Environmental Pathogens

Loading...

来自 University of Illinois at Urbana-Champaign 的课程

Lactation Biology

12 个评分

University of Illinois at Urbana-Champaign

Lactation Biology

12 个评分

Lactation and especially milk, which is the product of that unique mammalian process, are routinely encountered within our daily lives. Nevertheless, they often are poorly understood by many, even including many who are engaged in the business of producing milk. The overall course goal is to introduce fundamental concepts that form the basis for understanding the biology of lactation, the biology of the mammary gland, and the products of that important physiological process. As a learner in this course, you will be provided with a series of easily understood presentations that collectively will help you build a foundation for greater understanding of lactation. You will be able to engage with other learners so that you can extend your learning beyond the video presentations. Ultimately, you will be able to construct your own mental model for understanding the wide range of topics that relate to the biology of lactation. Upon completion of the course, you will be prepared to expand your knowledge and understanding of lactation from other sources and experiences as you pursue your individual interests. Before you start the course, I suggest that you identify a question or several questions about lactation that you already have on your mind. This could be from your own experiences, something you read about or saw, or something you have wondered about. Write down your question(s) and use that to help you decide how to engage with the content of this course. You might engage with the modules in the order they are presented, or start with a module that is of particular interest to you, or pick and choose modules in any order. I encourage you to engage in all of the types of learning activities that this course has to offer, including but not limited to, the discussion forums, quizzes, peer-review assignments, and concept maps and other learning aids.

从本节课中

Module 9: Mastitis

The mammary gland is an excretory gland, meaning that it produces a fluid that is secreted to the outside of the body. These secretions leave the gland through a series of ducts that eventually open to the outside of the skin. The presence of these openings not only means that the mammary secretion can leave the gland, it also means that microorganisms can enter the gland. When that happens, the gland may become infected and present as a disease known as mastitis. Mastitis is an inflammation of the mammary gland, the inflammation most commonly being caused by an infection by a pathogen. Mastitis is the most costly disease in dairy cattle, but is also prevalent in other species, including our own. We will examine many of the aspects of how this disease is manifested using the dairy cow as our primary example in this module. We will examine mastitis at the level of an individual cow, as well as at the whole herd level. And then to fully integrate and apply the knowledge gained about this disease, we will examine several real-life cases of herd-level mastitis problems faced by dairy producers.

Mastitis Syndromes11:12

Mastitis Types7:08

Contagious Pathogens7:32

Environmental Pathogens6:03

Other Pathogens5:39

与讲师见面

Dr. Walter Hurley, PhD
Professor Emeritus
Department of Animal Sciences

[SOUND].

So that was several pathogen three major pathogens that we consider to

be contagious.

Now we want to look some environmental pathogens.

So they are in the environment.

So let's take a look at the first set.

And I called it the first set because we collectively call these coliforms.

They're environmental pathogens, they're all gram-negative and

there's three species that which are very often found in terms of bovine mastitis.

Eschericha coli, e-coli.

Klebsiella oxytoca and klebsiella pneumoniae.

Again, these are collectively called the coliform or coliform mastitis.

They have a very similar response.

And so I'm going to say they're not identical, obviously,

because they're completely different species of bacterium, but

the response of the cow is very, very similar.

So that's why we collectively think of them as coliform.

So coliform mastitis could be any of these three.

Next slide, so, Coliform Mastitis.

How do we think about this?

All of these species inhabit the gastrointestinal tract, so,

they're going to be in the manure, they're going to be in the environment.

In the manure, in the bedding, polluted water, in the soil.

So, anywhere that animal is potentially that these coliforms might be there.

In during milking so when that street canal is

open somehow those pathogens are getting in there.

In addition to that we're told that when cows are milked especially with a machine

that that street canal stays open, those sphincter muscles around the street canal.

Or stay relaxed that the thing is open for roughly an hour after the cow is milked.

So with a lot of times producers will do is, they'll feed cows right after,

cows like to eat, they'll feed cows right after being milked.

So the cow and most cows eat standing up so it gives them that time for

those sphincter muscles to close that street canal down lessening the chance

of getting some of these bacteria in the mammary gland.

So as a way to manage the cows right after milking.

It's highest, it likes hot, so it's highest in the summer,

lowest in the winter months in terms of the, kind of the pathogen load.

And the environment common in very early and late dry period in the peripartum,

so around that time when the cow's calving, and then around the time or

right after the time that she's dried off at the end of her lactation.

It's most commonly when you'll have coliform mastitis occurring.

Typically, it manifests itself as clinical mastitis, so as we think about

we have an unusual number of cases of clinical mastitis.

One of the first things we started thinking about is well,

it might be environmental and it might be caused by the coliforms.

Not a guarantee, but this is one way to kind of think and start to segregate out

different types of mastitis and what's the cause of a particular problem in a herd.

50% of them were short durations, 10 days.

They may actually cure themselves, so it is responsive to antibiotic therapy, but

that may or may not.

Again, if it's a fairly mild case of coliform mastitis,

it might actually cure or clear itself out.

So again, they're usually fairly short durations, so

we don't normally find coliforms associated with chronic mastitis,

which is over an extended period of time.

It can progress to a peracute mastitis,

and that's not at all unusual.

But certainly if we see a lot of peracute mastitis,

it could be caused by many different kind of bacteria.

But a lot of times our first thought is,

it's one of the coliforms causing the problem.

About 1% of the cows prevalence.

So it makes up to 30 to 40 % of the clinical cases.

So if 2 to 4 % of the cows during their months period have clinical mastitis then

a little less than half of those we can kind of assume will probably going to be

caused by coliform mastitis.

So that's a standard proportion that we might think of in a dairy herd.

Another set of bacteria that we associate with environmental mastitis are called

Environmental Streptococcal species or Environmental Strepts.

So Strept uberis, Strept dysgalactiae, again,

they inhabit gastrointestinal tracts, so they're going to be in the bedding.

Especially kind of organic beddings such as straw we'd typically find them there.

Common infections during the dry period so

a lot of times they will be in the mammary gland.

When you dry the cow off and of course you stop milking the cow so

any bacteria in there going to cause a problem.

Therefore dry cow antibiotic therapy is really very important for

this particular bacteria as well as other kinds of bacteria.

The prevalence increases in milk, wet milking.

What we mean there is that washing the teat off, if the teat is still wet

they could be out here, they could be on the bottom of the utter.

And then again once that street canal is open they potentially can work their way

in there.

Dirty sponges,

if you're using sponges we don't recommend that all that you use sponges anyway but

dirty towels again washing one cow's teat using a towel or a sponge or cloth.

Going to another cow you can potentially contaminate that cow's teat as well.

These are usually a bit more mild, they typically don't go to pericyte as much

as coliforms do, but certainly again, it's possible that they could.

Again, clinical cases are usually mild,

relatively speaking on average compared to again the coliform mastitis.

So again another type of environmental pathogens that we associate with

the environment again these environmental Streptococcus species.

[SOUND]

探索我们的目录

免费加入并获得个性化推荐、更新和优惠。

Coursera 致力于普及全世界最好的教育，它与全球一流大学和机构合作提供在线课程。

© 2019 Coursera Inc. 保留所有权利。

通过 App Store 下载

通过 Google Play 获取