Guests: Dr. Bill Weiss, The Ohio State University and Dr. Rich Erdman, University of Maryland Tonight we finish the conversation on the new NRC with two legends in the industry. We’ll first focus on macro minerals, trace minerals and vitamins, but then we’ll also put a bow on the NRC series and wrap it up for our listeners tonight.
Guests: Dr. Bill Weiss, The Ohio State University and Dr. Rich Erdman, University of Maryland
Tonight we finish the conversation on the new NRC with two legends in the industry. We’ll first focus on macro minerals, trace minerals and vitamins, but then we’ll also put a bow on the NRC series and wrap it up for our listeners tonight.
Dr. Bill Weiss says the new NRC defines “requirements” which was never done in past NRCs. They give a specific number for a specific population which is a large improvement for the reader. (9:55)
Dr. Rich Erdman discusses the animal’s needs or requirements in order to maintain herself. He discusses the availability of vitamins, trace minerals and macros as well. (19:50)
Dr. Bill Weiss discusses trace minerals and the factorial system used in the new NRC for these minerals such as manganese, iron, selenium and iodine. He discusses the copper and zinc data found in the 2021 version are based on the maintenance requirements of the cow. (33:33)
Dr. Rich Erdman stresses there is still a need for more specific data on the availability of supplements and feed. (50:10)
Dr. Bill Weiss discusses challenges for the next editions of the NRC (now NASEM) such as finding young scientists specializing in minerals, funding and the USDA recognizing that minerals are important and should be focused on. (1:05:53)
This concludes our series on the 2021 8th Revised Edition of the Nutrient Requirements of Animals. If you’d like to pre-order a copy and receive a 25% discount, visit Balchem.com/realscience and click on the NRC series for a link and the discount code.
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Scott Sorrell (00:00:19):
Good evening everyone, and welcome to the Real Science Exchange. The pub cast where leading scientists and industry professionals meet over a few drinks to discuss the latest ideas and trends in animal nutrition. Tonight, we finish our discussion on the new Dairy NRC with two legends in the industry. Tonight's episode will have a dual purpose. We'll have an in-depth conversation about the macro minerals, trace minerals, and vitamins chapters; but then we'll also use this as a series wrap up, and we'll discuss a little bit about the history and the future of the Dairy NRC and implications that it may have for the industry. Hi, I'm Scott Sorrell, one of your hosts here tonight at the Real Science Exchange. I'm happy to welcome Dr. Bill Weiss. Once again, Bill, you're becoming quite a frequent guest here at the exchange, and we appreciate that. Bill presented the vitamins and minerals chapters previews on the Real Science lecture series a few weeks ago. Bill's also spent several decades researching vitamins and minerals, and he also served as vice chair on the new Dairy NRC committee, along with his guest tonight, Dr. Rich Erdman. Dr. Weiss, welcome back to the Exchange. And I know you know the drill. So what are you drinking tonight? And then after that, can you give us a kind of a brief overview of the process that you used in creating the vitamins and mineral chapter for the new NRC?
Dr. Bill Weiss (00:01:42):
Yeah, well thanks Scott. It's good to be back. Tonight's beer is, I try to stay local, it's a Wiedemann's Bohemian special brew.
Scott Sorrell (00:01:51):
I haven't heard that in years. That's awesome.
Dr. Bill Weiss (00:01:54):
They quit and then they opened back up, so I guess it's been open again. The new Wiedemann's has been back about five years.
Scott Sorrell (00:02:02):
That's awesome.
Dr. Clay Zimmerman (00:02:02):
Wow.
Dr. Bill Weiss (00:02:04):
It's quite tasty. It's been a long time since I've had one. It's not as good as two east was there another beer he drank last time called a Tuees,[SS1] but it's good, close. Tonight, well with minerals and vitamins, that's one of the more challenging areas of NRC. One, there's just not a ton of data. You know we can't do these sophisticated statistical analysis they could do for energy and protein and growth. We just don't have enough data to look at intake of minerals against responses. So it's a challenge on that way. We had to do a lot of extrapolation. You know, a lot of these studies, especially vitamins, there's the control with no supplement, and then they feed some well. And you know, where that response happens,
Dr. Bill Weiss (00:02:51):
it might happen right where they pick, or it might be better doubling it, or it might be just as good as they cut it in half. We just don't know. And another big challenge with this, or I guess I don't know if challenge is the right word, but you know, a lot of software comes up with their own energy and protein systems. But a lot of them, I'm going to say most of them, use NRC minerals and vitamins. That's, they take these equations and put them into their software. So it's a big responsibility because a lot of people are going to be using these, even if they don't think they're using them, they really are. It's difficult, but it's also very important.
Scott Sorrell (00:03:30):
Good. Thank you for that Bill. We mentioned your guest that you brought with you earlier Dr. Rich Erdman, would you mind introducing him?
Dr. Bill Weiss (00:03:38):
Happy to, especially since OSU beat Maryland. It was a very good game.
Scott Sorrell (00:03:43):
More than a beating.
Dr. Bill Weiss (00:03:43):
Yes, I was being polite. Rich Erdman served as a co-chair of the NRC. He served also- the reason they picked him for this- he was on the 2001 committee as well. He's been at Maryland I can't tell you how long he's been... I met him, he probably doesn't remember this, but I actually met him when I was in graduate school. I had went out to Beltsville and to see Dr. Aldo, and you were there and I met you. So I've known you a long time. You've retired a few years ago from Maryland. Now he's just enjoying retirement as he works on the NRC. But he's done tremendous research in energy, body composition, a lot of mineral work, especially the macro. Some vitamin work, especially more water solubles, but he's one of these people that has a broad area of expertise. Today, a lot of people get very, very specialized, but Rich is one that knows a lot about a lot of things. So I'm glad he could join us tonight.
Scott Sorrell (00:04:50):
Yeah, we are as well. It's an honor, Rich, to have you here joining us tonight. Can you kind of explain how you got involved with the NRC, and I think kind of Bill just said that it was because you were involved with the first one. So maybe tell us how you got on the first one. And then how long have you been working on this 8th revised edition?
Dr. Bill Weiss (00:05:07):
Forever!
Dr. Rich Erdman (00:05:17):
I was hoping you wouldn't ask that question. First NRC, we started in... was it '97?
Dr. Bill Weiss (00:05:22):
Yes, for 2001.
