Detecting Estrus

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En provenance du cours de The Pennsylvania State University

Dairy Production and Management

345 notes

The Pennsylvania State University

Dairy Production and Management

345 notes

With the world's first MOOOOO-C, you will gain a broad and comprehensive understanding of all aspects of dairy management such as genetics, nutrition, reproduction, animal health, farm economics, and sustainability of dairy production systems. There's something here for everyone whether you are just looking for the basics or have years of experience in the dairy industry. This is an eight-week course. Each week consists of four to nine video lectures, additional reading materials, and a multiple-choice questions quiz. Estimated study time is between three and five hours per week. Learners have the option to purchase a Course Certificate for 49.00 USD. The certificate can be purchased at any time, but you must verify your identify before taking the course quizzes in order to be eligible. For those who cannot afford the certificate fee, financial aid is available through Coursera. Why is producing milk efficiently and sustainably so important? Milk provides humans with over 16 essential nutrients, such as: Energy, Protein and Essential Amino acids, Vitamin A, Vitamin D, several B vitamins, including B12, Pantothenic and Folic acids, and essential minerals such as Calcium, Magnesium, Phosphorus, Potassium, Zinc, as well as other minerals. Did you know that one glass of milk provides a 5-year old child with 21% of his/her daily protein requirements and 8% of their energy needs? Most milk in the world, about 85%, is produced from cattle. However, water buffaloes, goats, sheep, and camel are also dairy animals. The United States, India, the European Union, Brazil, and New Zealand are among the largest dairy producers in the world. Yet among these dairy-producing countries there are varied methods to generate milk with highly variable productivity and efficiency. Dairy production is vital for the survival of billions of people. Globally, around 150 million small-scale dairy households, equivalent to 750 million people, are engaged in milk production. The number and size of dairy farms varies among countries, but in India alone, there are estimated 78 million dairy farms! In the United States, one of the leading milk-producing countries in the world, total milk production has been steadily increasing in the last decades, reaching over 205 billion pounds (93 billion kilograms) in 2014. This was accompanied by a steady increase in average milk yield per cow, reaching 22,260 lb (over 10,100 kg) per lactation in 2014. How has this efficiency been achieved? What methods are necessary to ensure production of high quality milk? How do we balance milk production efficiency with animal health and environmental protection? This course will provide the student with information to better understand dairy production systems and their role in feeding the world population. In this MOOOOO-C, you will learn about the dairy enterprise from internationally recognized dairy science professors who have delivered highly regarded dairy education programs within the United States and internationally. Course lectures are translated into Portuguese and Chinese; PDF files of these translations can be found under each course week. The Dairy MOOC team thanks Dr. Antonio Branco (Universidade Estadual de Maringá, Brazil) and Ms. Yuanyuan Zhang (Pennsylvania State University) for translating the lecture materials. Course Sponsors This course was supported by the generous contributions of Innovation Center for US Dairy at Silver Level and Pancosma North America, RP Nutrients, Inc. and Arm and Hammer, which provided funding support at a Bronze Level. The Pennsylvania State University has final responsibility for the academic content of this course.

À partir de la leçon

Dairy Reproduction

This week you will learn basic concepts related to reproduction on dairy farms. We will start with a discussion of the life cycle of the dairy cow and how to adequately prepare a heifer for her fist calving. Next will be a discussion of the basic anatomy and function of the male and female reproductive tracts. This will be followed by an overview of the bovine estrous cycle and the main hormones and ovarian structures that control the cycle. We will follow this with a discussion of factors controlling the expression of estrus by dairy cows and how to be more effective at detecting estrus. We will highlight the critical need to time ovulation and insemination to maximize conception rates and will discuss some of the factors which reduce conception rates. This will be illustrated by a discussion of the key reproductive metric, pregnancy rate. Viewers will learn about strategies to increase pregnancy rates and will better understand methods used for pregnancy detection along with the critical need for early and accurate pregnancy detection to maximize the farms’ pregnancy rates. Those of you, who would like to get more engaged in discussions and are interested in completing the Course Certificate requirements, can participate in discussion forums and take the weekly quiz. Enjoy this week's material and the entire course!

