coursera week 4 DAIRY PRODUCTION AND MANAGEMENT

Glossary
Abomasum: A compartment of the complex stomach of the ruminant animal, equivalent to the
stomach of monogastric animals
Body condition score: A management tool to determine the condition and nutritional needs of a
cow
Calorie: A unit of energy (in dairy nutrition, the unit for energy is Mcal, or 1 million calories)
Close-up period: Begins 3 weeks before calving and ends with calving
Dietary cation-anion difference (DCAD): Characteristic of the diet – typically, the difference
between the sum of two cations (potassium and sodium) and two anions (chlorine and sulfur)
Far-off period: Begins when the cows is dried and continues until 3 weeks before calving
Fresh period: Begins at calving and continues to 2 to 3 weeks after calving
Holstein-Friesian: Predominant breed of dairy cows in the US
Limiting amino acid: An essential amino acid that is most deficient in the diet of an animal and
limits milk production or growth
Macro minerals: Minerals, for example calcium, that are required in animal diets in larger
quantities (expressed as % of dietary dry matter)
Metabolizable energy (ME): Feed energy that can be directly used by the animal for
maintenance, work, or other productive purposes but also includes energy used for heat
increment
Metabolizable protein: Protein of feed, microbial, or endogenous origin that is digested and
absorbed in the small intestine
Micro minerals: Minerals, for example zinc, copper, selenium, etc., that are required in animal
diets in smaller quantities (expressed as parts per million, ppm, or milligrams per kilogram
dietary dry matter)
Multiparous cows: Cows in second and greater lactation
Net energy of lactation (NEL): Feed energy that can be directly used by the animal for
maintenance, work, or other productive purposes
Acid-detergent fiber: A chemical entity in feeds containing cellulose, lignin, and ash


Neutral-detergent fiber: A chemical entity in feeds containing hemicellulose, cellulose, lignin,

and ash
Non-protein nitrogen: Nitrogen that is in a non-protein form (i.e., amino acids, ammonia, etc.).
Can be used by the rumen microbes for protein synthesis
Omasum: A compartment of the complex stomach of the ruminant animal positioned between
the reticulo-rumen and the abomasum
pH: A quantitative measure of the acidity or basicity of liquids
Primiparous cows: First lactation cows
Reticulum: A compartment of the complex stomach of the ruminant animal (‘honeycomb’
structure)
Rumen: The largest compartment of the complex stomach of the ruminant animal
Rumen acidosis: Accumulation of volatile fatty acids and/or lactic acid in the rumen as a result
of extensive carbohydrate fermentation that brings pH down to levels critical for maintaining
microbial fermentation and animal health
Rumen-degraded protein (RDP): Feed protein that is degraded in the rumen
Rumen-undegraded protein (RUP): Feed protein that is not degraded in the rumen
Soluble fiber: A group of chemical compounds in animal feed, such as pectins and beta-glucans
Total mixed ration (TMR): A method of feeding dairy cows, in which all feeds are processed,
mixed, and then fed to the animal
Transition period: The period of 3 weeks before and 3 weeks after calving
Volatile Fatty Acids (VFA): End-products of microbial fermentation in the rumen that are the
major source of energy for the cow
hello my name is Alex Hristov and
I am professor of Dairy Nutrition at Penn State University.
Nutrition of dairy cattle is complex science and
feeding the cow is the single largest expense on the dairy farm.
Along with animal genetics, reproduction, health, cow comfort, and
management, nutrition is a piece of the puzzle for successful dairy farming.
In a series of video like this I will introduce you to the basics of proper
nutrition of lactating dairy cows.
We'll talk about the digestive physiology of the ruminant animal,

basic nutrients and the roll in ration, characteristics of feeds and


feed palate for dairy cows, diet formulation, and formulation programs.
First, let me introduce you to the most common feed terminology, which you have to
be familiar with to understand the principles of dairy nutrition.
Forages are the components of the dairy ration that provide fiber for
the proper rumen function and other nutrients to the ruminant animal.
Concentrate feeds are usually cereal grains or
oil seeds that provide energy and protein in the diet.
And by-product feeds are residues from various
food manufacturing processes that are used in animal nutrition
because they provide nutrients to our ration and may cost less.
Nutrients are a chemical compounds in the diet that serve different functions
in feeding the dairy cow.
Let's see now what type of nutrients are the most important in a dairy diet.
First we will focus on energy,
which is the most critical nutrient in the diet of any animal species.
Energy includes all nutrients in the ration
that fuel the engine of a dairy cow.
Energy can come from several sources, such as fiber, starch, sugars,
fat, and also from dietary amino acids.
By means of microbial fermentation in the fore stomach of the cow, feed energy is
converted into volatile fatty acids, abbreviated VFA and
microbial mass which both provide nutrients to the cow.
But to understand the process of microbial fermentation I need to first introduce you
to the anatomy and function of the digestive system of a dairy cow.
The cow is a ruminant animal like many other wild or domesticated ruminant
species such as sheep, goats, bison, elk, moose, camel or llama.
This is what the complex stomach of a cow looks like.