Dr. Rich Erdman (00:05:26):
Yeah, for the 2001 version. I mean, you know, the way people are selected for the committee is they get nominated. Because somebody had nominated me, I have no idea. Yeah, I didn't nominate myself. My first real dealings with the Bill were really , in terms of working with him professionally, was on that committee.
Dr. Rich Erdman (00:05:50):
Of course I've known him for a longer period than that. When the new one was formed, we were asked to serve as co-chairs on that committee.
Dr. Rich Erdman (00:06:01):
You know, Bill actually worked in, has worked in several areas, also. He has as a lot of general knowledge, a lot of background, and he has good connections within academia and also within the industry. So pretty well known.
Scott Sorrell (00:06:25):
Good. Thank you for that. I also have the pleasure to welcoming back my cohost, Dr. Clay Zimmerman. Clay, are you drinking anything delicious tonight?
Dr. Clay Zimmerman (00:06:36):
I am enjoying some water tonight.
Scott Sorrell (00:06:39):
That's good. You need to stay hydrated, Clay. Anything exciting that you're looking forward to in our discussion tonight?
Dr. Clay Zimmerman (00:06:45):
A lot, actually. I mean the Discover Conference was great. You two both need to be commended for the job you did. We're certainly losing a lot of people like you from the industry now with the broad backgrounds that you both bring. So I'm really looking forward to this discussion. So thank you both for joining us. Scott, what are you drinking tonight?
Scott Sorrell (00:07:09):
We'll Clay tonight I'm switching it up. I'm drinking a beer like Bill is. I'm drinking a Stella. Rich, to get us started. Can you give us a little history of the Dairy NRC? You know, how did it get started? Why did it get started? When did it get started? Those kinds of things. And what was the intended purpose when it first began?
Dr. Rich Erdman (00:07:32):
It started actually in 1940, but it was part of the war effort to increase food production for the war. Of course then, Europe was on, they were flat on their back after the war. And they developed requirements, and they were requirements set for all of the domestic livestock species, including horses because they were an important animal at that time.
Dr. Rich Erdman (00:08:02):
Well, first one's were in '45 or '46. They had not ever had all species then come out at one time, but they were fairly close. It wasn't very long, I think the first Dairy NRC was 30 pages, something like that. A lot of effort spent on explaining nutrient deficiencies. It was supervised by the National Academy.
Dr. Rich Erdman (00:08:35):
And then over time, initially they would have a new one out every five years. And it went that way, and then they changed from- originally, they were called "nutrient allowances". And then, I think maybe after the second or third go around, they changed it to nutrient requirements.
Dr. Rich Erdman (00:09:01):
And so edition is the 8th edition of the Nutrient Requirements of Dairy Cattle. You know, and the intent was to convene a committee of experts, and essentially these are feeding standards that are used are news as a basis for feeding cattle, not only in the US but also worldwide. These are most highly cited publications in terms of the dairy cattle community, by far.
Scott Sorrell (00:09:44):
Well. So kind of following up on that. You said it transitioned from allowances to requirements. Bill, can we talk a little bit about requirements, and how are they determined today?
Dr. Bill Weiss (00:09:55):
The thing about this new book that's coming out is we actually define what we mean by requirement. For several issues, we just said this is a requirement, but we never said whatever requirement was. So in theory a requirement is when we say the calcium requirement is "X", that means for a specific type of cow- this isn't for an average cow, it's for the specific type of cow- so much body weight, so much milk. The average cow doing that needs this much calcium. That's what it is. So half the cows would need more, half the cows would need less. Again, it's not for all cows, it's the cows within that very specific population. And the way we've gone very much toward factorial because it's easier to quantify. So what we try to do is the cow needs this much calcium to put in milk, and the cow needs this much calcium to put into her fetus. This much calcium, if she's growing a little bit, and then there's these maintenance functions, which are lost in feces or urine. And the cow needs so much calcium to replace these inevitable losses.
Dr. Bill Weiss (00:11:12):
And if we just add them up and it's so many grams a day is how much she has to absorb. For, again, the average cow, half the cows need more than that. And then we have to come up with how much calcium a cow can absorb under these conditions, and we divide the requirement by absorption to get how many grams you have to feed. So that's in theory how it works, and as we go through tonight's discussion, that works pretty well for most macros. There are still a few exceptions, but this factorial approach probably isn't- we're missing things I think for the traces and clearly for the- it will not work for the vitamins at all.
Dr. Clay Zimmerman (00:11:53):
What's the difference between a requirement and adequate intake?
Dr. Bill Weiss (00:11:57):
Well, it works best for vitamins. Like I said, if you have an experiment-. We did a lot vitamin E studies, and we'd feed, our classic experiment would be no supplemental vitamin E, and a thousand units. That's what we fed. And we'd see nice health responses from a thousand units. So we would say adequate intake is a thousand units, you would get improvements in health and it may not be, you know, you might get twice as good for 2000, or might work for 500. So it's really when you...there's a lot of uncertainty on the actual number. That's what we really tried to know is that, we know they need it, you should feed what we call the adequate intake, but we're not sure if that's exactly right. I think that's a big improvement, even though the numbers, like you look at the vitamin E requirement in 2001 is the same as the vitamin adequate intake in 2021. But again, it just makes the reader aware that there's some uncertainty associated with these numbers.
Dr. Rich Erdman (00:13:00):
And that definitely came from the National Academy of Medicine. When they went from the system based on daily allowances to what we call dietary ration intake, and you went into that DRI system and one of the categories is an estimated average requirement. That's when we say requirement, that's what we mean. And then they also have a DRI and that was the requirement plus two standard deviations around the requirement.
Dr. Rich Erdman (00:13:46):
And then they have adequate intake where they can't really define what the average requirement is. You know, there's not enough data to precisely estimate that. Or, they don't have an estimate of the variation in requirements. So when we say requirement, we have the average requirement, but almost always we also have in an essence of variation around that requirement.
Dr. Bill Weiss (00:14:20):
You know, even in the human system for a lot of the minerals, they don't have a standard deviation. They really don't. And they just take the variance for energy metabolism, which is CV at 20%. And that's their safety factor is basically 20% above the estimated average requirement. That's what they say you should shoot for. And I think that's a good idea for dairy, too. But that's not included in the NRC. We have no safety factors. So the user has to, in many cases, feed more than NRC just because of the normal population. Or normal distribution. They need to be reasonable in the amount. Minerals tend to be overfed quite a bit.