Birth to Puberty7:13

Female Anatomy10:06

Male Anatomy9:31

The Estrous Cycle9:27

Detecting Estrus9:26

Conception Rate and Pregnancy Detection10:37

Rencontrer les enseignants

Alexander N. Hristov
Professor of Dairy Nutrition
Animal Science
Troy L. Ott
Professor of Reproductive Biology and Associate Director
Huck Institutes of the Life Sciences
Bhushan Jayarao
Resident Director
Penn State Animal Diagnostic Laboratory (ADL)
Greg Roth
Professor of Agronomy
Plant Science
Gabriella A. Varga
Distinguished Professor of Animal Science
Dairy and Animal Science
Chad Dechow
Associate Professor of Dairy Cattle Genetics
College of Agricultural Sciences
Robert Van Saun
Professor of Veterinary Science and Extension Veterinarian
Department of Veterinary and Biomedical Sciences
Kathy Soder
Research Animal Scientist
USDA-Agricultural Research Service, Pasture Systems and Watershed Management
James Dunn
Professor of Agricultural Economics
Agriicultural Economics, Sociology and Education
Lisa A. Holden
Associate Professor of Dairy Science
Animal Science

[MUSIC]

Hello, now that you know a bit about the estrus cycle of the cow,

let's focus on challenges of detecting estrus or heat, and inseminating cows at

the appropriate time to maximize the chances of establishing a pregnancy.

Heat detection is important in the US,

because the majority of cows are bred by artificial insemination.

Remember from our discussion of the life cycle of the cow, after she calves,

we give the cow roughly two months to adjust to the demands of lactation and

to heal her uterus in preparation for the next pregnancy.

We want cows to calve roughly every 12 to 13 months for profitable dairy production.

In order to accomplish this, dairy farmers must be good at detecting estrus.

However, there is a wide variation in the ability of dairy workers to

accurately detect heats, and in many cases,

they will detect less than 50% of heats in their herds.

Even worse, in some cases, cows are called in heat that are not in heat.

When this happens you not only lose time, but

money is wasted on insemination that will not result in a pregnancy.

This can be a real problem for getting cows pregnant in a timely fashion.

Now, if the farm uses bulls to breed the cows,

heat detection is done by the bull, which is housed with the cows.

Bulls are generally considered to be much better at detecting heat

in cows than humans are, which should be no surprise to anyone.

So you might be asking, well, if heat detection is so difficult for humans and

bulls are so good at it, why not just use bulls to breed all the cows?

Well, there are a number of reasons why bull breeding is not desirable.

First and probably most important, is that a farm's ability to improve the genetics

of their cow herd will be reduced if they use bulls for breeding.

Adoption of artificial insemination

has allowed the dairy industry to rapidly improve the genetic value of dairy cows.

This is because every farmer can now purchase a straw

of semen from the best bull.

For example, in the US, we are producing two-thirds more milk today

than we did 60 years ago, and we're doing it with about one-third of the cows.

This is because of the increased genetic value for milk production

that resulted from widespread adoption of artificial insemination.

Now, this increased milk production has greatly reduced the environmental impact

of dairying.

This rate of genetic progress would not have been possible with bull breeding.

Another reason is the cost of purchasing and

maintaining a bull, which can amount to several thousands of dollars per year.

Bulls can also carry and spread venereal disease, and

will occasionally become infertile.

Finally, bulls are unpredictable, and

every year we hear stories of people being injured or killed by bulls.

For these reasons, most dairies use artificial insemination, and

accurate heat detection is a key component to a successful AI program.

Like every challenge,

to overcome it we must break the challenge down into its essential elements.

First, we need to inseminate cows after they come into estrus, but

before they ovulate.

Research has shown that cows will ovulate about 30 hours from

the point they enter estrus.

The problem is that we rarely know exactly when a cow comes into heat.

Current recommendations for heat detection stipulate

that dairy personnel should watch cows three times a day for 30 minutes,

especially during times when cows are moving to and from the milking parlor.

Now, this recommendation is rarely adopted, because farmers are busy and

often multitask heat-checking with other duties on the farm.

Furthermore, cows in modern dairies are often housed in barns with concrete

floors that can be slippery.

This will discourage cows from mounting other cows or

allowing other cows to mount them.

In hotter climates, it is essential that cows are cooled with fans or

water sprinklers,

because hot cows will not exhibit signs of estrus, especially during the day.