This vast space is called the rumen, the main organ responsible for
digestion of nutrients that cannot be digested by mammalian enzymes and
therefore by other farmers' species such as pigs and poultry.
It has a number of compartments separated by muscular folds.
The so called blind sacks are isolated from the main rumen and
contain feed particles for a longer period of time.
The rumen is scoured by papilla through which volatile fatty acids and
ammonia are absorbed into the blood stream.
Feed enters the rumen and
is sent back to the mouth for chewing through the esophagus.
The rumen is followed by the reticulum, then by the omasum, and
by the abomasum, which is a stomach similar in structure and
function to our own stomach and the stomach of a pig.
The abomasum empties into the small intestine and
the small intestine are followed by the large intestine.
Here you can see the honeycomb structure of the reticulum.
Particles that are small and heavy enough set here in these honeycombs.
And then are propelled through the omasal orifice into the omasum.
We have cut the omasum open here so


you can see the omasal leaves which squeeze the feed particles, absorb
water and minerals, and then deliver the digested particles to the abomasum.
The abomasum is an organ similar to our stomachs.
It produces pepsin Which is a a protolytic enzyme and the hydrochloric acid.
There is no microbial digestion in the abomasum.
The rumen is able to digest fiber because of its vast
population of different microorganisms including bacteria, protozoa, and fungi.
To better understand the rumen fermentation veterinarians surgically
prepare their animals with rumen cannules that will allow animal scientists to

sample and study the rumenal contents.
The procedures and care of cannulated animals are strictly controlled
by institutional animal care and use committees.
In the case of this cow that you see on this video,
the Pennsylvania State University Animal Care and
Use Committee approved all procedures used to place this rumen cannule.
Because of the veterinarian animal care, cannulated cows receive,
they usually live long productive lives.
Here is what the contents of the rumen of a dairy cow looks like.
Of the billions of microorganism in this handful of rumen digested,
bacteria are the most important players.
Just in this hundred or so grams of rumenal contents, there are over
a trillion bacteria in every imaginable form and shape that are responsible for
breaking down fiber and other carbohydrates and proteins the cow rumen.
In the next lecture we'll continue exploring rumen fermentation and
the fate of a major feeds nutrients in dairy cow ration
]
Welcome back.
In our last lecture we discussed rumen fermentation.
The vast populations of rumen bacteria are digesting feed to provide energy and
other nutrients for their growth.
The fermentation end products from this process are used by the cow for
her own energy and protein needs.
This symbiotic process is truly one of nature's wonders.
For example, bacteria ferment carbohydrates to volatile fatty acids, and
the cow is using the energy locked in these volatile fatty acids for
maintenance and new production.
Remember the law of conservation of energy, which states that energy can
be transformed from one form to another, but cannot be created or destroyed.
This will validate in the rumen of the cow as well.

In this example, carbohydrates such as cellulose, starch, and
complex saccharides are broken down to simple sugars and through pyruvate.
Rumen bacteria generate energy as adenosine tri-phosphate or
ATP, and volatile fatty acid such as acetate and butyrate.
Up to 75, 80% of the energy needs of the lactating cow are met
by the volatile fatty acids produced by rumen fermentation.


These volatile fatty acids are most important precursors for
the glucose needs of the cow.
In addition, lactate, originated primarily from the rumen,
glycerol from lipolysis of triglycerides in the adipose tissues, and
amino acids from intestinal absorption or
muscle protein breakdown, contribute to the total glucose needs of the cow.
Glucose absorbed from the intestine and
glucose released from the liver, mostly from glucolin genetics,
are the most important contributors to blood glucose levels.
Another important point to remember as we go to our nutrition lectures
Is that volatile fatty acids are acidic which means they can reduce Rumen pH.
PH is a quantitative measure of the acidity or
basicity of liquids in a scale of zero to 14.
PH is a simple but
very important measure used to gauge rumen fermentation and rumen health.
Normally rumen pH should be between six and
6.8 pH below 6.00 indicates too much acid production
by the microbes which leads to a condition called rumen acidosis.
Acidosis is usually associated with feeding too much grain or
highly fermentable feeds such as Russian grass high in sugars and
can lead to decreased feed intake and milk production, decreased milk fat
concentration, or more serious health conditions and naturally death of the cow.

So let's get back to the important topic of energy efficiency of dairy cows.
There are two types of feed energy, energy from the microbes in the rumen and
energy for the cow.
We have to very carefully manage the energy for the microbes so
we don't end up creating acidotic conditions.
This is best achieved by balancing fiber, starch, and sugars in the diet of the cow.
As it was already said, the energy source that fuel,
through various metabolic pathways, the life of a dairy cow consist of energy
from volatile fatty acids produced in the rumen.
Feed energy that bypasses the rumen is usually some undigested starch and fat.
And energy from body reserves such as adipose tissues or muscle proteins.
Proteins, specifically amino acids can be used as energy precursors for
synthesis of glucose.
By some estimates, amino acids could provide up to
twenty percent of the glucose needs of the ruminant animal.
Now let's see what is happening of the other major nutrient in dairy cow
nutrition, proteins.
When we talk about proteins we should know that similar to energy, proteins
are a required for both feeding the microbes in the rumen and feeding the cow.
Proteins per say are not nutrient.
The rumen microbes only utilize peptides, amino acids and
ammonia as building blocks for their cell proteins.
The rumen eco-system is so amazingly adaptable that the rumenant animal can
live entirely on mineral nitrogen from which the microbes can


synthesize amino acids that will keep the animal alive and well.
Back in the 60s, Artturi Virtanen, a Finnish scientist
demonstrated that dairy cows can live healthy and productive lives on diet
containing only non-protein nitrogen, such as urea an ammonium salts.