Dr. Rich Erdman (00:15:00):
Yeah. I would say that for many of the nutrients, that's correct. Things like energy and protein, that overfeeding for energy isn't disastrous. You're not going to have health implications from that.
Dr. Rich Erdman (00:15:05):
(15:20) And protein, it's just too expensive to do that. Whereas as for, certainly for the micro and minerals and the vitamins, you're not going to amass much cost if you start doing that.
Dr. Rich Erdman (00:15:05):
(15:41) But I think the main thing is for people to realize that that number, when you say adequate intake, that's our best estimate. its not precisely defined.
Scott Sorrell (00:15:57):
Gentlemen, I'm curious talking about dietary requirements. Are there, do you guys have a list of nutrients for which there is a biological requirement, but you just don't have the data to be able to put an NRC number on it? And just curious if you have that list, is that something you plan to pass on to the next committee?
Dr. Bill Weiss (00:16:19):
Yeah, there a lot of nutrients or maybe not-nutrients that affect milk production, for example, but that doesn't mean you have to feed it just because you get more milk doesn't mean you have to feed it. But things like biotin is maybe not a dietary required nutrient because the rumen can make it, but the cow has to absorb biotin. And it often increases milk, so that would be one that maybe we need to, we need to-. Well to get biotin into this, we need to be able to estimate synthesis and rumen destruction and all that, which is not easy. Chromium is one that very often they respond, but how much chromium does a cow need? I have no idea because we don't know basal concentrations. Choline could fit in that situation, and maybe niacin. So there's a lot that, again, we know their nutrients, but we really don't know if you have to feed it or supplement it. And if we have no idea on how much to supplement, we can't in good conscious say, this is the requirement. Because obviously in a lot of cases, cows don't need it because there's enough basal.
Dr. Rich Erdman (00:17:27):
And Sulphur is simply a rumen requirement, that's all it is. Cobalt is for making vitamin B12.
Dr. Rich Erdman (00:17:44):
If a cow, per se, doesn't have a need for cobalt, but it needs it to make B12. So there are certain nutrients also, they're not necessarily needed by the cow itself, but rather for rumen function or for reasons than meeting a requirement on the cattle.
Dr. Bill Weiss (00:18:15):
The DCAD can fit well into that as well. Because we get nice responses to increasing DCAD, but you don't have to do that to still get milk production, or high milk production. So macros would fit into that category as well, some macros. I think magnesium fits especially for the pre fresh-cow on risk for hypocalcemia. We can't figure out why. We use the factorial system, we will come nowhere close to what meta analysis says you should feed for magnesium and a pre fresh cow. We can come nowhere close to that. So there's some other functions we don't know what's going on, or uses of magnesium. We just don't know.
Dr. Clay Zimmerman (00:18:57):
So which response variables, as a committee, which response variables are you looking at to come up with the requirements or adequate inputs?
Dr. Bill Weiss (00:19:07):
Just starting in on it, and then I'll turn it over to Rich. But again, remember for most of the macros it's factorial. We just add up things we can measure, like milk; calcium. We can measure that. So just an adding up of all these things. For the traces, we tried to do that for some. Cobalt, we were talking about that. That we used liver B12 concentrations as a response. Serine and homoserine. So there's things, metabolic responses, that we could use. For some I might've been pla-. For vitamins, might've been plasma levels. Some of these, that's one of the hardest things is finding a good response variable.
Dr. Rich Erdman (00:19:50):
I think for things like energy, and protein, and amino acids, probably not as well, but we're doing better. You simply identify these losses that occur. You know, think like what's needed to maintain the animal. What's needed for- most appropriate for [SS2]growth and milk production.
Dr. Rich Erdman (00:20:22):
And you add them up, then you have a pretty good idea of availability for the diet, and that's how you come up with them. But I think what the problem is that that doesn't work well, and we're talking about the vitamins and trace minerals and, and some of the macros. When you don't have a good index of availability, that's when it gets harder to define the requirements.
Dr. Rich Erdman (00:21:00):
That one is you know.... I think I made a statement at the Discover Conference that nutrients that have high availability, generally, you have a pretty good certainty on the requirement. Whereas things that you have uncertainty about the availability, or they're low, those you have much lower certainty as far as what the animal actually needs. And so it just so happens that of all the nutrients, the micros and the vitamins, those are the ones who have less certainty on availability. You can't really define the requirements as well.
Dr. Bill Weiss (00:21:53):
And so some of them, a lot of the macros are 50% or more available. But some of these micros are less than 1% available. And so, you know, if you go from 5.5% available to 1%, I don't even know if we could measure that difference experimentally. But that would double, or in this case half the dietary requirement. And we can't even measure that. When the denominator has a really small number, a small change makes a huge effect on diet requirements.
Scott Sorrell (00:22:24):
It makes perfect sense. Talking about macro minerals. Bill, perhaps this question's for you, what are some of the biggest changes that took place in the macro mineral chapter?
Dr. Bill Weiss (00:22:35):
Well actually I'm going to let- Rich did a lot of the work on macros, so I'm going to let him address, and then I might follow up on a few things. But he was responsible, so he can be blamed for most of that.
Scott Sorrell (00:22:47):
All right.
Dr. Rich Erdman (00:22:48):
On the electrolytes, I think did a much better job. We had good digestibility data on cow's varying levels of these sodium, potassium, and chloride . And a few things that came out from that. One is in the availability of those three minerals is exceedingly high. In two cases, sodium and potassium, we sent, and this is estimating here, 100%. And for chloride, 92%, but I wonder about that.
Dr. Rich Erdman (00:23:30):
So absorption is not a problem with those. And then, you know, we know what's in the milk. Much better definitions of the maintenance requirement. And most of them with- almost all of them- which is no loss [inaudible] requirement.[SS3]
Dr. Rich Erdman (00:23:52):
And we have, I'd say, a very good handle on the amount of those three elements. As far as what is needed for various functions, and the amount needed in the diet. And I said, when availability is high, that just removes any error in terms of determining a requirement. We need to make some adjustments in the amounts of some of those. In milk, that's another thing.
Dr. Rich Erdman (00:24:06):
(24:26) Sodium requirements were about 40% lower than the previous version, mainly because cows have less mastitis than they used to. And fluorine also. That was changed, but it terms of overall amounts of those, it's really not much different. In terms of what you would need.
