Joining together for another Journal Club to discuss vitamin D as a lactation influence on dairy cows are dairy leaders and nutritional experts Dr. Bill Weiss and Dr. Corwin Nelson.
Guests: Dr. Bill Weiss, The Ohio State University and Dr. Corwin Nelson, University of Florida
Joining together for another Journal Club to discuss vitamin D as a lactation influence on dairy cows are dairy leaders and nutritional experts Dr. Bill Weiss and Dr. Corwin Nelson.
Dr. Weiss, professor emeritus at The Ohio State University spent nearly 33 years of his career focused on dairy cattle nutrition and has published more than 140 journal articles. He began the conversation, introducing the article “Effect of prepartum source and amount of vitamin D supplementation on lactation performance of dairy cows” and mentioning Mike Piondexter as the first publishing author. 2:20
Discussing the research study in depth was Dr. Corwin Nelson, Piondexter’s advisor. He began by introducing the Journal of Dairy Science article, highlighting the nutritional effects of supplementing vitamin D and the connection between feeding two different forms. 6:15
Dr. Nelson shared studies dating back to 1980 to indicate some vitamin D degradation. But added that most rations have between 30,000 to 50,000 units of vitamin D3 on top of basic international units. 9:40
In the article, the abstract shows productive measures such as body weight and condition, dry matter intake and factors. However, Dr. Weiss mentioned the majority of research data derived from cows during their last few weeks of weaning. 13:21
Dr. Nelson said that research also analyzed net energy between using colostrum and vitamin D, adding that feeding the 25-hydroxyvitamin D in the ration resulted in higher results of energy. 14:14
When looking at energy corrected milk, Dr. Nelson said in about 42 days he’s seen interaction between cows producing the most milk and the three milligrams per day of 25-hydroxyvitamin D supplementation. 19:01
Anti-inflammatory is another mode of action vitamin D has shown to effectively decrease in cows with lower serum. In fact, three to four weeks is the optimum benefit when it comes to supplementing less than the elevated 25-hydroxyvitamin D recommendation. 32:55
It was also mentioned that there may be a possible United States Department of Agriculture (USDA) grant opportunity to look at the long term effects of cow responses, maternal and neonatal vitamin D nutrition and a more focused approach to the immune system are all upcoming research modes of actions. 42:27
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Scott (00:08):
Good evening everyone, and welcome to the Real Science Exchange, the pubcast where leading scientists and industry professionals meet over a few drinks to discuss latest ideas and trends in animal nutrition. I'm here in Fort Wayne, Indiana with Dr. Clay Zimmerman, my co-host today, and we are at the 2023 Tri-State Nutrition Conference. Clay, welcome.
Clay (00:30):
Good to be here, Scott. Thanks.
Scott (00:31):
Yeah. We're also here with Dr. Bill Weiss, our in-house professor for my favorite genre of the Real Science Exchange, which is the Journal Club. So, bill, welcome. Welcome. Bill. Why don't you start off by giving us an overview of the paper that you've selected for us today, and then introduce your guest.
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Bill (01:47):
Thanks, Scott. This paper is published earlier in JDS Journal Dairy Science. The title is Effective Pre Partum Source and Amount of Vitamin D supplementation on lactation performance of dairy cows. And I picked this one. I've done some work in vitamin D, so it's of interest to me, and it's also kind of new. The type of vitamin D we're gonna talk about is still very new in the dairy industry. The first author was Mike Poindexter, who was a graduate student, and the guest here is his advisor. I take it. I can't remember. And that's Corwin Nelson from University of Florida. So, welcome Corwin.
Corwin (02:28):
Yes. Welcome. It's good to be here in Fort Wayne.
Bill (02:31):
And first, if you just a little bit, I like when it's a grad student's paper, if you'd give us just a little background on the student, where he came from and where is he now, and a little bit, give him some credit, I guess.
Corwin (02:43):
Yeah, definitely. Definitely. Yeah. Michael Poindexter, he did his master's in PhD at University of Florida in our animal molecular and cellular biology program there. He did his bachelor's at University of Arizona. Started out doing some work with Bob Collier there, and that's how he got kinda introduced in dairy nutrition and got started there. He has a really interesting background. He is born in Norway and spent a lot of time overseas and then, you know, because of his family and then eventually in Arizona and then Florida. Now he's at in Colorado working as a herd manager there.