The cow however, needs amino acids for body functions and milk protein synthesis.
Feed proteins are commonly classified into two categories,
ruminally-degraded proteins, or RDP.
These are proteins that are degraded by the microbes in the rumen.
And ruminally-undergraded proteins, or RUP,
which are proteins that bypass the rumen without being nullified by the microbes.
The first type of proteins feed the rumen microbes contributing to microbial protein
synthesis, and the second provide amino acids to the cow directly.
The microbial protein synthesized in the rumen is the major source of amino acids
for the cow.
Making up 50 to 65-70% of the amino acid needs.
The remaining amino acids.
Divided by feed RUP.
The rumen microbes can not use proteins for self growth.
They have to first break down proteins into peptides, then amino acids and
eventually ammonia before they can utilize them.
It has been shown that most microbes have a preference for amino acids and
peptides over ammonia because it is an energetically more efficient process.
Ammonia is the preferred source of nitrogen for
the fibrolytic microbes in the rumen.
These microbes are extremely important for proper rumen function, and
therefore maintaining adequate ammonia concentration in the rumen is critical for
proper fiber fermentation.
Once protein is leaving the rumen from microbial or fecal region, region is
smaller this time, they're digested to amino acids by mammalian enzymes and
used by the cow for body functions and milk protein synthesis.
However, we have to have to be aware that not all RUPs digestible or
utilized by the cow.
Some RUP will not be digested in the small intestine and
will end up in feces, an undigested feed protein or

maybe converted into microbial proteins synthesize in the large intestine.
Fecal protein will be mostly of microbial origin.
In the next lectures, we'll talk about nutrient requirements, types of feeds and
principles of diet formulation
Hello, my name is Alex Hristov, and
I'm professor Dairy Nutrition at Penn State University.
As discussed in our previous lectures energy is the most important nutrient for
lactating cow.
Think of energy as the fuel you pump into your car which feeds the engine, and
allows the car to speed up the highway.
But just like the engine of a car can use only about 35% of the energy in gasoline


the cow can use only a fraction of a total or gross energy in feed stuffs.
Some of that gross energy will be washed in feces, some will be washed in urine,
some will be belched out with fermentation gases generated in the rumen,
some will be lost as heat merely to maintain body temperature and
for various body functions, and
finally after we take all of these energy losses out there will be energy left to
fuel the metabolic processes required to keep the cow alive and to produce milk.
This lost form of energy is called net energy or net energy rotation, and
it's abbreviated NEL, and is the unit used to define energy content feeds,
define energy requirements, and formulate that for dairy cows in the United States.
Some energy systems used metabolisable energy or ME as an energy unit.
The termination of MEF or metabolisable energy of feeds is a very difficult,
but necessary process if we are to accurately feed animals and
meet their energy requirements.
Different feeds depending on their qualities will provide
different amount of net energy to the cow.
For example, ground corn grain will have around 1.7 megacalories

net energy of lactation per kilogram.
Whereas alfalfa silage will have around 0.6 meta calories per kilogram.
Why the difference?
The difference comes from the fact that around 70% of the common grain
starch whereas the main energy carrying nutrient in alfalfa sage is fiber.
Around 30% of its dry method.
If we burn one gram of starch and
one gram of fiber they will produce about the same amount of gross or total energy.
The instrument shown here is an aerobatic bomb calorimeter,
and is used to measure gross energy content of feeds and other materials.
It is based on determining the heat of combustion of materials.
Let's do a small experiment.
We'll take the same amount of ground corn and
ground alfalfa silage, and burn them in the calorimeter.
Following the strict experimental protocol we have determined
that our grain has a coercing value of 6,867 BTUs per pound,
which after correction for dry method content and
conversion is 4.4 mega calories per kilogram.
The haulage has a coorig value of 7,478 BTUs per pound,
or 446 meta calories per kilogram.
Thus these feeds have very similar gross energy but
vastly different net energy of rotation content.
Another important point here is that we can calculate the coefficient of
conversion of gross energy to net energy, which for corn grain is 39%.
This is 1.7 divided by 4.4, and for
alfalfa silage is only 13% this is 0.6 divided by 4.6.
This difference represents the much greater losses of feed energy in feces,
rumen femernation, gasses, and
heat from fibrous feeds compared with starchy concentrates.

It also demonstrates the importance of using net or metabolizable energy for
formulating diets for ruminant animals.
The other important nutrient in dairy cow diets is protein.
The cow does not have requirement for protein per say, but for amino acids.
For convenience however, and because we have not refined the individual amino acid
requirements of dairy cows the way we have for pigs and poultry
we formula diets based on metabolism property, which I'll define here.
Proteins that are ingested with the feed undergo transformations in the rumen
before they reach the absorptive sites
in the wall of the digestive tract of the cow.
The sum of proteins that reach the small intestine and are further digested and
absorbed providing amino acids to the cow are termed metabolizable protein, or MP.
It consists of ruminally degraded proteins or
RDP, which we discussed in our previous lectures that is converted into microbial
protein, feed protein that has not been degraded into rumen or RUP, and
also endogenous proteins which originate from various endogenous sources such as,
cells from digestive tract, digestive enzymes, and other proteins secretions.
So what is a nutrient requirement?
Simply the lactating cow needs nutrients such as energine, protein to leave,
breathe, move, give birth to a healthy calf, and last but not least produce milk.
The cow has nutrient requirements or functions such as maintenance,
milk production, pregnancy only during the last trimester, and
growth particularly during her first rotation.
All these are combined to represent the nutrient command requirements for
a particular cow, or group of cows.
In the next lecture we'll further discuss nutrient requirements, and
I'll give you a specific example of how we calculate energy and
protein requirements of a lactating cow
Hello again.