Dr. Bill Weiss (00:24:48):
I don't think the numbers changed much, but like you were saying, I think we're much more accurate on the biology of what's happening. As it is, there are these differences, that just we fit, we fit much better on biology. Which I guess theoretically would mean when you get more unusual diets, these equations should work better than the other ones, or the older ones. What Rich brought up to me when we started this, you know, the easiest thing to measure is milk. It's easy to sample. We should have had great estimates on lactation requirements. And for a lot of minerals, those changed probably more than anything else. Rich brought up mastitis for sodium and chloride. It changed a fair amount for calcium. Changes for some trace minerals, it was by a factor of three or four, so huge differences. And it really surprised me. I was thinking, "Oh those, we've known those for 50 years. We don't have to mess with them." But there was big changes on that.
Dr. Clay Zimmerman (00:25:52):
I found that Interesting how you estimated the milk calcium requirement. Can you explain that?
Dr. Rich Erdman (00:25:57):
Well, I mean, so I worked on that one. The previous version was based on some estimates from Britain in the early 60's. Fortunately there had been some pretty major studies done where they looked at bulk tank calcium levels in California. I think ____ was involved with one of those[SS4].
Dr. Rich Erdman (00:26:21):
And when the calcium, the amount of calcium. They were based on breed only, and they were finding higher than what you actually-. Sorry, That the measured amounts using a herd bulk in California with much lower for calcium than it had been using the previous NRC.
Dr. Rich Erdman (00:26:50):
And so I started looking at the data, and then, you know, okay, where is calcium in milk, same as for phosphorus, most of that in associated with the calcium micelles. And so the calcium micelles are calcium phosphate salt, and they're associated with [inaudible] .[SS5]
Dr. Rich Erdman (00:27:22):
And so we started looking at that, and we kind of considered that for both calcium and for phosphorus, that milk protein was probably a much better predictor of calcium and also phosphorus need than, you know, breed test. And when you incorporate in that, we found that most of the differences in breed were due to differences in the protein content of the breed, and that made sense.
Dr. Rich Erdman (00:27:59):
So that was why that was made. And we got rid of that over prediction that was in the last one. I remember reading the last NRC on the calcium amount in Holstein and Jersey milk, and they were 1.2, 1.4. I'm like, nah, that's not right.
Dr. Rich Erdman (00:28:23):
Because if you buy milk in the store, or you look up calcium concentration[SS6], it's never that high. It's usually about one gram of calcium per liter of milk. That's pretty standard, it doesn't vary that much. But that's how that one changed.
Scott Sorrell (00:28:46):
You guys talked a little bit about mineral bioavailability and the impact that that has on the formulas. Is that because the source of the mineral that we're using? And if so, is there anything we can do to improve the bioavailability of those sources, or should do?
Dr. Bill Weiss (00:29:04):
Well, the source is a biggie. The supplements, you know, the mineral supplements can vary a lot in availability. Feeds: we don't know how much, because how do you determine the availability of calcium in soybean meal when you have to feed it a mixed diet? On feeds, I don't think we know nearly, nearly very much. And I, I really don't think that's important. We do need to do some availability of a variety of diets, and see if there's much diet effects. But whether soybean meal calcium is more available than canola meal, that's not important. The source is a biggie, how they and then I guess the other thing is, is especially if, more for the micros, but some macros is the antagonist. You know, what else is in the diet that can affect availability? The classic is potassium affecting magnesium, sulphur effecting copper. So source, and then I'd say just diet composition would be two big ones. We have no idea on genetic, on cow variation, no idea whatsoever.
Scott Sorrell (00:30:13):
Any, any ground unplowed yet, then on the macro minerals, before we transition over to the trace mineral requirement?
Dr. Rich Erdman (00:30:22):
I would think phosphorus. Because phosphorus, we changed the system, but on the amount, I'm not sure, Bill, how much that changed.
Dr. Bill Weiss (00:30:36):
On average it basically is the same. But again, we're hoping to incorporate more sources of variation so that on stranger diets, we can be more accurate and less overfeeding. And I think you'll notice on a lot of these things for an average diet, an average cow didn't change a lot. But it's what we think is with these better equations, when you start feeding less average diets and less average cows, it should work better.
Dr. Rich Erdman (00:31:05):
I think with calcium, there was quite a change in availability. For some reason the last committee made some assumptions on, you know, the availability of these, let's say, calcium supplements. They are based around either calcium carbonate or calcium chloride. And they just had those estimated too high. And so, essentially what you saw is that guys were assuming the average available was the 60%. Those went back down to 45%, which was kind of where we were I think in the '89 version and the previous ones. Then this time we actually had data to evaluate. To see how the availability of the diet in general compared to sunny[SS7], and I think more close to the reality. So we're probably going to see a little bit more calcium than what was estimated now. On the other side, milk calcium hasn't really declined, we just know it was lower than what they estimated. The requirements went down, and that's why they _______________________________ [SS8]total calcium requirements didn't really changed all that much.
Dr. Bill Weiss (00:32:42):
The one macro that probably changed the most was magnesium. And I think when the last NRC came out that spurred a lot of research. So we had a ton of data. They did not have in 2001, so we don't want to denigrate that too much. Because we could do things they could not. And so we have much better absorption coefficient data than they could ever hope to get. And again, when you get better absorption data, you can better estimate these other things as well. So that one is probably the biggest, and could almost double in some cases of the dietary requirement. But again, it's just because we could do so much better a job because we had so much more data.
Scott Sorrell (00:33:26):
Very well. Let's kind of transition over to trace minerals then. And Bill, did you write that chapter?
Dr. Bill Weiss (00:33:33):
The whole committee is responsible for it, for the good and the bad? But we were major contributors to that. Again, we tried to follow this factorial approach and for copper and zinc, actually there's enough data. I think we're pretty good on the factorial system. For manganese, iron, selenium, iodine; it's an adequate intake, clearly. So again, we tried to look at the copper in milk. Which again, in the 2001, they had a level like 0.15 milligrams per liter. And when we summarize the data, we could find it was down around 0.03 or 0.04. So a huge difference in that. And I don't know where, I couldn't dig up where the old one came from, but with the new one there's a lot of, or should say, a fair amount of data. And then the endogenous fecal...