Bill (03:23):
I can see Norway and Arizona and Florida. I can see why he went to the south. So,
Corwin (03:53):
All right. I'll try to keep this as simple as possible. And, a clear overview. So vitamin D, which it's, it's a common term is just vitamin D, but that really refers to a number of different metabolites. Vitamin D3 that we normally see in our dairy cow diets. That's the, form that's just produced, our skin exposed to sun. The cows produce at no problem exposed to sun. Typically cows are indoors, so we just supplement vitamin D3 in the feed, but that's not the active form. That vitamin D3 is metabolized to another form called 25-hydroxyvitamin D3 are also known as Calcifediol. But that's still not the active form. It undergoes one more step of activation, which is really tightly regulated and that's to the 1,25 Dihydroxy D3, or also known as Calcitriol.
Bill (04:48):
And you know, we've supplemented D3 forever almost. And the that's we're gonna talk about today is the 25 hydroxy D, which that's the term I use, I'm used to, so that's the term I'm gonna use. So then with that, so we're looking at the next step in metabolism. So what was your hypothesis? Why'd we do this? Why'd you do this experiment?
Corwin (05:11):
Yeah, so we, as we mentioned, D3 is the one that we normally feed. So why feed this 25 hydroxy D when, you know, the body already produces that, you know, what's the advantage? So the hypothesis there, it goes back to some data and previous experiments where we found that the 25 hydroxy D is actually more effective at increasing serum concentrations of the 25 hydroxy D. So that it's that availability of that 25 hydroxy D3 to the, the cells of the body is really the driving hypothesis behind us of our theory behind this of what's taking place. Why would this be of benefit? So what we found in previous experiments that feeding this 25 hydroxy D was much more effective than just feeding the traditional vitamin D3.
Bill (06:05):
So then again, just based on the, what was the overview of the treatment? The experiment, what were the treatments and the cows that were used?
Corwin (06:15):
Yes, yes. So we, we fed two different forms of vitamin D3 that are vitamin D, the vitamin D3, which we called Calciferols, that's another name for it. And the 25-hydroxyvitamin D3, which we, we call Calcifediol just to, so we're, we'll use 25 hydroxy D here today, but the terms are interchangeable. And so we fed those two forms as either one milligram per day, which is equivalent to 40,000 units of vitamin D3 or three milligrams per day, which would've been, you know, 120,000 units of vitamin D3 per day. So, clarify here we use the milligrams rather than international units because that international unit is specific to vitamin D3. So we use the milligrams just for to be more specific on the amounts.
Bill (07:07):
Yeah, I think that's important. If we start doing the 25 hydroxy, the IU system has to be abandoned, cuz we don't know what the, the equivalency of 25 D to D is. So
Corwin (07:19):
Yes. Yes. Mm-Hmm.
Scott (07:20):
Corwin (07:31):
There was some work done back in I think 1980s. Ron Hurst had done some, and Tim Reinhardt done some of that work. There is some degradation that takes place there. I I don't know the exact numbers. Maybe Bill remembers some of that work.
Bill (07:48):
Vitamin A is very degradable. It's much less degradable than A. So, I can't give you a number, but it's relatively stable for a vitamin.
Scott (07:56):
Okay. And both sources, we know that?
Bill (07:59):
We don't know anything about 25, the stability in the room at a 25. Right. I nothing about that.
Scott (08:04):
Yeah. Well then the other question I had is, where do cows traditionally get their vitamin D? Right? There's not a lot of exposed skin. So is it all dietary?
Corwin (08:12):
No, actually they naturally do get it from sun exposure. There's some interesting work done back in Denmark 10 years ago or so looking at, you know amount of time in the sun, amount of skin exposed to the sun. And, it is really kinda solidified, the cows are able to produce vitamin D3 when they're outside in the sun during the summer. Yeah. Pretty efficiently.
Scott (08:38):
Huh, Interesting.
Clay (08:40):
So, Corwin, was there basal level of vitamin D in the diet?