Here we will continue our nutrient requirements lecture.
We formulate diets for
lactating cows based on their requirements which are mainly based on milk production
and composition, body weight, reproductive status and animal activity.
Anticipated or actual feed intake and
composition and costs of available feedstuffs.
Here's an example with a lactating dairy cow producing 40 kg/day of milk
with 3.8% milk fat and 3.2% true milk protein.
We'll assume that our cow consumes 26 kilograms feed of dry matter per day.
From simplicity we'll also assume that the cow is not pregnant and
does not grow anymore which means that her body weight is stable.
The requirement of net energy for lactation for this cow is 38.7
mMcal NEL/day, which approximately 29 Mcal are used for
milk production and 9 Mcal for maintenance.
The diet we formulate provides 39.8 Mcal per day,
which means it means the requirements of the cow for what they should.


It is about 103% of the requirements.
This same diet provides 3246 grams of metabolism protein.
Which about 1900 grams for milk production and 930 grams for maintenance.
The requirements for metabolizable protein for this cow are for 2842 grams per day
which means that our diet supply is about 404 grams metabolizable protein.
More than the cow requires for this level of milk production.
All this is counted in 14% of the requirements.
If, however, the cow does not like the diet we formulated, and
eats only 23 kilograms of dry matter per day, the balance of that energy
will be negative, about minus three Mcal per day and
the cow will likely be producing less milk then expected.
Similar to or amino acids the cow has requirements for

other nutrients such as macro and micro minerals and vitamins.
In the above example the requirement for calcium for
this cow it will be 67 grams per day while the diet supplies 91
grams per day or 24 grams above the requirements.
Other important minerals in the dairy cow nutrition are phosphorus, potassium,
sodium, magnesium, sulphur, zinc, selenium, iron, copper, and others.
We usually don't have a good knowledge of the vitamins contained in feedstuffs and
therefore we supplement the diet with the most important fat soluble vitamins
such as A, D and E.
It is assumed that the rumen microbes synthesize most if not all
water soluble vitamins such as the B complex vitamins and
their supplementation is not necessary.
Cow, as many other animals,
but not humans, can synthesize vitamin C for glucose in their liver.
Another important requirement for
all animals, but specifically dairy cows, is for fiber.
Although not all feeding systems have requirements for fiber
all dairy nutritionists are well aware of the importance of fiber in dairy diets.
Fiber is important because it keeps the rumen healthy, provides continuous supply
of energy to the rumen microbes, stimulates saliva production, and
keeps optimal pH in the rumen and helps maintain milk pass fat test.
We divide dietary fiber into fractions such as neutral-detergent fiber which
includes and and acid-detergent fiber which includes.
This division is based on chemical analysis and
both fractions contain an indigestible component called lignent.
In the above example, the diet we have formulated will have provided a total of
8.2 kilograms per day of neutral detergent fiber and
5.6 kilogram per day of acid detergent fiber.
In general in dairy nutrition,
neutral detergent fiber is considered a measure of feed intake limitation.

And acid detergent fiber and measure of diet digestibility.
Hello, my name is Alex Hristov, and
I'm Professor of Dairy Nutrition at Penn State University.


In our previous lectures we covered animal requirements, feeds, and feed processing.
It's time now to talk about how we feed dairy cows through the various stages
of their lactation.
Please also check Dr. Varga's lectures on dairy cow nutrition.
Formulating a diet for lactating cows is, as the saying goes, science and
art at the same time.
A good nutritionist or dairy manager will understand animal requirements,
feed composition and particularly forage quality,
interactions of feeds in the diet and nutrients in the rumen.
The nutritionist will also be aware of animal physiology and
health, farm economics, and environmental regulations.
This is the science part of feeding dairy cows.
The art comes with practical experience and the ability to make sense of
the multiple variables in a complex production system such as a dairy farm.
So as you see, it is simple.
First, I'll briefly explain the life cycle of a dairy cow,
and how her nutrient needs change during the lactation from parturition,
which is giving birth to a calf, to drying off.
The life cycle of a dairy cow starts as a calf,
then she's a heifer until giving birth and a cow throughout the rest of her life.
Please also check Dr. Varga's lectures on calf and heifer nutrition.
In intensive production systems such as the dairy systems in the United States,
where Holstein-Friesian or just Holstein breed makes up over 90%
of the dairy cattle, heifers are usually bred by artificial insemination at
around 15 months of age, when they reach live weight of around 390 kilos or

850 pounds, or about two-thirds of their expected mature body weight.
The gestation period in cattle is 280 days which is close to that of humans,
and Holstein heifers give birth to their first calf around 24 months of age.
These cows are called first lactation or primiparous cows, and
their lactation patterns and
nutrient needs are different than those of older cows, which are called multiparous.
After calving, cows are bred again, usually within 80 days, and
conceive on average around 140 days after calving.
Ideally cows will give birth to a calf every 12 to 13 months, but
in the US target calving interval is around 14 to 15 months.
Dairy cows are usually milked for 10 months, which is about 305 days, and
then they get a break of 50 to 60 days before calving and
starting another lactation cycle.
Cows in the US have an average life span of 2.4 to 3 lactations.
Cows in larger herds and more intensive production systems
tend to have shorter productive lifespans than cows in smaller herds and
extensive such as pasture production systems.
The feeding program of a dairy cow changes according to her nutrient
needs during the various stages of the lactation cycle.
Terms that we use to describe these stages include far-off period, which begins
when the cows are dried and continues until three weeks before calving.