Dr. Bill Weiss (00:34:31):
So those, I actually call those requirements. I don't call those adequate intakes for copper and zinc. And we have decent for trace minerals, absorption data. And the copper again was one of these where, and we did spend a lot of time on copper because there's internationally, there's a major concern on copper. And so we, we worked hard on that. And for again, for the average cow, it hardly changed. But because maintenance changed one way, absorption changed a little bit, and milk changed a lot so that at the end of the day, the numbers were almost identical. But for a high producing cow, it's a lot lower in 2021 because milk doesn't have as much copper as they thought. So that was down about, would be about 40% less for a cow milking a hundred pounds using the new system compared to the old one.
Dr. Bill Weiss (00:35:24):
But dry cows went up a little bit because the maintenance went up. And then zinc is a little higher. I can't remember, maybe 10%. But again those two, I consider requirements. The rest, you know, manganese, you could count on one hand how much manganese research has been done in the last 20 years. Iron, only about one finger probably is all you need. Selenium, there's a lot of data on selenium, but because of regulations and other issues, there's not a lot we could do on that. You know, we might come up with a different number, but you still gotta obey the law. So the traces again, it's easy to do the literature search cause there's not a ton of data, but we did everything we could. And they're clearly better, even though the numbers, a lot of them... Manganese did change a lot, but the other ones you'll notice on average didn't change a whole lot.
Dr. Clay Zimmerman (00:36:20):
Bill, did the committee address maximum tolerable levels or minimum levels?
Dr. Bill Weiss (00:36:28):
Well we, and again, this first chapter, which Rich wrote, I'd strongly recommend everybody reading that because it discusses all of this stuff. Upper limits or maximum tolerable, however you want to define it. And so in the chapter where we had adequate data, we would say, and I can't remember the numbers now, but we would say there's data saying if you feed more than 30 milligrams per kilogram copper, you increase the risk. And again, I'm not swearing to that number. But we tried to include data on maximum tolerable levels. But like Rich started this discussion, is people got to remember there's variants on that number too. And it's plus or minus. It's not always, you know, on requirements, everybody wants to overfeed and ignore the minus, and on the upper tolerable level, they forget to minus. So there's a lot of uncertainty on that number, too. So you want to stay well south of upper tolerable limits, but we did, we did address it as well as if we could, if there was data.
Scott Sorrell (00:37:32):
What are the kind of basis, the changes, what are some of the practical implications that a nutritionist might want to take into account?
Dr. Rich Erdman (00:37:40):
It was a lot of work. And like, I feel like the lumbers we have are a lot better as far as estimating the requirements. But in the end, I found myself at the end of the session saying, well, you know, maintenance went up, milk production requirements went down now, and in the end they really hadn't changed that much. I mean, that's kind of what it was for many of the macros, except for magnesium and perhaps for calcium. So I think mainly knowing why things are the way they are and having a better understanding of where things are being lost, rather than it's going to dramatically change how a practicing nutritionist would see cattle. And that's kind of what, at least on the macros, that's what I walked away from. I feel more confidence in what we have. Absolutely more confidence.
Dr. Bill Weiss (00:38:57):
And I think users are a real, you know, we have a lot more confidence in that number, which means they should have more confidence in the number. And they should reduce the overfeeding. I mean, when you don't have confidence, you often over feed. These are better, and they'll still think you have to vary off and and overfeed, but not overfeed as much. And again, I think these new equations it's when we get away from average. That's where I think the difference, like, you know, if you had a 125-130 pound cow, this lower milk calcium would make a big difference. And again, as we deviate from these averages, I think you need to have more confidence in these numbers that would feed the average high-producing cow.
Dr. Clay Zimmerman (00:39:47):
So are there key changes on the trace minerals side that that nutritionists should be aware of?
Dr. Bill Weiss (00:39:56):
Well, the, the biggest change in the number was manganese by far, but I think everyone, and again, there's very little data and I think the old committeee put a little bit too much emphasis on one or two availability coefficients. And when the availability coefficient is 0.5% and they used 1, that basically cuts the requirement in half. So it's a very small, almost unmeasurable difference. But I think most, most nutritionists say we can't go this low. And so the new numbers will be closer to what people are feeding. And the copper again, there's I get, when I was still working, I'd get calls at least once a week on excess copper. Not on inadequate, but excess. And so again, I think these new numbers that on average are going to be the same, high producing cows will be lower. And I think again, you know, I tell them how much I think they need, and they'll say, "Oh no, we can't go that low." And now I'm hoping, they'll say, "Oh, I think maybe we can go that low."
Dr. Rich Erdman (00:41:07):
Yeah, I think the only one I remember. Cobalt, that got doubled and to be honest with you, that change was based on some work done in Germany with growing cattle. But that work was so well done. They measured all the metabolites associated with B12 metabolism. And they fed at multiple feeding rates. It was so clear that, the previous was 0.1 milligrams per kilogram. And it's still a free element, it's very inexpensive. But I feel very, I mean, certainly I didn't see more cobalt than that, but I think a minimum of 0.2 is needed. Then others like, you know, something like I worked on iodine, and oh my goodness. All of that data, it goes back to Bill Miller at Tennessee and Neil Hanford. This was done in the 50's and 60's, and that is just wide open..
Dr. Rich Erdman (00:42:32):
You know, when you really. I can often see how they're fed, but as far as a requirement, it's just almost impossible to determine the amount. There are a lot of things like, for example, going back to calcium. The availability data for calcium is bad. There are tools now that we have that before, the only way you could do it was using radioisotopes, and you can't do that anymore. But now you can use single isotopes. So there's a lot of opportunity there, I think, for most of the base elements with the option to do it that way where we didn't have before.
Dr. Bill Weiss (00:43:27):
Yeah, you gotta get somebody that can sponsor. It's expensive research. But we have techniques now to do it. We just got to get somebody who's willing to pay for it.
Scott Sorrell (00:43:38):
Do we have any significant revelations related to vitamins in the new NASEM?
Dr. Bill Weiss (00:43:44):
Again, we only have adequate intakes and we only have the fat solubles. I do want to put a little plug in for the actual book, not just the software. The book has a lot of good, is an excellent reference. And there's a very good section on water-soluble vitamins, a good lit review. So I'd encourage people to read the book, not just use the software. We don't have requirements or adequate intakes for their water solubles, but functions, responses, all this is discussed in pretty good detail. On the fat solubles, they were tweaked, not changed. Milk is a pretty good source of retinol. And these higher, most of the studies were done back when cows were averaging maybe 70 pounds of milk. And so at a hundred pounds, you got to start accounting for this retinol lost in milk. So that was added into the equation.