Corwin (08:44):
Yes. Yes. I, so I should have clarified that part. The treatments that we added there were on top of 20,000 units of vitamin D3 in the diet. So typical rations are gonna have somewhere between 30,000 to 50,000 units of vitamin D3. We were targeting close to what at the time would've been the NRC recommendation for D3 and close up diets. And that was 20,000 units per day
Bill (09:11):
In addition to basal or,
Corwin (09:14):
Yeah, so the basil was 20,000 units at international units of vitamin D3 per day. And then we added those treatments on top of that. Okay.
Bill (09:23):
So, you're actually about two x NRC on D3 then for
Corwin (09:27):
Yes
Bill (09:28):
Brief heartum cal. Yep. And then what, why'd you pick these amounts? They said I, under the D3 is kind of industry standard. It's 40,000. Not uncommon, but
Corwin (09:40):
Yeah, so the amounts that we were going with here, so we're, it's one of the critiques of, our own paper limitations are things that we know going into it. We're a bit on the high end here as far as the total amount of D3 and just the group that got one milligram of vitamin D3. So in total they're right around 50 to 60,000 units of D3. So that's on the high end that would be there. But that was kind of the, we targeted that amount cuz that's typically, it's at least within the range of what's typically going to be fed. And then the three milligram, we picked that because earlier work that had been done a couple different ones. One was at the University of Florida where we fed either three milligrams of the vitamin D3 or the 25 D3. That was a series of papers that we published in 2018. Martinez and Rodney were the authors on there. So that's where we picked the three milligrams from using that. And the one milligram was, we picked that of, that's a little closer to what we figured, hey, this would be at maybe a more moderate level. Let's see if we get a response out of that.
Bill (10:59):
And then just for the listeners, this was fed about three or four weeks pre partum and then after calving, they were all switched to regular D3 though?
Corwin (11:08):
Yes, that's
Bill (11:09):
True. The treatment ended at calving.
Corwin (11:11):
Yep. So we fed these there's four treatments again two by two factorial arrangement of two levels of vitamin D. So either one or three milligrams of the two different sources, either the vitamin D3 or the 25 D fed for three, four weeks, actually 24 days on average pre partum. And then after calving, they all went on the same lactating ration of half a milligram per day of vitamin D3.
Bill (11:43):
And then we'll get into the results. And let's start with pre partum. Did you, what did you find pre partum, any effects pre partum?
Corwin (11:54):
Yeah, so the, in this paper, what we focus on here is the, you know, just productive measures. Yeah. So body weight, body condition score, dry matter intake. And so we didn't see any differences in body condition score, body weight. We did see a tendency for decreased dry matter intake for the cows that were fed three milligrams of either source. And we did see that drop in dry matter intake.
Scott (12:32):
And what do you attribute that to?
Corwin (12:34):
That's a very good question. There's some, a lot of data from feedlot animals where they fed very high amounts of vitamin D3 looking at meat tenderness, meat quality. So that's kind of our best data to look at, you know, feed intake data production responses relative to feeding vitamin D3 levels of that. So they do see, in those feedlot experiments, they do see and now it's getting up to even more vitamin D like 500,000 units per day, a million units per day where they see it start to see drops in dry matter intakes. We weren't approaching that much, but there is some data out there to suggest you start to get into those elevated levels of D3, or in this case 25 hydroxy D that you will start to suppress intakes.
Bill (13:25):
It was really in the cows, not so much heifers, and it was really only the, about the last two weeks where they started separating. So it, so there may be some accumulative effect. And did you do the doses so that you know, they were three milligrams or was it a mix so that they ate more feed? They would've gotten more than three milligrams?
Corwin (13:48):
Yeah, we, we fed this as a top dress, so it was three milligrams. Okay. In some other experiments it's been mixed in, so it'd be relative to the amount that the cows are consuming. But in this one it was three milligrams. Okay.
Bill (14:00):
And then you found some stuff on colostrum effects on colostrum, which I think is a critical measure on all these pre fresh experiments we do now. So what, what did you find rel relative to colostrum?
Corwin (14:14):
Yeah, so with colostrum, we observe a tendency for increased colostrum production by feeding, and it was an effective source. So regardless of the amount of the effective source, where we had a tendency for an increase in the amount of colostrum, but it wasn't just the amount. You look at all the components that go. So in the end when you look at the, the net energy of that colostrum, we saw an effect of 25 hydroxy D there where the cows fed the 25 hydroxy D pre partum produced more the net energy of colostrum.