Close-up begins three weeks before calving and ends with parturition.
Fresh period begins at calving and
continues to two to three weeks after calving.
Dr. Varga covered the far-off and
close-up stages in her dairy cow nutrition lectures.
In this lecture we'll discuss feeding fresh and lactating cows.
The period of three weeks before and

three weeks after parturition is commonly referred to as transition period.
As shown in this figure, milk production sharply increases after parturition,
reaches peak lactation between 40, 70 days, and
then steadily declines until the cow is dried off.
Feed intake, however, decreases sharply before calving and
cannot catch up with milk production until 120,
140 days after parturition, and the cow is in a state called negative energy balance.
From a nutritional standpoint, this is important because the diet during this
period should be formulated to minimize the impact of negative energy balance on
milk production, animal health, and reproduction.
This negative energy balance is the reason cows lose body weight in early lactation
as they use body reserves to fuel milk production, and
then compensate the loss in mid and late lactation and the dry period.
It is normal that cows lose up to half body condition unit
on five unit scale during this period.
This chart gives you a good idea of the body condition scoring system used in
the US.
You can also find it in the supplemental materials for this lecture.
Milk composition changes during the lactation, and
this should be also considered when formulating diets.
Concentration of all milk components is much higher during the first several, four
to five, milkings, including the colostrum period, which is one to two milkings.
Gradually it decreases to lactation week eight, and then levels off and
slightly increases as milk production decreases in late lactation.
In most dairies, nutrition and grouping of the lactating herd go hand in hand.
There are various recommendations as to how to group cows, which consequently
plays a role in how many rations are formulated and fed to the herd.
The decision to implement one grouping or
feeding strategy versus another comes down to economics, which is cow comfort and
milk production versus available facilities and labor.

Where facilities allow it, first lactation cows should be separated from the older
cows, and usually stay separated throughout most of their first lactation.
The older second and greater lactation cows can be grouped based on days in milk,
which usually reflects their milk production.
For example, a fresh group, up to 20-30 days in milk.
A high group or high producing cows, between 20-30 to 100 days in milk.
A mid group, 100 to 200 days in milk.
And a low group, above 200 days in milk.
Probably a more common grouping strategy is to have two lactation groups, high and


low producing cows, in addition to a fresh group,
which means formulating three diets for the lactating herd.
Any grouping in any dairy farm will be composed of cows
with different milk production, nutritional needs, and social behavior.
Therefore, group feeding is a compromise between meeting the nutrient needs of all
cows and the practicality of delivering nutrients in bulk to reduce labor and
feed costs.
Feeding cows as a group inevitably will lead to overfeeding some cows and
underfeeding others.
Cows partially compensate for this by varying their feed intake.
For example,
high-producing cows will eat more of the same ration than low-producing cows.
Also nutritionists will use so-called lead-factors to assure
that the higher producing cows in a group are not underfed.
As an example, instead of formulating for the average milk production in a group,
they will formulate a ration that is 15% or
more above the average group milk production.
So what do we need to formulate a diet for a lactating dairy cow?
First we need to have a good handle of the nutrient requirements of the breed of

cattle we are working with, their specific body weight, milk production and
milk composition, physical activity, for example,
walking distance to be milked or fed, weather, and pregnancy status.
Requirements will change depending on all of these factors.
For example, in addition to volume of milk produced, concentration of fat,
lactose and protein in milk will have a large impact on nutrient requirements.
The higher these components are, the higher the requirements for
net form metabolizable energy and or metabolizable protein would be.
Second we need to know, or at least have a pretty good idea of,
what the dry matter intake of the cows is or would be.
Remember that we may formulate diets various ways.
But what matters to the cow is how much of one or another nutrient she consumes.
So without an accurate estimate of dry matter intake, we will be off with our
prediction of animal response to the diet we have formulated.
Note that I am using the term dry matter intake.
This is because we formulate diets for
dairy cows and other cattle based on the dry matter of the diet.
Water is an important nutrient, but
it does not provide any energy or protein to lactating animal.
Therefore, when the diet contains wet feeds such as silage, we have to calculate
the nutritive value of that feed and its inclusion rate on dry matter basis.
Having accurate estimates of dry matter intake of the cows in a herd
also allows calculating the efficiency of conversion of feed into milk.
The formula for this is simple.
Amount of milk divided by the amount of dry matter intake.
It's also called feed efficiency or milk efficiency.
A good benchmark for this is 1.5 and above.


This means on average the cows are producing 1.5 pounds or

kilograms of milk per pound or kilogram of dry matter intake.
Efficiency below 1.5 is indicative of a problem along the production line and
should be investigated.
Finally, in addition to animal requirements and feed dry matter intake,
we need to know the nutrient composition of the individual feeds and
the entire diet.
Forages should be analyzed regularly, weekly, once a month, or
when opening a new silo, for dry matter content and chemical composition at least
crude protein, fiber fractions, starch if it's a corn silage, and major minerals.
Table values for chemical composition of most concentrate feeds such as corn grain
or soybean meal, are used for diet formulation purposes.
For most byproducts, for example distiller's grains or bakery by-product
meal, nutrient specifications provided by the manufacturer are usually
a reliable source of information for chemical composition of these feeds.
Bottom line is, without any of these three components,
animal requirements, dry matter intake, and feed nutrient composition,
we cannot properly formulate diets for lactating cows.
Generally, nutritionists strive to meet the energy requirements of the cows first.
Energy is directly related to digestibility of the diet, and
any poor-quality, low-digestibility feed, these are usually the silages in the diet,
can have a dramatic impact on the energy content of the entire ration.
Forages, starch from grains, and oils are all sources of energy for the cow.
Fiber, starch, and sugars are also energetic sources for the rumen microbes.
The diet should exceed the calculated energy needs of the animal.
For example, if the requirements for
net energy of lactation of an average cow is 40 mega calories per day,
it will be appropriate, particularly for feed a group of cows,
to formulate a diet that would provide 44 mega calories of net energy per day.
As part of this process we balance the energy sources in the diet.
For example, our target for neutral detergent fiber should be around 30% of

