Welcome. We're going to continue with our module on comparative lactation. And in this particular part of the module, we're going to be talking about swine lactation. And we have a special guest here today, Chantal Farmer, from Canada - from Sherbrooke, Canada. She is from the Agriculture and Agri-Food Canada - very similar to our USDA organization. And she is an expert on swine lactation and deals with swine nutrition, mammary biology in swine and so on and so forth. Dr. Farmer, welcome and we're very glad to have you here. Well, thank you, Dr. Hurley. It's a pleasure to be here. And again, she's going to be talking about milk production and mammary development in swine. We're going to be talking about, particularly, some of the kinds of experiments and research that she's done and how that kind of underscores some of the things we've talked about in other videos and other modules with regard to lactation in this particular species. So again, welcome, Dr. Farmer. Thank you. One of the really important hormones that is involved in development of the mammary gland and lactation is prolactin. And in other modules, we've really hammered home and emphasized estrogen, progesterone as an example. And now we're going to give an example of how important prolactin is for mammary development during pregnancy and especially in this species, certainly many other species as well, but in swine. So I just want to kind of remind you of some things about how the mammary gland develops in first pregnancy gilts. Up here is a day 80. And really, the parenchymal tissue is this part right here. It's not very much there at that point, and certainly the rest of that's fat pad. Not very much longer after that, day 100, so just 20 days later, it's only increased like this. It's still a lot of fat pad there. And only 10 days later, it goes from this to this really absolutely explosive growth. It's just phenomenal how fast the mammary gland is growing here. And these are all pretty much of the same scale, just to compare it with a - a cross-section of a lactating gland. Dr. Farmer's using this bromocriptine here, but I want her to tell you a little bit about the really interesting way that she applied this or administered this bromocriptine. So can you talk about that briefly? Sure. Actually, the first thing you need to know is that sows in gestation are restricted-fed, so they're hungry. So basically, what I needed to do is I put a capsule of bromocriptine in the gellum; in fact, within a ball of corn feed that was moist, I put water in it so it kind of could stick together with the little pill inside. Like a cord ball. Exactly. And then these animals were so hungry that it was so very easy. We had four days to train them before the treatment occurred, with just the ball of corn. And then they would, you know, raise up their head and open their mouth and you would just plop the ball in the mouth, and they would be happy. So it was - there was no trouble administering this bromocriptine at all. Actually, it was a treat to get this ball of corn. And they had no clue what they were eating inside the ball of corn. It worked very well. Good. A very interesting and easy way to administer this stuff. Yeah. But again, the key is it's administered orally, so it wasn't injected or anything like that. Exactly. So it could be added in the feed. Good. So this is to remind you that during lactation, I've only put in the - kind of the last what, roughly, not quite two-thirds of the pregnancy here. Again, exponential growth during lactation. And what Dr. Farmer did was to do certain treatments and she'll describe the drug and so on and so forth, during these different last parts of gestation, and then looking at how that impacted mammary development. So can you briefly explain, kind of, what - what we're doing here? Yes. First, I would like to say that, contrary to ruminants, the pig does not have the hormone placental lactogen. So pigs and rodents do not have placental lactogen. They do? I'm sorry. Pigs and rodents. Yes, I'm sorry. Yeah. Pigs and rodents do not have it. So instead of this hormone, what could have an effect for mammary development in late gestation? And the idea came to me, why not prolactin? Prolactin is important in lactation. Maybe it has also an effect in terms of mammary development. So in order to see if prolactin does have an effect on mammary development in late gestation, I've inhibited prolactin secretion. So first, we need to know that the release of prolactin - prolactin synthesis is under a negative control. It's under the negative control of dopamine. So if you give a dopamine agonist, you will inhibit the synthesis of prolactin, which is exactly what I've done here. So from days 50 to 69 of gestation, I've inhibited prolactin. With bromocriptine. The BR stands for bromocriptine, which is the - it's basically an ergot alkaloid derivative. Dopamine agonist, yeah. Again, it inhibits - specifically inhibits prolactin. Exactly. So I've done a study, the initial study, which we don't see here. I've given the bromocriptine from day 70 of gestation right up to farrowing. And I've seen an inhibition in terms of mammary development. So in this study, I wanted to try to pinpoint the period where prolactin is most important in terms of mammary development. So I've divided the period from 70 to 110 days of gestation in two, and I actually went even earlier than. So that's the 50 to 60 days - yeah. Exactly. So the first treatment for 20 days, 50 to 70; the second treatment, 70 to 89; and the third treatment, 90 to 109 days of gestation. So now we've inhibited prolactin at any one of those three periods. At three different time points. Yeah, exactly. So let's go to the next slide and see what the result was. Control here is - the numbers here don't matter as much, but this is parenchymal tissue, right? So again, carving out that part of the tissue that was actually parenchymal tissue away from the fat pad, or the extra parenchymal tissue. So basically, we slaughtered the animals at day 110. Day 110. That's it. And then when we dissected, we looked at the amount of parenchymal tissue, which as you remember, is the tissue where you will see synthesis of milk. Basically, in the control animals, in the first bar - in the white - you see the maximum amount of parenchymal tissue, because we do have prolactin present. Then, when we inhibit prolactin from days 50 to 69, there's some reduction, which is not significant, though, in terms of prolactin effect on parenchymal tissue mass. If you look, then, at days 70 to 89, again, the reduction is not significant compared to the control animals. But when you come to this last period of gestation, between days 90 to 109, that's where you do see a drastic decrease, as you see. Almost to 50 percent. Almost, yeah. Almost a 50 percent decrease. Definitely. So prolactin is essential from days 90-109 of gestation for mammary development. Which makes a lot of sense, because that's the period where you have most of the mammary development occurring, from days 90 to 110. Remember that exponential curve? Most of that's happening that last little