Scott (14:51):
And how much colostrum extra did they produce?
Corwin (14:54):
Oh, gotta look back at my numbers for that one. I think it was almost a kilo. Yeah, it was close to that. So when you look at yield, it was right around at kilo on average. It, it would've more for the net energy they were right about two megas more for the net energy. Okay. One and a half to two megas more for the, the net energy.
Scott (15:19):
And then did you take a look at the quality as well?
Corwin (15:22):
So we did measure IgG in that colostrum as well. No differences there. Okay. So the, this is consistent with the previous experiment we had done at University of Florida a few years earlier. The one I mentioned with Martinez and, and Rodney. And that work, they saw a similar increase in colostrum and that one they did see an increase in, IgG outputs, total IgG.
Bill (15:46):
What, what do you suspect mode of action here is for? That's a lot of energy. I mean, that's a lot of energy, a lot of a big increase in milk energy or colostrum energy.
Corwin (15:58):
Yep. That, that's I wish I had a, a good answer to that one. That my, I guess kind of working hypothesis right now, and I, only have somewhat limited data to really kind of push a base on, and, you know, I think it is going to the mammary gland and what's taking place in, in mammary development during that time. We do know that vitamin D is active in the mammary gland. The, the mammary epithelial cells do have the vitamin D receptors. They have the capacity to synthesize the active form, whether or not that's actually part of this process or not. I'm not certain on that. But we know they have the capacity. We know that the vitamin D receptors are present there in the, the mammary epithelial cells. So that's one possibility that vitamin D is acting.
Corwin (16:47):
There's vitamin D signaling taking place promoting that mammary development. And so I, I suggest this because we, we don't see an increase in, in serum calcium prior to during the pre partum. There is more serum phosphorus, there's some changes there. I'm not sure that necessarily would be, there's other energy factors that would explain what's going on and to cause that increase in colostrum. But the potential for activity there, vitamin D activity in the gland, there's one explanation there that we just need to dig into that one further.
Bill (17:25):
It's not intake. So it's either partitioning or greater efficiency, you know, I don't know what it is either. Correct. But,
Corwin (17:31):
Right. And this is, you know, so we can get to the postpartum part. We can talk about, you know, the effects of disease and everything. So this would be prior to disease, you know, maybe there's some other inflammatory conditions going on your late gestation that maybe that's contributed to some of it. But we don't have anything to really suggest that that's the case here for colostrum.
Bill (17:53):
We'll just move right into postpartum performance then. So what did you find relative to production post?
Corwin (18:01):
Yeah, so for milk yield,
Bill (18:03):
And I guess this was for like 40 days, you measured it postpartum
Corwin (18:06):
Yeah. 42 days. Okay. Yep. That we, we have the milk yield data. Of course, we, I guess we could have, should have, you know, dug into our records and, and pulled it out for even longer to really look at those responses. But one thing is, this is one limitation of the experiment. We didn't have dry matter intakes postpartum just with what was available for our research facilities at the time. We weren't able to keep the animals in those individual feeding gates to be able to collect postpartum dry matter, which you looking back on it, oh, I wish we would've had that. It really would've been beneficial. But, so we don't have that. We don't know what takes place is for dry matter intake. But when we look at the production response, so for milk yield, we see an interaction between the, the source and the amount of vitamin D where the cows producing the most milk, where the cows that are fed the three milligrams per day of the 25 hydroxy D
Bill (19:05):
And the the components went up as well. It wasn't just milk.
Corwin (19:09):
Right. Right. So when we look at energy corrected milk and there we actually see it in effect of the source, the cows that were producing are cows fed the 25 hydroxy D pre partum. They tended to have the greatest energy corrected milk.
Bill (19:26):
And I did, did the same calculations you did for colostrum, which is net energy, which I think's a lot better than energy corrected milk, but that's my bias. But it's like two or three mega cals. More energy on average between co I, I just average the, the, the source effects. So again, that's a lot of energy mm-hmm.