the dietary dry matter or 1.0%, 1.2% of the cow's body weight.
Much higher fiber content will decrease energy intake due to rumen fuel
limitation, and much lower fiber content will lead to digestive disturbances due
to lack of effective fiber to maintain salivation and rumen function.
Do you remember what effective fiber is and
what are the feed sources of effective fiber?
If we have all fiber in the diet coming from soy hulls, for
example, this will not be effective fiber.
Therefore, we usually target around 75% of
the dietary neutral detergent fiber to be from forages.
Starch should usually not exceed 25% of dietary dry matter.
This number will depend on the type of starch and processing and
also quality of the forage in the diet.
Please check the feed processing lecture for this information.
I usually also pay attention to the non-fiber carbohydrates


fraction in the diet.
This is a calculated number and usually represents mostly dietary starch, but
will also include sugars and oligosaccharides, such as fructans, and
soluble fiber, such as pectins and beta-glucans.
Recommendations for
non-fiber carbohydrates are around 40% of dry matter and should not exceed 45%.
Some nutritionists and formulation programs also look at total rumen
fermentable carbohydrates, which is a better estimate, when it's accurate,
of the energy available to rumen microbes.
The last energy component of the diet is fat.
Total fat in dairy diets should not exceed 6% to 7% of dietary dry matter.
In certain circumstances such as hot weather or early lactation,
when total feed intake may be depressed,

fat can be cautiously increased to increase the energy density of the diet.
With fat from feeds in the diet being 3% to 4% supplemental fat,
should be in the range of 3 to 4% maximum.
At the upper level of this range, supplemental fat should come from
rumen-inert sources, which is fat that is protected from rumen degradation and
supplies digestible fatty acids through the small intestine.
Here's a summary of common feed energy sources in a dairy diet.
Good sources of effective and functional fiber for dairy cow diets are country
specific, but for the US include high-quality forages such as alfalfa or
grass hay, and grass, corn, or small grain silages.
Good sources of rumen-fermentable and soluble fiber are soy,
cottonseed, almond hulls, sugar beet, and citrus pulp, and
combination feeds such as whole cottonseed.
Good sources of starch are cereal grains, with processed corn grain and
barley being the most widely used.
Good sources of rapidly fermentable energy for
the rumen microbes are molasses, sugar beet or cane, almond hulls and
various by-products of the bakery or candy industries.
A good source of fat that is not going to be too detrimental to the rumen microbes
is whole roasted soybeans.
We'll continue discussing the specifics of diet formulation in our next lecture
Hello, and welcome back.
We continue our lecture on formulating diets for lactating dairy cows.
In our last lecture, we talked about balancing dietary.
While the diet meets the energy and fiber needs of the cow,
we continue balancing it for the second most important nutrient, which is protein.
Although metabolizable protein is the proper unit for using diet formulation for
dairy cows, crude protein is still widely used by nutritionists in the field.
Normally, dairy diets range in crude protein from 15, 16 to 17, 18%.
If for example the total crude protein in a diet is 16%, around 10% should

be as rumen degraded protein, and the remaining 6% as rumen undegraded protein.
Nutritionists also pay attention to protein solubility,
which is a relatively easy and accurate laboratory analysis.


A good target for soluble protein is about a third of the total dietary protein.
As indicated in our previous lecture,
gramatine intake a is a critical part of protein nutrition as well.
We cannot meet protein requirements of the cow if the ramen intake
is not accounted for in estimating protein supply.
One important factor to consider when formulating dietary protein
is its effect on the environment.
This will be discussed in the end of this course.
Nutritionists are increasingly paying attention to balancing amino acids for
dairy cows.
There are several amino acids that are important in lactating cows,
referred to as limiting amino acids, because their deficit
could potentially lead to decreased milk production or milk protein yield.
These amino acids are methionine, lysine, and histidine.
Balancing for amino acids becoming more important when dietary protein
levels are relatively low, for example below 17% good protein.
Methione is considered the most important amino acid in North American dairy diets.
Target concentration should be around 2.2% of the metabolizable protein.
What this means is that the normal diet which is
around 10-11% metabolizable protein on the dry matter basis,
should have methionine concentration of around 0.23% of dietary dry matter.
Lysine is also an important amino acid for dairy cows, particularly in corn based
diets, because its low concentration in corn and other cereal grains.
Target dietary level is around 6.6% of the metabolizable protein.
Histidine is the third amino acid to identify thus limiting milk

