coursera week 4 DAIRY PRODUCTION AND MANAGEMENT

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 conditio

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

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 lectureHello, 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

Too much fiber in the diet

Too much fat in the diet

Too much protein in the diet

Too much starch in the diet

Milk protein content

All of the above

It stabilizes rumen fermentation

It is a good source of amino acids

Will depend on available facilities

All of the above

Correct

12.

Question 12

To properly formulate diets for dairy cows we need to know:

1 / 1 point

Animal requirements

Feed dry matter intake

Nutritive composition of the feeds

All of the above