Corwin (19:56):
Right, right. It is. And it's so, and we saw similar results again in this, this previous experiment we did. And, there it was very similar in the amounts that of milk production. So I think in the previous experiment Martinez did in 2018, it was four kilos more per day of milk similar for energy corrected milk. There. They, that experiment had dry matter intake we're able to calculate energy balance and all that. So it wasn't coming from an increase in dry matter intake. So, very good question of where's that energy coming from?
Clay (20:35):
So, what's your hypothesis on the interaction with milk?
Corwin (20:41):
So the it was a, initially it's very difficult to explain as I've dug into this more, I think I'm starting to understand it more. And some of it's actually now the paper's published and I've been looking at this data more and more to, to understand it. One of the things that was I think quite helpful is one of the reviewers on this manuscript said, why don't you look at the relationship of serum 25 hydroxy D to milk production? You know, is there a relationship there? I'm glad that a reviewer asked that question because it forced me to look into that aspect a bit more. Is there a relationship there with serum 25 hydroxy D and milk production? Cuz that started to answer some more questions there. What's taking place? What may be driving that?
Corwin (21:33):
And that started to, I think as we, we’ve dug into that starts to explain that interaction a bit more there. Cause we didn't have really large increases. Our are, I shouldn't, large isn't a good word to use there, but the, the increase in serum 25 hydroxy D from feeding the one milligram of the 25 hydroxy D it was there, but it wasn't a really strong increase like we get from feeding the three milligrams. So it, when you start to look at that, that relationship between serum 25 D, which that 25 D and serum, that's what's available for the animal to use, that starts to explain what may be causing that difference in, or the interaction that we actually observed in, in milk yield.
Bill (22:16):
Yeah. I think it's another, I think really important thing in this paper is how bad the three milligrams of D# was. And you know, this, there's a re you know, there's a reason these requirements are out there. So too much is clearly too much.
Corwin (22:32):
Correct, and so I think some of that, the interaction there is driven somewhat by the, the cows fed the three milligrams of the, the vitamin D3 that co calciferol they produced the less the the least amount. And that may be why we saw this in that previous experiment, the difference in yield was because the, we're comparing three milligrams of vitamin D3 to three milligrams of 25 hydroxy D in that previous experiment. So the difference really may be driven by that feeding that three milligrams of vitamin D3 is, you know, driving down intakes, it's driving down production. There's other things there that may be going on in metabolism that we don't fully understand yet. But it is something that certainly we gotta be very cautious of. Don't just overfeed cow's vitamin D3, a little bit's good. Let's go even more. It, it's, you could say that for vitamin A as well and, and E
Bill (23:29):
Too. So,
Corwin (23:30):
Well,
Clay (23:31):
Well on the, those high doses of, of the regular D3, they weren't increasing the the serum levels of
Corwin (23:39):
Correct. So you and that's what we I think we re refer to it in this paper, but the, the data is published more in full and the, the companion to this paper in, in POINTDEXTER 2023. And yeah, there we show that serum 25 hydroxy D does not change between the cows that are fed either one or three milligrams of the vitamin D3.
Bill (24:03):
So, you know, you'd think because 25 hydroxy is more potent based on blood measures that it would be, I'm gonna use the word more toxic than D3. So why do you think D3 at these very high levels was so bad? What again, I have no idea what the mode of action is. That's why I'm asking.
Corwin (24:24):
So, right. Yeah, it's, I've been mulling this one over quite a bit too of what may be driving that because it's, to get to that final response, it's, you know, through that 25 hydroxy D and, but what we may not understand fully is what are some of those other activities of vitamin D3. there is, we do see it increase in serum vitamin D3 concentrations. And so that's definitely much more than we'd see in a typical cow. So they're going for vitamin D3, which we typically don't measure. We just did in this experiment because to explain the data, and so it goes from, typically it's like five nanograms per mil. Like if you go out and measure cows out in any area, it's maybe three to five nanograms per mil.