production in dairy cows.
Its target concentration in metabolizable of protein should be around 2.2 to 2.4%,
or similar to that of metianine.
Amino acid analysis are expensive and rarely performed in the field.
This means that nutritionists have to rely on tabular data, which brings
a significant uncertainty particularly with forages and by-product feeds.
It's also to point out that synthetic rumen protected amino acids are commonly
supplemented to dairy diets in intensive production systems.
For these products, it is important that accurate room and bypass and
intestinal digestibility specifications are provided by the manufacturer.
Good sources of rumen-degraded protein in dairy diets include soy, canola,
and sunflower meals, alfalfa forages or
dehydrated meal, and in certain situations, plain or
slow release urea products, particularly with well producing cows.
Good sources of rumen-undegraded protein include heat treated oil seed meals,
whole roasted soybeans, corn gluten meal, blood meal, and
animal proteins where are allowed to be fed to ruminants, and
to some extent by-products of the ethanol industry, such as distillers grains.
In general, all animal protein and
fish meals will be high in limiting amino acids.
Good sources of Lysine are a dehydrated alfalfa meal, soy and


canola meals, fish and blood meals.
Good sources of Methionine are corn grain, and corn by products such as corn
gluten meal, sunflower meal, fish meal, and to some extent canola meal.
A good source of Histidine is blood meal.
With all protein supplements, it is important to know the intestinal
digestibility of their rumen-undegraded protein.
Excessive heat generated during processing, for example,

will render rumen bypass protein and amino acids indigestible in the small intestine.
As a rule of thumb, various protein feeds provide different amino acids to the diet,
and where possible, the diet should include more than one protein source.
After balancing the diet for energy, fiber, protein fractions and amino acids,
the next step is to meet the mineral and vitamin requirements of the cow.
Usually the minerals and
vitamins in a dairy diet are supplied to a mineral vitamin premix, manufactured by
the feed company, based on specifications provided by the farm nutritionist.
The mineral vitamin primerl sandring can be included separately in the diet or
in combination with other feed's, usually protein, and
in some cases fat supplements.
Important macro minerals in daily diets include calcium, phosphorous,
magnesium, sodium, from salt, and potassium.
Acceptable for potassium, dairy diets are usually supplemented
with micro minerals to meet the requirements of the cow.
Another exception may be phosphorous,
which is a nutrient of environmental concern, and may be in excess
if the diet contains large amounts of cereal grains and by-products.
The macrominerals are also important for maintaining the body acid-base balance,
and are used to calculate the cation-anion difference of the diet, which is DCAD.
Requirements for a number of microminerals are also specified in dairy diets, but
nutritionists usually are mostly concerned with meeting the IMO requirements for
copper, zinc, manganese, and selenium.
Typically dairy diets are supplemented with the fat soluble vitamins A, D, and E.
Please read the supplemental material for
this lecture for more detailed information on mineral and
vitamin nutrition of dairy cows, including dietary cation-ion difference.
Here are a couple of examples of typical lactating cow diets from the eastern and
western United States, Pennsylvania and Idaho.
Note the high inclusion rate of corn silage in the Pennsylvania diet, and

the alfalfa hay in the Idaho diet.
This reemphasizes the point that foragers used in dairy diets
are going to be locally produced, and therefore region specific and
concentrate feeds will be more or less common across the industry.
Also here's an example of typical chemical composition of dairy diets fed to
high producing, over 30,000 pounds or
13,000 kilograms of milk per lactation, dairy herds in the US.
Note the high level of dramatine intake up to 26 kilograms per day.
The relatively moderate quick-protein concentration, the neutral detergent fiber


concentration being around 30%, and non-fiber carbohydrates being around 40%.
Total fat in these diets did not exceed 7% of dietary gramat.
Now we will briefly discuss some recommendations for
the various stages of the lactation cycle.
Specific recommendations for fresh cow diets include feeding a small amount, two
to five pounds or two to two and a half kilograms per day of high quality long or
chopped if a TMR is fed, grass or alfalfa hay or straw to maintain lumen function.
Feed intake is depressed in this stage of the lactation.
And increasing the ration nutrient density is recommended.
This have to be done cautiously because cows in this stage
are most susceptible to digestive disturbances.
Inclusion of rumen-degraded fiber sources such as soy house, is also recommended.
Grains with rapidly digestible starch such as wheat or barley should be avoided.
If fat is supplemented to the diet,
it's recommended that it is in a ruminated form.
Total dietary proteins should be kept at around 18 to 19%, and
the diet should contain increased amounts of high quality feed and degraded protein.
For example, a 680 kilograms or 1500 pound cow milking 35 kilograms or
77 pounds per day, would require about 2200 grams

of metabolizable protein, which is about 19% crude protein on dry matter basis.
Fresh cows should be housed and fed separately from the rest of the herd.
With enough feed bunks space if it's a free stall bunk, and
fresh water available at all times.
In early lactation, up to 100 days in milk, cows will be losing body weight.
Therefore maximizing dry matter intake during this period is critical.
Every effort should be made to provide palatable feeds and
avoid feeds, that may decrease dry matter intake.
Forage quality and digestibility feed processing, frequency of feeding,
consistency of the ration ingredients,
are all important factors affecting dry matter intake in this period.
Here's a simple way of estimating dry matter intake of your cows.
Multiply the body weight of an average adult cow, by 0.02 for
2% and add 25% of the average milk for the group.
In this example, a herd milking on average 80 pounds, with average body weight
of 1400 pounds, should have a minimum dramatine intake of 48 pounds,
which is around 2200 kilo [INAUDIBLE] per day.
A more complex equation to predict dry [INAUDIBLE] intake based on cow body
weight, milk production, and
stage of the lactation can be found in the supplemental materials for this lecture.
The diet should contain at least 45 and preferably 50% forage on dry matter basis.
Crude proteins should be around 17%, although a well
balanced diet with 16% crude protein will also produce good results.
About a third of the dietary protein should be ruminary un-degraded.
Feeding frequency is usually once or twice a day.
Feed should be pushed as frequently as possible, six or more times daily.
Cows like fresh feed and will eat the most when fresh feed is first delivered and


after milking.