bit of the pregnancy. Yeah. That's where prolactin is having its main effect. Good. So clearly showing an impact of prolactin on mammary development in gestation in this particular species. So in the slides we just saw a few moments ago, what Dr. Farmer was doing was inhibiting prolactin during pregnancy and showed that, especially late gestation, inhibiting prolactin has a significant effect on mammary development. So now the next question is, what about right up at the time of farrowing? So we remember - recall that there's a prepartum surge of prolactin that's really involved in pushing lactogenesis, getting that milk production, colostrum production going effectively. So what happens when you inhibit that? So let's get to the next slide, and we'll let her explain this experiment. Okay. What we see here on the horizontal axis represents time, and F is farrowing. Farrowing or parturition. Yeah. So as you mentioned earlier, right before farrowing we have a nice big peak in prolactin. So the question here was if we remove that peak of prolactin before parturition, is there any effect on lactation? So what we've done is use the same treatment as in the gestation study - so using bromocriptine to inhibit prolactin synthesis. So between days 109 and 114 of gestation, I've inhibited the prolactin synthesis, as you can see here; so we have no more prepartum peak. And then, in terms of results - if we can go to the next slide. In a normal animal with the prolactin peak, piglets will have milk from the dam. So there is no problem of lack of milk. But if you remove this prepartum peak of prolactin, the piglets will die. Which is amazing. It tells us that, now, prolactin is essential for the onset of lactation, for the lactogenesis process to even take place. Which is something that is very interesting. So now we have two examples of how prolactin is really critical, not just in pigs, but in many species and certainly in this species, very, very critical late pregnancy and then certainly this, we'll call it a peripartum period, of when prolactin is really important for initiating lactation. So now, what we were interested in is, well, what effect does prolactin have during lactation? And again, in a species like swine, it's really extremely important. And some of the work Dr. Farmer has done has really shown that very, very elegantly. So what she did was to set up an experiment where she was, again, using this bromocroptine, this prolactin inhibibitor, during lactation at different times of lactation. Let's take a look at the first slide and see what this experiment's all about. Okay. The horizontal axis here, we have the days of lactation, and the vertical axis is a mean piglet weight, as an indication of the amount of milk produced, because these piglets were not eating any creep feed. So any growth they have is because of the intake of milk that they are having. Okay. So this is actually the control animals, so that we see the normal growth of the piglets throughout lactation. Okay. Next slide. And so up here, just to remind us that we have prolactin levels in the control animals, again, during this first week. And so this bar down here represents the first week of - excuse me, bromocriptine treatment. We have prolactin levels in the bromocriptine-treated group, which is, in this case, 14 nanograms per mil. Basically, one-tenth of what we have in the control groups. So just to kind of give you an idea that, yes, the bromocriptine is working, it's bringing prolactin concentration down. Exactly, which was the goal. So basically, when we do reduce the prolactin concentration in that first week of lactation, you see that the growth rate of the piglets is almost non-existent. So they manage to maintain their growth rate - I mean their growth - their weight, sorry - but they don't grow anymore. And this is definitely due to the absence of prolactin. But there is some prolactin left, which may be the reason why they maintain their weight, but they don't grow at all. Now that's an important point, because things like bromocriptine do not bring prolactin down to zero. There's still a little bit there. This is always kind of a question of, is that doing anything in itself? And probably, it's doing enough to maintain it during this time period. Exactly. And then after that's done, these animals start to recover, although they never get back to the other animals, the control group. Exactly. So that's an important point. Yes. They don't catch up afterwards. The growth rate goes up, but they never catch up with the other group. Let's go to the next slide, which is week two. Again, bromocriptine during the second week. Okay. So I tell people, you know, I could have tried to manipulate the data and it couldn't have been any better, but there is no manipulation here. So if you see in the second week of lactation, if you give the bromocriptine, again, no growth rate of the piglets. It's amazing. This was really a novel finding, that even once the lactation process has started, once it gets into the galactopoiesis, as we call the maintenance of milk yield, even in the second week of lactation, if you don't have prolactin, lactation is inhibited. But then again, after the treatment stops, piglets start to grow again, but never, never catch up with the control animals. And they're - they're way behind at that point. That's it. Very much behind, yeah. Okay. Let's go to the next slide. So in this case it's week three, with the bromocriptine treatment. And the same finding again. Same as in week two or week one. No growth of the piglets when the bromocriptine is given. And again, growth rate goes up after, but no catching up at all. Again, we can see in our prolactin concentrations, still very high prolactin: 81 nanograms per mil versus the bromocriptine. So it's still doing its job, yeah. Okay. Next slide. Finally, the fourth week. So even in the fourth week of lactation... And we should also point out, remind people that this - you know, peak lactation is right about in here. It is right about, say, 18 to 21 days, something like that. This going even a little bit past peak lactation. Exactly. So even at that stage, if you get rid of prolactin, you have no growth rate of the piglets. So it tells us, any time during the lactation of sows, if you don't have prolactin, it will inhibit lactation. So we've seen that prolactin is extremely important for both mammary development and lactation in this species, again, as it is in many species. And during that mammary development phase, during the lactogenic phase and then in galactopoiesis, in terms of maintaining lactation, it's very, very important. So again, Dr. Farmer's done a variety of experiments here to demonstrate those kinds of things. Yeah. So this was very informative and important. So now, as an endrocrinologist, the next step, I guess, would be trying to give prolactin to these animals and see what happens. Manipulate it in some way, yes. So then that's the next step that we've been working on also in the past years. Good. Thank you. So again, we thank Dr. Farmer for visiting us and we hope you enjoyed this video.
