffer the rumen, but
processing decreases the energy expended for particle size reduction.
Keep in mind that a healthy cow with a normal dairy diet produces around
25 to 50 gallons, or 98 to 190 liters, of saliva everyday.
Particle size is very important for proper rumen function.
Penn State has produced the particle separator that is a simple device with
several sieves allowing evaluation of feed particle size.
The forage or ration sample is shaken for several minutes and
then the proportion of particles left on each sieve is weighed.
This table shows recommended particle size distribution for
a dairy total mixed ration and corn silage and alfalfa haylage samples.
Briefly, the top sieve will retain particles that are larger than 0.75 inch
or 19 millimeters, and are likely to promote chewing and salivation.
As particle size decreases from larger than 19 millimeters
to smaller than 4 millimeters, which is around 0.16 inch,
their chance to leave the rumen increases and
their function in promoting saliva production decreases.
Particle size distribution guidelines for corn silage, alfalfa silage, and
total mix ration and instructions how to use the Penn State particle separator can
be found in the additional readings for this lecture.
Wet or dry forages should be chopped to promote microbial colonization and
digestion.

The particle size guidelines outlined above and
in the earlier silage lecture should be followed.
It is important then the forage is not chopped too fine, because this will lead
to lack of effective fiber in the diet and may contribute to rumen acidosis.
Dr. Dave Mertons from the Dairy Forage Center in Madison,
Wisconsin, defined effective fiber, or eNDF,
as the overall effectiveness of the neutral detergent fiber in the diet for
maintaining milk fat test, and physically effective fiber, or
peNDF, as the specific effectiveness of neutral detergent fiber for
stimulating chewing activity.
Mertons calculated, for example, that physical effective fiber of soybean hulls,
brewers grains, corn silage, legume silage fine chopped or
legume silage coarse chopped, legume hay, and grass hay were 3%, 18%,
81%, 67%, 82%, 92%, and 98%, respectively.
What is important to remember here is that by-product feeds, such as soy hulls,
for example, may have high fiber content, 60% neutral detergent fiber.
But their effective fiber will be very low, only 3% compared with over 90% for
hay, because of their low ability to promote chewing and saliva production.
There are other treatments that can be applied to low-quality
roughages such as straw or corn stover.
These include treating the forage with alkali, anhydrous ammonia, or urea.
These treatments are intended to partially break down bonds between digestible fiber


and indigestible lignin, thus increasing the overall digestibility of the feed.
Additional benefit with ammonia or
urea, which will release ammonia when hydrolyzed during the treatment process,
is that the crude protein content of the forage will also increase.
This can be particularly beneficial with low-quality hays,
straw, corn stover or other high-fiber by-products.

The effect of anhydrous ammonia can be substantially enhanced if ammonia
is used under pressure and increased temperature.
Installations such as the one shown here combine liquid ammonia, pressure, and high
temperature to achieve up to 15% increase in wheat or barley straw digestibility.
Anhydrous ammonia can also be injected into bales covered with plastic,
as shown in this picture.
Next we will talk about processing grain.
If not chewed by the cow or somehow processed before being fed,
grain kernels can remain indigested in the rumen for
a long time due to the protective function of their seed coat or the pericarp.
Therefore, to facilitate digestion,
the seed coat of the grain kernel has to be at least damaged so
the microbes can penetrate and digest nutrients within the kernel.
For some grains that are less digestible, such as corn, for example, the extent of
processing is directly proportional to the extent and rate of digestion in the rumen.
The effect of processing on digestibility of grains such as barley and
wheat is small due to their inherently higher starch and
protein digestibility than that of corn and sorghum.
This means we can, to some extent, regulate digestion rate of grain,
particularly starch, by processing.
For example, if we would like to have a more rapid rate of corn starch digestion,
we would use a more aggressive processing such as fine grinding,
steam rolling, or steam flaking.
If our diet already contains a lot of digestible carbohydrates and we would like
to minimize corn starch digestion rate but still not lose starch in manure, we would
use a less extensive processing method such as coarse grinding for example.
We have to always keep in mind that fine-grinding
grain will increase its digestibility for dairy cows but,
depending on the overall diet, may also increase the risk of acidosis.
There are two types of grain processing, physical and thermal, or heating.

Physical processing is used to break the seed coat and
allow microbial access in digestion.
This kind of processing may also increase palatability of the grain.
Usually the advantage of physical processing is with small,
hard grains and for grains with thick seed coat.
Thermal processing involves temperature and usually also moisture.
Starch is heated, grain swells and gelatinizes.
The advantage of thermal processing is with less fermentable grains such as corn
and sorghum.
There are also other methods of processing such as roasting,


pelleting, extrusion, and micronization.
Thermal processing called heating usually involves steam.
The time of exposure to heat or
steam will determine the extent of starch gelatinization and its digestibility.
Steam-rolling, for example, exposes the grain to steam for
up to around eight minutes, and starch gelatinization is kept to a minimum.
With steam-flaking, on the other hand, grain is exposed to steam
up to 30 minutes and starch is gelatinized to a much greater extent.
Then the grain is rolled into flakes of varying thickness, which is also called
test weight, depending on the type of animal it's going to be fed to.
Gelatinization is proportionally related to digestibility because
the combination of moisture and
heat break down the intermolecular bounds of the starch molecules.
The starch granules absorb water, swell, and then burst, releasing starch.
Steam-flaking is perhaps the most extreme process of grain
that has the greatest effect on starch digestibility.
The decision to use one grain processing method over another,
however, has to be also based on cost of processing.