Dr. Bill Weiss (00:44:37):
So we account for that, so as I said it's not a factorial, but pseudo factorial. Vitamin E, the only new data on that was with pre fresh cows on postpartum health. A lot of metritis data, a little mastitis. So we bumped up a pre fresh requirement. And on vitamin D, the reason we changed. And they old NRC, and this goes back, I don't know how long, but it's always been calcium. You feed enough vitamin D to prevent rickets and maintain blood calcium, and that's all they needed. And especially with humans, you hear, you know, vitamin D can do almost anything. I don't know if it can do quite as much as people said, but it's well beyond calcium. And so we use the cutoff based on 25 hydroxy vitamin D. Maintaining, I think it was 30, don't don't hold me to that number. But a certain plasma level of 25 hydroxy D, and on studies that have been done say most cows fed the old NRC will meet that minimum blood level, but a substantial number didn't. And so we bumped that up a little bit again so that at adequate intake, most cows would maintain blood levels at the 30 nanograms or whatever it was if you feed these new levels. So a tweaking more than anything, but still clearly adequate intakes, not requirements.
Scott Sorrell (00:46:06):
Bill, wanted to say, just kind of a follow-up to your discussion about reading the new Dairy NRC. You can order your, you can, pre-order your copy by going to Balchem.com/RealScience and get a 25% discount. Just click on Dairy NRC there. So just kind of, there's your way to get the booklet and a discount.
Dr. Bill Weiss (00:46:29):
Before I forget here, I just want to mention this is for most nutrients, you know basal ingredient supply counts. The copper in the corn counts, and the calcium in the alfalfa count. And people tend to forget that sometimes, but for the vitamins, we don't count. Because people don't measure their beta carotene in plants and they don't measure the tocopherol. So we don't count that. And for some of these traces, cobalt for example, we really don't count the cobalt in the feeds because we don't know how much is in there. So some of them, selenium, we don't really count what's in the feed. So pay attention to that too. But in general, count what's in the base. That's in the absorption coefficient and so on. So it's total diet mineral, it's not just supplemental.
Scott Sorrell (00:47:28):
Bill, do you find a difference in the bioavailability of the minerals found in the plants versus the supplemented versions?
Dr. Bill Weiss (00:47:39):
From the data we have it used to be, when you talked to nutritionists, the stuff in the feed wasn't very good. The stuff in the supplements was good. And from the data I've been able to dig up, it's probably just the opposite. A lot of this stuff in the feeds is relatively high. The stuff in the supplements still could, might be good, but it's not as good as the what's in the feeds. And a lot of this makes sense. And, you know, it's like the calcium in plants is very soluble. It's been taken up by the roots and it's soluble. The calcium in limestone isn't so soluble. And magnesium. Some of this makes a lot of sense that the plants actually can be a pretty available source of mineral.
Scott Sorrell (00:48:28):
Clay. Any thoughts on this area?
Dr. Clay Zimmerman (00:48:31):
Bill, I know you get this question a lot, but what about what about differences in increased mineral absorption by source?
Dr. Bill Weiss (00:48:42):
Well, it's highly related to solubility. So the sulphates and chlorides are going to be better than the oxides. The organics, that's, you know, we can measure, I think adequate. Well again, to measure the absorption of any of these trace minerals is very, very difficult. So the commercial companies out there don't know, I'm going to say, they do not know the actual absorption. They might have what we call relative absorption. So they compare response to copper sulfate. Their product might double the liver copper compared to copper sulphate, so they say it's twice as available. And I think that's a reasonable thing, but you still don't know what the availability of the copper sulfate is. So it's twice of something, but you don't know what the something is. So there's a lot of unknown. And for some of these minerals, we don't even know what to measure. You can't even do relative availability. Manganese, what do you measure? I don't know. So that's still a major issue on a lot of these is just how available this stuff is. Because again, it's not just measure what goes in the front end of the cow and what comes out the back end. That doesn't answer the question. So it's, it's tough to measure.
Scott Sorrell (00:50:04):
Rich, any big areas that we've left uncovered so far on these three sections?
Dr. Rich Erdman (00:50:10):
Well, we've talked about, spent a lot of time on availability. If we could look into the future, I think that that's an area with really need a lot more specific data on supplements and on availability in feeds. I remember having a discussion about calcium and how available calcium was in, let's say a cereal grain.
Dr. Rich Erdman (00:50:18):
(50:47) And we realized quickly that very little diet calcium comes from cereal grain. So it doesn't matter if you're off. But things that are major sources, you know, those are, those were lacking, and the major sources are. For example calcified calcium you would need supplements, and maybe some of protein supplements to go along with that. And I think, again, we've talked about this alot. But I think that availability was the biggest challenge of going through all these minerals. That was where most of the uncertainty was. I think we're doing better.
Dr. Rich Erdman (00:51:41):
But you know, if I was the company let's say that was selling a mineral supplement, then having that availability data is really helpful. And you know, you may find out that you don't need to feed as much of a supplement that is maybe more expensive on a per weight basis but much more available.
Dr. Rich Erdman (00:52:13):
And so, time and time again, I think when we accounted for the losses, I think we know pretty well how much is in the milk. But yeah, availability kept coming back to that. And you know on the traces, how do we know what that number is?
Dr. Rich Erdman (00:52:45):
And then even for a diet, and then let alone a _____ for [SS9]a supplement. That's kind of where I am. If I was working in, let's say I wanted to work in minerals in calcium metabolism. I'm would be going back and working on that availability aspect. That's what comes to mind.
Dr. Clay Zimmerman (00:53:14):
Rich, I know you've done a lot of work in the DCAD area. Do you wanna comment on DCAD and lactating cows?
Dr. Rich Erdman (00:53:22):
Yeah. You know, that was a toughy because we set the requirements, that minimum requirement as the minimum requirement for the individual components of the DCAD. Namely sodium, potassium, and chloride. However, I was not seeing that.
Dr. Rich Erdman (00:53:54):
But here's a situation where you really have to look at the responses of the animal to varying DCAD models. And clearly, you know, if you look at the requirements, you would say using that system that is in the software that your adequate requirements, you give 180 milliequivalents per kilo. I had never seen that.