Corwin (25:12):
And these cows fed to three milligrams, it's up to 12 to 15 nanograms per mil. So much greater concentrations still much, much less than the the 25 hydroxy D in serum. But there's a buildup of that vitamin D3 that may be taking place in adipose tissue taking place in those hepatocytes that may be affecting metabolism ways that we don't necessarily understand completely. David Frazier writes a very interesting a review article on vitamin D toxicity and talking more about cellular toxicity rather than the classical, you know, clinical toxicity that we talk about in cows. And it's quite thought provoking as far as understanding these, you know, what should we be feeding animals as far as the source of vitamin D3. Even, you know, for people taking vitamin D supplements, he, his argument is our natural mode of synthesis through the sunlight. There's regulatory mechanisms in place to keep there from over accumulation of vitamin D3. When we're taking this by dietary means, we're bypassing that. So I mean, the same thing would be in the case of 25 hydroxy D and we gotta be careful there again, not to over supplement that because there's risk with that too.
Scott (26:31):
So if we had pasture fed cattle, there'd be more risk of over feeding of the vitamin D3, do you think?
Corwin (26:38):
No, actually, because if by the, their, the body won't synthesize more vitamin D. So if you're supplementing vitamin D3 and you put those animals out in pasture, they're not gonna synthesize more vitamin D3 when exposed to sun. All right.
Bill (26:54):
What then on recommendations one is you stick with D three, I'm gonna stick with naso. What about 25 D? What, what kind of recommendation do you think people should think about?
Corwin (27:10):
So the, when we've seen these production responses, it's been with feeding three milligrams per day. Now there's not much data in between there to say, okay, it is two milligrams sufficient is th this with one milligram, we see an increase in serum 25. At rcd, we don't see the production response. But again, I don't think we have the, if there is a, a change there, we don't have the power in this particular experiment to see what may be taking place. So one of the things that we get into it a little bit in this paper, but I, I've dug into this a bit more now after it's actually been published, but looking at interaction with disease, and I had a a talk that I was given somewhere, I don't remember exactly the venue, but somebody said, well, do we get this increase in production?
Corwin (28:02):
Is only that only occurring in the cows that are sick? Or is it also occurring that the healthy cows? So we, included in this paper, we looked at that interaction with morbidity, which there's, you gotta be careful on doing that because the, the treatments were applied, you know, prior to the disease taking place. You gotta understand that, and take that data with knowing that the treatments are already applied. So but we looked at that interaction and there's some, there wasn't an interaction with disease there. When we looked at, you know, morbidity, which would be rps, metritis, mastitis das within the first 42 days of milk, we didn't see it. There's some tendencies that we saw there, but not a strong interaction. But what I've done more recently, and this isn't in the paper, this is a, this is a just, I guess disclosure of more things that I've seen from this data than I dug into. I looked at specifically interaction with metritis, now I'm wishing I would've done this previously to include this paper. It becomes much more prominent. There is an interaction with the treatments, with the incidents of metritis. So in what we see there, it's the cows that had metritis that really benefited from from the, the, the treatment. And particularly that three milligram treatment because there's a very strong interaction with serum 25 hydroxy D and the incidents of metritis.
Clay (29:36):
So the incidents, it had an impact on the incidence of metritis?
Corwin (29:40):
It didn't have an in impact on the incidence of metritis, but it looks like it had an impact on the impact of metritis
Clay (29:48):
Okay. Yeah.
Corwin (29:50):
So I, it's I'm actually gonna present this as part of my talk here at Tri-State Dairy Nutrition Conference. I'll have that, I'll show that data in there. But it's there is a strong interaction there with the incidents of metritis with the, the MULTIPAROUS cows. I had to look at those separately. But it, what I think is taking place now is I look at this and what explains it in interaction, and it goes into one of the other modes of action of vitamin D3. And that's to I'd say contain inflammation. Not prevent inflammation, but help contain inflammation. It's one of the kind of widely known aspects of vitamin D in the immune system is acting as an anti-inflammatory. That term is very broad, but and we could go into plenty of data that talks about the anti-inflammatory mode of action. But as I look at that more and look at that interaction, I think what's happening is helping contain that inflammation, helping those cows that do have metritis get through that get through that disease more effectively than cows that had lower serum 25 D
Bill (31:03):
I forgot, I should have brought this up earlier. I'm just looking at my notes. On when, you applied the treatments pre partum, you had negative one 20 DCA or something close to minus one 20. Mm-Hmm.