Cows that have feet or leg injuries, or that are losing weight due to

the demands of lactation, will also not show signs of estrus.

If you remember, I mentioned previously that cows come into heat during

all hours of the day and night.

So how often are cows being watching during the night?

If a mature cow comes into heat at 9PM,

she might be out of heat by 6AM the next morning.

Thus her entire cycle will be missed, and her breeding will be delayed.

Finally, it is important to remember that signs of heat covered in the last lecture,

including increased activity, vocalization,

chin resting, mounting other cows and

evidence of mucus discharge are all called secondary signs of estrus.

And they can be seen before, during, and after a cow is in heat.

The defining sign that a cow is in heat is that she will stand for

several seconds when being mounted by another cow or a bull.

Ideally, this is what is used to make a decision to inseminate a cow.

>> Let's focus in on the period of heat itself and

the signs of heat that may occur prior to or during heat.

The primary and

most reliable sign is that the cow stands to be mounted by another animal.

A cow that is not in heat will quickly walk away, if an attempt is made to mount

her, or she may turn and butt the cow attempting to mount her.

A cow standing to be mounted is the only accurate sign of of estrus.

Other signs, called secondary signs, which are less reliable, but

are good clues that heat may be near, include mounting other cows.

These cows may or may not be in heat.

Mounting other cows may be a sign that they are approaching heat.

These cows should be observed closely for other behavior, like a clear

mucous discharge from the vulva and swelling and reddening of the vulva.

Persistent trailing and attempting to mount other cattle and

less time resting, bawling, and general excitement and nervousness.

Tail head hair that has rubbed off or fluffed off, and

dirty flanks, sniffing the genitalia of other cows, head raising and

lip curling, and chin resting and rubbing the backs of other cows.

>> Once the cow is detected in standing estrus,

it is important to inseminate that cow such that the sperm have time to travel

to the oviduct prior to the arrival of the ovulated egg.

Remember, fertilization takes place in the oviduct.

As a general rule, we say that sperm have a life span of about 24 hours in

the female reproductive tract.

And that the egg has a life span of about 12 hours after it is ovulated.

Remember, we know that a cow will ovulate roughly 30 hours after she enters estrus.

Yet we almost never know the precise time when the cow first entered estrus.

So the best recommendation is that cows detected in estrus

should be inseminated as soon as possible, within the next couple of hours.

If the farmer knows precisely when the cow entered estrus or

stood to be mounted, then we use what's called the AM/PM rule.

The AM/PM rule states that if a cow is first detected in estrus in the morning,

then breed her that afternoon.

And if she's first detected in heat in the afternoon,

then breed her first thing the next morning.

Once again, the AM/PM rule works well when the farm

feels confident they know when the cow first entered estrus.

If the cow is seen in heat first thing in the morning,

it is possible that that cow came into heat the night before.

In this case, our first recommendation should be followed, and

the cow should be bred as soon as possible.

To summarize, accurate estrus detection is a key component

of artificial insemination breeding.

The goal is to have viable sperm in the oviduct when the egg arrives

shortly after ovulation.

To accomplish this, we need to breed cows towards the end of estrus, a period of

time that can be as short as six to nine hours in mature, lactating dairy cows.

However, we often don't know precisely when the cow first came into heat.

Therefore, we recommend that cows detected in estrus should be bred as soon as

possible, unless it is known when the cow first came into heat.

Then we recommend that cows detected in heat in the morning are bred in

the afternoon, and

those detected in the late afternoon are bred the following morning.

This is called the AM/PM rule.

Of course, all of this relies on accurate estrus detection.

Secondary signs of estrus including increased activity, vocalization, chin

resting, and mounting other cows are good signs that the cow is close to estrus.

However, a definitive diagnosis of estrus is that the cow will stand for

several seconds when mounted by another cow or a bull.

To detect estrus accurately, farms should conduct dedicated heat detection at least

three times per day for 30 minutes each time.

Personnel tasked with estrus detection

should have this as their primary duty during this time,

and the cows should be in a comfortable, cool environment with good footing.

In the next lecture, we wrap up our module on reproduction with a discussion

of factors affecting conception rate and how to detect pregnancy.

[MUSIC]

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