Dr. Rich Erdman (00:54:16):
(54:27) I had seen a minimum of 300, but our challenge was we couldn't find DCAD, per se. Because it's all dependent on the amount of individual elements, and the amount of DCAD depends on what else is in the diet.
Dr. Rich Erdman (00:54:21):
(54:53) I know that came up at the Discover Conference. I probably didn't answer it very well. But we published extensive meta analysis. And, you know, two responses.
Dr. Rich Erdman (00:55:08):
One is below a certain level of DCAD, intake goes down. No question about it. And above that you'll have two responses. One is a slight increase in milk production, a much larger increase in milk fat content. And so the thing that you're basing your recommendation on is not individual elements, but the response of the cow to that. A comment came up during the meaning about whether we should be feeding an entire DCAD diet during the summer than during the winter.
Dr. Rich Erdman (00:56:00):
And that's another one I wish I would've answered differently. My response was: probably not. You probably are not going to see a higher concentration, but the fact of the matter is that you might even feed an element and the result would be the same in the winter as it would in the summer. I would not _______ [SS10]accordingly.
Dr. Rich Erdman (00:56:26):
In reality, we really didn't have a specific DCAD requirement. I would simply go to the literature, there was a meta-analysis done, and look at the response. And determine how much you want to feed based on the response. And if you feel like your going to get a greater milk fat response, and milk fat is valuable, you're going to feed more DCAD. If the milk fat response is lower and it's expensive, you'll probably feed less.
Scott Sorrell (00:57:06):
Gentlemen, this is the final episode in our series of five reviewing, or previewing, the new Dairy NRC. I'd like to kind of maybe put that behind us and kind of cast our gaze to the future. So as you look to the future, how do you see the new Dairy NRC NASEM evolving? You know, in another 10 years have a brand new, totally comprehensive document, or perhaps could we be taking a look at sections and updating them as needed? Just kind of curious if you've given any of that some thought, and I just kind of threw out a couple of things there just to kind of spur your thinking of what I was kind of thinking through.
Dr. Bill Weiss (00:57:49):
It won't be 10 years. I know it's going to have to go longer than 10 years, hopefully not 20. Unless Rich wants to come back and chair the next one, too. But we talked a lot about that at the end is should we just update what we think needs to be updated. And that's not a bad idea, but does that mean the next book, we have a lot more work on say energy and protein so the next book only has energy and protein and nothing on minerals and vitamins. And that starts making what, or do we just copy and paste the last minerals and vitamins, say nothing was changed and do that. I think some approach where it's more limited in scope is necessary. I do think it's too broad right now and takes too much time. So, and I know Rich when we had one of our first meetings, he kept emphasizing the point. Remember, this is the revised edition. You don't have to rewrite everything, but every everybody did. Except for Rich. I think we do have to limit the scope on what's new because it just takes, you know, this one was seven years. It's just too long. It just takes too long.
Dr. Rich Erdman (00:59:10):
Yeah, I, you know, looking back can think about mistakes that we made primarily in limiting the scope. And yeah, I mean, I kept emphasizing if a section covers what's the available information is, it is, use it. You don't need to rewrite it. I don't think anybody did that.
Dr. Rich Erdman (00:59:31):
(59:48) And that was, I felt it made it more work than it needs to be. I also think that the committee members looked at this and said, "We're only going to have one shot at this. And it might be another 20 years." So they tried to work in as much as they could into this revision.
Dr. Rich Erdman (00:59:31):
(1:00:17) On the human side, what they do is they have is chapters on individual nutrients. And they are all updated at one time. they have separate writing committees for each section. And they stagger them. and I think that's probably more appropriate.
Dr. Rich Erdman (00:59:31):
(1:00:41) I think the new committee on animal nutrition, NAMP, having that group functioning continuously will be a big help. I think the biggest mistake that was made was not limiting the scope of what we were going to do.
Dr. Rich Erdman (01:01:16):
So I'm, I'm proud of the work the committee did. I'm not proud of how long it took. And you know, when I was by myself for some of that. I remember with Bill, that first meeting we had at the National Academy building, and you and I were sitting at front of the table, looking at all these people in front of me.
Dr. Rich Erdman (01:01:52):
I was telling myself, "My God, these people are really smart. What am I doing here?" I knew it was going to be okay. And so you have a tendency to kind of defer to their expertise, and not everyone has that expertise. In looking back at it, I think we should've been a lot more firm, and we tried to be. But some things just kind of drag out, and we didn't need to do that.
Dr. Rich Erdman (01:02:32):
I sometimes tell people I'll probably be dead by the time the next one comes out, hopefully I'm not. But certainly I won't have any involvement in that again. If they asked me, whoever is to do it next time, I'd really council them on limiting the scope of what they're going to do. Pick and choose the most important things, and things that haven't changed much: leave them alone.
Scott Sorrell (01:03:05):
You know, this has been US government sponsored initiative from its very inception. Then obviously driven by US scientists. Does it make sense ever to kind of open it up and then include somehow, I know there's probably a politics involved, but kind of getting a more of an international flavor involved in this. Is that something you all have discussed?
Dr. Bill Weiss (01:03:32):
Well we had Hélène Lapierre from Canada, so it is international, at least north American. And I don't know what the National Academy's rules and regulations are. I don't think they would prohibit that. But I don't know, that's their policy, so I don't know.
Dr. Rich Erdman (01:03:52):
Yeah, I don't see a problem with that.
Dr. Bill Weiss (01:03:54):
I don't see a problem with it.
Dr. Rich Erdman (01:03:55):
If this is a document that's supposed to represent the worldwide industry, having a different perspective would be helpful. It also might make it more complicated, too. I think more about how the committees meet. We didn't meet face to face that many times. I don't know, four times?
Dr. Bill Weiss (01:04:29):
At the most, I don't even know if it was four.
Dr. Rich Erdman (01:04:32):
It;s just a matter of timing when you have your meetings. But no, I don't see where they would be objection to doing that.
Dr. Bill Weiss (01:04:50):
Yeah. It would make things, you know-- a lot of what we do is still very data specific. Our data is Holstein/Jersey. You start bringing, say Europeans in, and now you've got more breeds. They're a grass-based system, we're a corn silage. So it also complicates it so much, a bit more. That would also be an issue. And then, you know, there are other countries have their own systems too. But like I said, there are very good scientists around the world that could definitely contribute to this.