Corwin (31:25):
So what we found in the previous experiment, and going back to that one again, and that was Rodney 2018, and in that one they looked at the interaction of of DECA and, and source of vitamin D. And they, they still saw a production response regardless of the level of deca. But where it really comes into play is when you look at the postpartum calcium, that postpartum calcium, particularly on day zero on day one, that is really driven by the de ad. So where I'd say that the production responses that we see are dependent on de ad, I'd say yes, because it, it comes into play when you look at that postpartum calcium. So if we're not feeding that low decca or negative Decca, those cal, that that day zero, day one calcium, it's gonna low, you're going to be at much greater risk for milk fever, which we know that's gonna cause problems.
Bill (32:25):
But there, if you don't get hypocalcemia the, the high, the 25 hydroxy D even with a, a neutral dca, you still expect a production response. Yes, yes. But with, in the real world, because you probably get more hypocalcemia without it, you, you might not
Corwin (32:42):
See that. Yep. You'd, you'd definitely running at a risk of more milk fever and that that's gonna just lead to a lot more problems.
Clay (32:49):
What, what's the feeding window for the 20 of five hydroxy vitamin D?
Corwin (32:55):
So in these experiments, we've looked at feeding roughly three to four weeks pre partum. And when you look at blood levels of 25 ATAR cd, that actually is a good window because it takes about three to four weeks of feeding this for the, the blood levels to kinda reach their kind of peak level of what they'd be at. So in other experiments, we've fed this for, let's say in lactating cows. We fed for, actually over in a group of cows, we fed over eight weeks. They get to about four weeks, and they, their, serum 25 hydroxy D concentrations will plateau at about that point. So three to four weeks seems like that's gonna be about your maximum benefit that you'll get from it.
Clay (33:40):
How long postpartum do they maintain higher serum levels of 25 hydroxy vitamin D?
Corwin (33:47):
It, it gradually decreases and it doesn't drop off rapidly it 25 hydroxy D in general is thought to have about at a halflife of about two weeks. Okay. In blood I'd have to double check our calculations if it holds up about the same. But like in this paper in this experiment 36 days out, we still had elevated serum 25 hydroxy D and the cows that were fed the, the 25 hydroxy D.
Bill (34:17):
So that brings up a question as, what about feeding this to lactating cows should you know, add fresh, fresh cows?
Corwin (34:25):
Yeah. And, and that's, and I
Bill (34:27):
Know you didn't do it in this study, but Right.
Corwin (34:29):
Well, so we did a different experiment Pointdexter 2021. We did that with lactating cows in there. It was designed to look at the severity of mastitis and dairy cows. So we did see it and we used an experimental challenge in that case. So there's, again, you gotta look at the data and the concept of an experimental challenge. But in that one, we did see it decrease in mastitis severity from that. Now, from a practical you know, return on your investment that you're getting there, probably not gonna be very effective or you're not gonna get a return from feeding this in later lactation. Right. But potentially there would be some benefit and early lactation if feeding it to those fresh cows. Again, we don't have the data from that yet to say, okay, is it really gonna be beneficial? Are we gonna see a production response from that? So we don't know the answer on that. I think it's the, that question is being worked on. There's experiments going on to hopefully have an answer to that one. But at this point, I'd say if, if you were gonna feed it postpartum during lactation, just during that fresh period would be the only time that you'd like to see a benefit,
Clay (35:47):
What did you, do you see any impacts on reproduction in these cows?
Corwin (35:52):
Yeah, we looked at reproductive responses. Really nothing there to say it's gonna be beneficial. The other experiment the, the 2018 papers they looked at, there's some benefits from the, the Cal style, but, you know, that experiment was 80 cows. So anytime you're looking, and same thing with health response, health and reproduction responses. When we have these experiments of 80, 120 cows, anything in there, it's, you gotta be very cautious and, and taking a whole lot from that data. So it's really gonna be a compilation of, of these experiments over time to be able to pull this all together and amend analyses to say, okay, is there a, is there a health response? Is there a reproduction response?
Bill (36:43):
Well, and you know, how about more than three milligrams
Corwin (36:52):
So I think that the only other work that I, I'm aware of, there might be some others that have fed more than that. I think actually your paper from 2015, bill of feeding six milligrams per day, it was
Bill (37:04):
Bad. So yeah,
Corwin (37:05):
Bill (37:55):
I think the three is a good, good max. I really do. So three milligrams is a good place to stop.
