The Neonate

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Del curso dictado por University of Illinois at Urbana-Champaign

Lactation Biology

5 calificaciones

University of Illinois at Urbana-Champaign

Lactation Biology

5 calificaciones

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.

De la lección

Module 5: Mother & Neonate

The peripartum period, the time shortly before, during, and after giving birth, is a time of rapid changes in the mammary gland, the mother, and the neonate. Extensive physiological coordination occurs between the processes leading up to and giving birth, the formation of colostrum, the initiation of lactation in the mammary gland, and the subsequent removal of milk by the neonate. In this module, we explore how the mammary gland changes around the time of giving birth when the gland transitions from a non-lactating to a lactating state. Part of this transition is the production of colostrum, the first mammary secretion produced by the gland after giving birth. Another part of the transition is the changing regulation of mammary gland function from one being driven primarily by hormones associated with pregnancy and parturition to one where milk removal, by the neonate or milking machine, is the driving force in gland function after birth. In this module, we examine some basic characteristics of the neonate, how lactation is initiated (lactogenesis), and the formation and special components of colostrum (immunoglobulins) and their impact on the neonate.

Peripartum Period10:07

A Cow Calving3:49

The Neonate8:18

Conoce a los instructores

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

[SOUND] So now you've

seen a calf being born.

And going from this stage, coming out, and

then what happened right immediately after that.

So let's take a little closer look at what's going on here.

So take a closer look at the neonate.

The mammalian fetus resides in the very nice, warm, and cushy, and moist,

and protected environment just prior to start of being born up here,

when it was a fetus, before it started going through the birth canal.

And all its requirements are being provided by the mother because it's inside

the mother.

But, going to the next slide, at birth,

so this little guy down here is now all of a sudden in a very cold environment,

a very dry environment compared to what it was when it was in the uterus.

Unprotected environment, but

it's still very much dependent upon mother for everything it needs.

Except it can breathe now, it doesn't need oxygen.

Whereas up here, it was getting oxygen from the mother's blood.

Now it's getting oxygen because it can breathe.

Otherwise, it needs water, it needs nutrients, and protection, and

other kinds of things.

Let's go to the next slide.

This is actually an image of a newborn piglet who is just getting

its first drink of colostrum.

What does this guy have or does not have?

Very limited fat stores, body adipose.

Mammals are born pretty scrawny,

they can put on body adipose very quickly for insulation.

As well as metabolizing that body adipose or body fat.

But very limited fat stores, and

again, they need to be kind of scrawny to get through the birth canal.

Available body fat is not easily metabolized.

So the fat that is there is usually not easily metabolized.

Limited glycogen stores.

So glycogen, particularly in the liver, is used up very, very quickly.

Within a number of hours, frankly, after being born.

And so it just doesn't have a lot of energy stores there.

So it needs milk and colostrum from mother very, very quickly for that energy.

Poor gluconeogenic capacity.

So gluconeogenesis is the synthesis of glucose in the body of the animal.

So neogenesis, meaning new generation or new synthesis, of glucose.

Which obviously is needed for energy for the animal.

The capacity to do that and

deliver the neonate is not very great at the time it's born.

It will develop over the next number of days to weeks.

Low iron stores, again, for making blood cells, and hemoglobin, and so on.

Many species are what's called agammaglobulinemic.

Agammaglobulinemic, A, meaning without.

Gammaglobulins are the immunoglobulins, are the antibodies.

Agammaglobulinemic, meaning there's just not very much there in the blood.

So very low blood levels of immunoglobulin concentrations.

This is very much species-dependent.

And so for example, a species like this,

or cows, or goat, sheep, and those kinds of things.

They're born with very, very low immunoglobulin levels.

Requires that to come from the colostrum.

And we'll get into that in another video or two here,

a few videos in the mother/neonate module.

In our species, on the other hand, we're actually born with immunoglobulins.

Because the primary immunoglobulins, the IgGs,

were transferred to us when we were still a fetus.

So again, a lot of species variation in terms of what this colostrum,

antibody, immunoglobulin story is all about.

And again, we'll cover that in another video.

Next slide, what do they have or not have?

Again, structurally immature intestines.

So even though, if they start ingesting things,

they're not really that efficient at taking full value of the nutrients and

the other things that are in whatever they are ingesting.

Low activities of pancreatic enzymes.

Stomach pepsin, again, a major protease in the stomach.

Low activities of many intestinal enzymes at birth.

Again, they're going to increase then, after birth, in the next few days.

Stomach acid generating capacity.

So in adults, what we do we have for adults?

Adults are going to have a pH of about, say, roughly 2.

Make sure I write this in the right place, oops, a little bit too high there.

It's about 2, pH of 2, whereas in the neonate,

it's more like about 3.5.

So still pretty acidic, but not nearly as acidic it would be, for example,

in ourselves as adults.

So again, that acid generating system is just new.

It's just not really going full blast at that time that they're born.

What they do have, on the other hand, is they have fairly high renin-like activity.

So renin, in particular,

is a proteolytic enzyme in the stomach of the calf, for the bovine.

And it very specifically digests the kappa casein,

allowing that curd to form in the stomach.

And allowing gradually for

digesting of the casein, the major protein in milk in that particular species.

Increasing lactase activities, so lactose is a major sugar in milk.

Again, galactose and glucose, lactase would break those apart.

And they could then be individually metabolized in the animal.

Low at birth, but

increasing fairly rapidly after that in the intestine of the neonate.

And increasing salivary lipase.

So saliva, lipase, lipid-digesting enzymes from the salivary glands,

again, are increasing at that particular point.

So after a while, hours to a few days, this starts to change so

that the neonate is able to really take full advantage of the colostrum

in the milk that it's ingesting at that point.

So what we've done in this particular video is just kind of very,

very briefly talk about this individual here.

So much of this course we're talking about the mammary gland of the mother.

And synthesis of milk, and those kinds of things, mammary gland development.

We just very briefly went over what this animal is when it's born and

how quickly it changes.

So let's do a quick review now.

Again, this idea that the neonate goes very rapidly from this very,

very protected, warm, moist environment in utero.

Comes out, and it's cold, it's unprotected, it's dry.

And so that's a very rapid change for the neonate.

Neonate nevertheless remains very dependent upon the mother.

It can't simply get up and, let's say the new born calf can't get up right away, and

go down to the stream, and drink water.

It's reliant upon mother for pretty much everything,

except for the fact that it can breathe and get oxygen.

Has special needs because it has very limited metabolic capacity.

For example, limited gluconeogenesis capacity, just one example.

Immature intestinal development.

So the intestine is just not quite developed yet

to the point of where it can maximize its digestion of nutrients coming in.

Limited enzymatic capacity for digestion.

Again, a lot of those enzymes are at low levels, but

increasing fairly rapidly after birth.

Limited immune protection, so depending upon the species.

And many species, they are born without immunoglobulins in their blood.

And they have to get that from the colostrum.

And some other species, such as our own species,

we are born with those immunoglobulins already in our blood.

And changes to mammary function are occurring simultaneously.

So part of the reason I wanted to introduce you to the neonate is in

those rapid changes occurring in that particular animal is in the mammary gland.

What we're going to find when we go into some of the other videos is

that there are very rapid changes,

shifting over from colostrum composition to mature milk composition.

And other things going on in the mammary gland during that early period of

lactation around lactogenesis and then immediately after lactogenesis.

[SOUND]

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