Pushing the feed also stimulates feed intake.
Dietary changes should be avoided and implemented gradually when necessary, for
example if concentrate inclusion is increased.
In mid-lactation, 100 to 200 days in milk, cows have already reached peak milk
production and drimine intake, and are not losing body weight.
The goal in this stage is to maintain peak milk production as long as possible.
Forage quality is again the most important factor in the diet.
Digestible fiber could gradually replace some of the dietary starch, and
good protein concentration can be reduced to around 16%.
The proportion of forage in the diet can be increased to 60% or more.
Driamine intake is still critical.
Cows are a breath during this period, and
improving their energy status is important for success of the reproductive program.
In late lactation, which is above 200 days in milk, cows continue to gain weight, and
their milk production decreases.
The quality of the dietary sources of energy and
protein are not that critical in this stage of the lactation.
Protein concentration of the diet can be further decreased to around 14-15%.
And non protein nitrogen sources can be included.
Diets can be formulated with cheaper feeds, and
greater proportion of forages to avoid over conditioning of the cows.
Now a few words on diet preparation.
Most dairies in the US deliver feed to the cows as total mixed ration, or
TMR, which is all processed feeds mixed together and fed to a group of cows.
Advantages of TMR include consistent delivery of a balanced ration,
which results in a more stable rumen fermentation, and
increased microbial protein synthesis in milk components, reduced labor, and
improved accuracy of nutrient delivery.
The biggest disadvantage of feeding TMR
is that cows cannot be fed based on their individual needs.

And also that it requires expensive feed-mixing equipment.
There are two basic types of TMR, mixes vertical and
horizontal, with different configurations and models within each category.
Although some reduction in particle size occurs during mixing,
a more important consideration should be the uniformity of the mix.
It is recommended that mixing times between three and six minutes.
TMR preparation guidelines are provided in the supplemental material for
this lecture.
Dry matter intake of the forages in a dairy farm constantly changes, and
should be monitored on a weekly basis, at least twice monthly.
And corrections to the ingredient composition of the TMR should be made
when necessary.
Target dimethyl content of the diet should be around 48 to 52%.
To assure maximal dymeth intake,
TMR should be offered to result in about 3 to 5% refusals.


This means that no less than 3% of the feed
should remain in the feed bunk prior to feeding the new TMR.
Attention should be paid to sorting, the particle size of the refusals and
the fresh TMR, should look like more or less the same.
Sorting can occur when forages are not properly processed and should be avoided.
Check the feed processing lecture for recommended TMR and
forage particle size distribution.
The above recommendations are for feeding TMR.
When forages and concentrate feeds are fed separately, sometimes called component
feeding, the following recommendations should be considered.
Concentrates should be fed after the forages and several times during the day.
As with TMR, feed should be available to the cows at all times.
Usually, it is preferred that energy and protein concentrates are combined.

When two or more forages are fed, they should be mixed and fed together.
For the remaining materials on component feeding of dairy cows
are provided in the supplemental literature to this lecture.
Finally, we should always remember that feed is the largest expense on a dairy
farm, and nutrition of the cow is the most important component of
a dairy production system, directly affecting milk production and composition,
animal health and reproduction, and overall farm profitability.
This is the end of the dairy nutritional segment of our course.
Next, you will be introduced to dairy cattle reproduction
Week 4
Latest Submission Grade
100%
1.
Question 1

The main organ of the digestive tract of a dairy cow is:
1 / 1 point

The rumen

The omasum


The abomasum

The reticulum
Correct
2.
Question 2

Digestion of fiber in the rumen is carried out by:
1 / 1 point

Bacteria

Protozoa

Fungi

All of the above
Correct
3.
Question 3

Which of the following is the main source of energy for the dairy cow?
1 / 1 point

Glucose


Amino acids

Volatile fatty acids

Glycogen
Correct
4.
Question 4

Rumen acidosis is usually associated with:

1 / 1 point

Too much fiber in the diet

Too much fat in the diet

Too much protein in the diet

Too much starch in the diet
Correct
5.
Question 5

Which of these compounds can serve as a source of nitrogen for the rumen microbes?


1 / 1 point

Amino acids

Peptides

Ammonia

All of the above
Correct
6.
Question 6

Modern feeding systems use which type of energy to formulate energy requirements for dairy

cows?
1 / 1 point

Net energy

Gross energy

Digestible energy

All of the above
Correct


7.
Question 7

The dairy cow has nutrient requirements for which functions?
1 / 1 point

Milk production

Maintenance

Pregnancy

Growth

All of the above
Correct
8.

Question 8

Important factors determining the nutrient requirements of dairy cows are:
1 / 1 point

Milk production

Milk fat content


Milk protein content

All of the above
Correct
9.
Question 9

Fiber in dairy diets is important because:
1 / 1 point

It is a cheap source of energy

It is available locally

It stabilizes rumen fermentation

It is a good source of amino acids
Correct
10.
Question 10

Usually, cows are milked for how many days in a year?
1 / 1 point


Around 305

Around 365

Around 205

Around 405
Correct
11.
Question 11

Commonly, in a dairy farm cows are grouped based on:
1 / 1 point

Lactation stage

Milk production

Will depend on available facilities

All of the above
Correct
12.
Question 12