Corwin (38:01):
Yes. Yes. I think currently, I think that's a suitable amount. Serum 25 hydroxy D, they get up to about 200 nanograms per mil, which is much more than what we see in our typical cows that we go out and sample, which would be around 40 to a hundred nanograms per mil. Classically that 200 nanograms per mil is been thought of as being indicative of toxicity. But again, that's a, an association of, of toxicity, toxicity with the serum 25 D. So we, there's some limitations in interpreting that toxicity level for vitamin D, but what we've seen for feeding, at least in this short term pre partum, that there doesn't, we haven't seen any things that would be strikingly negative as far as the potential toxicity effects of vitamin D at feeding three milligrams of the 25 hydroxy D per day.
Bill (39:00):
My last question here in this, I do get questions about in the field measuring vitamin D status and 25 hydroxy in blood. Is that valid in as a field application as to decide yeah, they need more D or not?
Corwin (39:19):
Yeah, it's a, serum, 25 hydroxy is a very good marker of vitamin D status. There, there's still a lot of questions out there, even in, in human field, which more and more you're seeing this measured in practice all the time. And there's questions about how should we take this data and use it. And I'd say that we'd still kind of be at that point in dairy nutrition because we don't necessarily have the data to say, okay, this level of serum 25 hydroxy D this concentration is what corresponds to improved health, improved performance. We don't quite have that level to say, here's what it is. Now on the very low end, we could say, yeah, these cows would be deficient. We need to, we need to look at their nutrition program to find out why are they so low say less than 30, less than 20 nanograms per mil.
Corwin (40:14):
But there's what I've seen from typical herds feed and say between 30 and 50,000 units, there's quite a bit of variation there. You know, say from an average of 40 nanograms for a herd, 40 nanograms per mil for a herd to another herd feeding a similar level that might be at 80 to 90 nanograms per mil for the concentration, and it doesn't seem to be related to vitamin D nutrition. That's probably a genetic factor. Some other factors taking place there that would explain that. So you'd have to be really careful on people taking those numbers and saying, well, we just need to increase supplemental vitamin D3, and so we, we need to build our, our pool of evidence in that realm at the same time. It would be, it, it's very useful in terms of is there a, a vitamin D deficiency problem taking place there that we really need to look in this closer? Well, you get above that, it's say, 40 to 50 nanogram per mil range. You'd have to say, okay, it's vitamin D deficiency, not a problem here. There's something else to, to consider what's taking place.
Scott (41:29):
All right, bill, as we transition into our last call, any final thoughts that you'd like to leave with the audience?
Speaker 2 (41:36):
Tonight's last call question is brought to you by NitroShure. Precision released nitrogen, NitroShure delivers a complete TMR for the room and microbiome helping you feed the microbes that feed your cows. To learn more about maximizing microbial protein output while reducing your carbon footprint, visit balchem.com/nitroshure.
Bill (41:57):
I guess, you know, vitamin D is a vitamin that had almost no research for probably 30 or 40 years. So it's, good we're now seeing some, new stuff cuz we need, that's a vitamin that's been under researched in dairy cattle.
Scott (42:12):
Clay, any key takeaways you'd like to share with us?
Clay (42:16):
Yeah, I'm, I'd, I'd be curious, you know, mode of action of what, you know, what's leading to these milk responses and are you doing more work in this area?
Corwin (42:27):
Yes. still working on this. In fact, I have a U S D A grant funded now, not necessarily to look at the cow responses, but more so the, the long term effects, you know, from maternal and needle natal vitamin D nutrition, focusing on the immune system, so still be working in this area. So ongoing work in that regard. So hopefully we start to narrow this down a little bit more of understanding the mode of action and nail it down a bit more too of the most effective amount. Particularly when you look at, you know, economic returns, what's gonna be most effective. Right.
Scott (43:06):
Corwin, any final take home messages for our audience?
Corwin (43:11):
Well, I didn't come prepared to think of that one
Scott (44:31):
Excellent. Bill, you outdid yourself. Again, this is another great paper. Thank you for bringing it to us and, and thank the all turn on me
Speaker 2 (45:02):
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