[SOUND]. As we think about how do we know that some galactagogue or some galactopoietic factors impacting lactation, we're really talking about milk production. What effect does it have on milk production? Well, how do we measure that? And so just to kind of give you some ways of thinking about that here. Again, how do we determine an effect on milk production? We need to know what the milk production is. In the case of, for example, a dairy cow, where we're putting machine on the cow, we're usually measuring milk volume or milk weight, and converting one to the other, as the case may be. The key to this is that this machine is pretty much the same all the time. And we determine, as the milkers, how often the animal is milked, how often the cow is milked, two times a day, three times a day, whatever the case may be. And again, the machine is pretty much the same. It's going to be removing milk for the same amount of time, etc., etc. So there's a lot of control here over that part of kind of the equation in terms of how milk is removed. On the other hand, when we have most other animals, aside from animals that we're going to milk on machine, we're really talking about the young removing the milk. So how do we estimate milk yield? We can in the case of the litter-bearing species like rats, mice, pigs, for example, we can do litter weight gain. So the idea is that the very, very young, the only source of nutrients they're getting is from mom from the milk. And so any weight gain they have is a direct result of the milk that they were ingesting. So if they get less milk, they're going to grow less fast, if they get more milk, they're going to grow faster. And so litter weight gain or, in this case, for piglets or other species, you can do individual animals. Piglet weight gain, putting it on that basis. We can also do something called Weigh-Suckle-Weigh. So these two are very indirect because they're looking at the product of ingesting that milk and how the animal grows. Weigh-Suckle-Weigh is looking a little bit closer at what the animal actually removes. In this particular case what we do, say for pigs, is you remove them, the baby pigs for a period of time so that the mammary gland refills with milk. And the piglets are hungry. So weigh the piglets. Put the piglets on the mom, let them suckle til they're done, pull them right off and then weigh them again. And the difference between that weight of the piglets is what we call Weigh-Suckle-Weigh. That will give you an indication of the amount of milk that they've removed from the mammary glands. So not necessarily the amount of milk that's in the gland, it's the amount of milk that's actually been removed from the mammary gland. This has a number of issues with it. One of those issues is if they urinate or defecate or something in that interim period, your weight's not going to be quite as accurate. So another way that people have come up with, and just to hit this very briefly, there's a lot more detail than I'm going to give you. Deuterium oxide is heavy water, is what it amounts to. It's an isotope, it's a non-radioactive isotope. And what they'll do is they'll administers a dose of this to the piglets prior to the nursing and let it equilibrate. Take some blood samples so they know that basal level is and then allow them to suckle. And it's adding more fluid to the body, and they'll very quickly then, after that, take another sample. And again the difference, it's basically diluting out the deuterium oxide, in that case, in the blood, in the body of the animal. And so they can then back calculate and determine what amount of milk, what amount of fluid was removed from the mammary gland of the mother in that particular case. We also need then as we think about these things. Let's go to the next slide [COUGH]. To think about suckling intensity, or we can also call this milking intensity. In the case of the cow, the dairy cow, for example, if we milk her twice a day or three times a day or four times a day or whatever the case may be. Same way with the pigs, how often they're nursed here. I've got frequency of suckling, for example. Some of them nurse every 45 minutes. Some of them nurse every hour. Obviously in a 24 hour period, those that nurse at a shorter interval are going to get more nursings in during the time. That's going to impact the amount of milk that she makes. Litter size and piglet size. So, the bigger piglets are going to demand more from that mammary gland. They're going to probably remove more that the gland will turn around and respond and make more milk. And so, the bigger piglets will probably get more milk from the gland. The more piglets, in the case of a species such as this, the more piglets there are, the more glands come into production and so the more milk they're going to produce overall. Again, in the case of the cow, where we have a milking machine, the machine's always the same. It's always four quarters, it's always done exactly the same. So we don't have a difference in size as a milker. We don't have really a difference in the number of glands that are being milked at any particular time. So we need to always kind of keep this kind of things in mind. How do we determine milk production? How do we actually weigh the milk or determine how much is produced? And then also a factor that's going to come back into play, and we'll talk about this more in other videos, is the suckling intensity. Well, these are just some of the factors that are involved in that or milking intensity. So now let's review very quickly what we've talked about in these few videos here. So let's take a look at what we've gone over. Again, galactopoiesis is maintenance or enhancement of lactation. We talked about a range of galactagogues. They're substances that are used to enhance lactation, hormones, drugs, herbs and some other kinds of things. We talked about several of these these, especially some of hormones and drugs and some of the herbs. Are blood hormones or blood concentrations of the hormone limiting or sufficient? So is there enough, or if we add more, do you get more milk? Or if we decrease it, and again, getting back to is it limiting, is it sufficient? So we've talked briefly about those kinds of concepts. Numerous ways to manipulate Prolactin, especially Prolactin secretion and Prolactin response to the gland. So we can enhance Prolactin, we can depress Prolactin, and lots of different ways to do those kinds of things. We also talked about kind of the difference between cows, for example, where we have a milking machine, which is pretty constant, versus suckling the young. Young grow and so they get bigger as time goes on. So the milker changes over time where as a milking machine is pretty much constant compared to that over time. We then we also talked a little bit about the different methods of determining milk yield and the Weigh-Suckle-Weigh, again determining volume if we're using milking machines and those kinds of things. So we've hit a variety of kinds of topics to set up some of the other videos that we're going to be talking about here in this lactation module. [SOUND]