Processes such as steam-flaking are more expensive and
may not be justified under some conditions.
For example, with grains such as barley, or
when the diet already contains high levels of digestible starch or
corn silage with high proportion of grain harvested with a kernel processor.
Tempering is another grain processing method consisting of adding water to
the grain and allowing to soak for up to 24 hours.
This causes some swelling of the starch and increases digestibility.
In some cases a tempering agent is added.
These are surfactants, usually saponin-containing products,
which facilitates water penetration into the kernel.
The grain can then be rolled to different thickness depending on whether
it's going to be fed to beef or dairy cattle.
In our previous lectures, we discussed roasting of whole soybeans and
extruded soybean meal.
Both products are good sources of rumen bypass or rumen-undegraded protein,
and also provide extra energy as fat to the cow.
On this last point, the two feeds are quite different.
Whole soybeans have up to 19% fat and extruded soybean meal up to 10% fat.
More importantly, whole soybeans are less likely to affect fermentation in the rumen
because fat is released at a slower rate than fat from extruded soybean meal.
You may remember that unsaturated fatty acids such as those found in soybean and
other vegetable oils are more detrimental to the rumen microbes
than saturated fatty acids predominant in animal fat.
Whole soybeans are usually roasted to around 270,
320 degrees Fahrenheit, which is 130 to 160 degrees Celsius.
This is intended internal grain temperature,
and then further processed before being fed.

Fine grinding will increase protein degradability and
is therefore not recommended for roasted soybeans.
It is usually recommended that they are coarsely processed to halves and quarters.
There are different systems used to roast beans, such as drum roasters,
high-temperature air dryers, or open-flame roasters.
Independently of the process, temperature and heating and steeping time have to be
monitored to achieve desirable rumen bypass protein levels, but
also not overheat the beans.
The later may cause formation of indigestible [INAUDIBLE] products,
which will decrease intestinal digestibility of the soybean proteins.
Roasted corn or other grains such as barley and
wheat can also be fed to dairy cows.
Heating of the starch increases gelatinization and digestibility.
Roasting also produces caramelization of the sugars in the grain,
which enhances palatability and may increase feed intake.
Last we will briefly discuss extruded soybean meal.
A number of commercial extruded,
expeller soybean meal products are available on the market in the US.
The processes used to produce these meals vary, but
are generally based on the principle of pressing the beans with a screw press
which partially extracts the oil and creates heat by friction.
In the extrusion process, beans are first preheated in a dryer,
which prepares them for the higher temperature of the extruder.
This higher temperature cannot be reached if the beans are not preheated,
then moved to a receiver, and
finally pressed through a discharging die by high roast screw in the extruder.
Temperature is usually around 300, 320 degrees Fahrenheit, or 150 to 160 degrees
Celsius, and is regulated by adjusting the pressure through the die,
which increases or decreases the friction and the temperature of the extruded beans.
This is the end of today's lecture.

In our next several lectures, we'll discuss specifics of feeding lactating
cows at the various stages of their lactation cycle
Week 3
Latest Submission Grade
80%
1.
Question 1
Corn silage is fed to dairy cows because it is a good source of:
1 / 1 point


Energy

Digestible fiber

Digestible starch

All of the above
Correct
2.
Question 2
Compared with fiber in alfalfa, rate of digestion of fiber in grasses is usually:
1 / 1 point

Faster

Slower

Not different
Correct

3.
Question 3
Alfalfa forage is included in dairy diets as a source of:
0 / 1 point

Available protein

Energy

Fat

Phosphorus
Incorrect
4.
Question 4
Dry matter content of a good quality small grain silage should be around:
1 / 1 point

25

35


45

55
Correct
5.

Question 5
Whole roasted soybeans are a good source of:
1 / 1 point

Energy

Fat

By-pass protein

All of the above
Correct
6.
Question 6
Compared with other cereal grains, corn grain is a good source of:


1 / 1 point

Protein

Calcium

Beta-carotenes

Fat
Correct
7.
Question 7
Compared with corn grain, barley grain has:

0 / 1 point

More fiber

More protein

Less energy


All of the above
Incorrect
8.
Question 8
Nutritionists are cautious feeding wheat grain to dairy cows because of:
1 / 1 point

It's high starch degradablility

It's low protein content

It's high fiber content

It's low calcium content
Correct
9.
Question 9
Soybean meal is valued as a protein source for dairy cows because it’s protein is:
1 / 1 point

Mostly degradable in the rumen

Mostly undegradable in the rumen

Mostly true protein

Mostly non-protein nitrogen
Correct
10.
Question 10
Compared with soybean meal, canola (or rapeseed) meal has:
1 / 1 point

More energy

More methionine

Less fiber

All of the above