Scott Sorrell (01:05:27):
You know, one final question I kind of wanted to dig into is during the four previous podcasts, and even this one we talked a little bit about gaps in funding, gaps in data. What kind of advice would you give the folks that follow you in terms of filling those gaps in funding specifically, how do we get the data that's needed to fill some of those holes?
Dr. Bill Weiss (01:05:53):
Well, one issue I'm very concerned about as a retired scientist is who's coming up behind us? In the minerals area there are some good young scientists, but not very many. And this is an area that, you know, there's 15 or so minerals, and you can't be an expert in all of them. So that worries me is just, who's going to actually do the research. And then on funding, you know, the companies that make organic minerals and other minerals have sponsored a lot of research, but of course it has to involve, some of it, has to involve their product, which I understand. So I think the USDA needs to recognize minerals are important and, you know, both from right now, we overfeed. So maybe get some better AC data, we you can reduce environmental impact of these minerals.
Dr. Bill Weiss (01:06:51):
You know, some of this animal product livers, which are really high in copper, it can be toxic to humans. So maybe look at that avenue. And then health and welfare, you know, start emphasizing some of this other stuff. But a lot of what is needed is not, I think it's exciting, but a lot of is pretty standard research, but it's needed. And, and so I think some of this has to be at the federal level. And just because it is just across the board, it won't benefit any specific company, you know, benefit the entire-- both producers and users of dairy products. But it's a big issue.
Dr. Rich Erdman (01:07:35):
Yeah. My biggest concern is that so many of new faculty members that are coming in have such highly specific areas of interest that they don't necessarily see that big picture of how it all fits together. And you know, I'm wondering where those people, particularly at universities are going to come from.
Dr. Rich Erdman (01:08:17):
The motivation and the incentive for them is definitely not to be generalists like Bill and myself. You tend to focus on one specific area. And so I worry a lot in that aspect.
Dr. Rich Erdman (01:08:47):
I'm thinking to myself, "Okay, who are going to be people that if we to replace Bill and myself, and most of the other people on the committee in those areas of expertise?" I can see some of them having a hard time, like in the mineral area. You know, that'd be a hard time, because there's not that many people working on it.
Scott Sorrell (01:09:19):
Gentlemen, this has been quite a joy. I've enjoyed every moment of it and wish we could kind of go on forever, but the alas, we cannot. We may need another round if we do that. What I'd like to ask each of you to do is just kind of give us two key points that at the audience can take away from our discussions this afternoon. And Rich, why don't we start with you since you've got the microphone?
Dr. Rich Erdman (01:09:43):
I think for me, I was talking about before, is that I have a lot more confidence. When I looked at them the mineral section, you know, and macro and electrolyte. I have more confidence that what we have is right. I'm not saying what we had before him was wrong, but in the end we're probably seeing about the same amount, but we kind of know why.
Dr. Rich Erdman (01:10:19):
I think we've done a much better job of, certainly on the macro side, on defining the requirements. So basically, it's more of a confirmation thing. What we were doing before that, you know, it was so accepted. It was pretty good. Maybe it was good for the wrong reasons, but it hasn't really changed much.
Dr. Rich Erdman (01:10:48):
And you know, if someone came to me and asked me, well, in the macros if you were gonna pick a macro element or some macro elements to work on, you know, what would I do?
Dr. Rich Erdman (01:11:01):
I could tell them, well this is where we have some holes. And we certainly have a lot less than we had 20 years ago. I guess one other thing I know we talked earlier about, whether it's the same with absorbed nutrient basis for the minerals.
Dr. Rich Erdman (01:11:28):
And I said, well we don't have good availability data, which is true. But we also talked about, this and you know what. Going back and just confidence in the diets would be backwards. And now I'm more convinced than ever that that would be a mistake. But we're on the right track, and we just need to keep on it.
Scott Sorrell (01:12:02):
Thank you, Rich. Clay, any final comments?
Dr. Clay Zimmerman (01:12:06):
Yeah, I thought the end of the discussion there about the gaps that are out there right now, I just really want to, to all the young scientists that are out there, grad students, maybe undergrads. You know, give some thought to that. That, you know, these are areas that where we need more research done. And I think back to when I was in graduate school and I asked one of my advisors. His graduate work was in the amino acid area, and I said, "Why did you, why did you stop working in that area?" He said, "Everybody was working in the amino acid area," at the time. So he took on a different specialty and became really became a world renowned expert in a little different topic area because of that.
Scott Sorrell (01:12:59):
Thanks for that Clay. Bill, we're going to let you put the bow on this.
Dr. Bill Weiss (01:13:05):
Well with minerals and vitamins. There's a lot, we still don't know. And so again, I'm going to plug the book. And we don't get a commission on this, in case you're wondering, or royalty. But we know a lot, but a lot of things we know we don't have enough. And so, you know, I really would encourage people to read the book, and I'm going to use magnesium as example. We know potassium antagonizes it, we had enough number, we've got an equation. But we also know fat can antagonize it, we just don't know how much. We know high RDP can antagonize, we just don't know how much. So if you read this, you start thinking, well, I've got these situations. I don't know exactly how much more I should feed, but I probably need to feed more. And on a lot of minerals, we went into stuff like that.
Dr. Bill Weiss (01:13:55):
So even though the software may not do anything about it, that doesn't mean we don't know anything about it, but the user has to read the book and make his own judgment. So it also points again to what Rich was saying, where one charge we did have from NRC was to include stuff on what is needed. So almost every chapter will have, may not be a specific section, but it'll say we couldn't do this; there's not enough data. We encourage research to study this area. So I, again, I don't just think of this as software. I think of this as a very good up-to-date reference material where you can tweak diets individually based on what's what's in the text.
Scott Sorrell (01:14:40):
Thank you Bill. I appreciate that. Rich, it's great seeing you again. Thank you for stopping by here at the Exchange. Clay, it's always good to see you. Gentlemen, this has been long awaited, but it was well worth the time, and it did not disappoint. I also want to thank our loyal listeners for stopping by yet, once again, here to the exchange to spend some time with us. And I'd like to remind our listeners that you can pre-Order a copy of the new NRC book and receive a 25% discount by visiting balchem.com/RealScience and click on the NRC series for a link and a discount code. If you like what you heard, please remember to drop us a five star rating on the way out. Don't forget to request your Real Science Exchange T-Shirt. You just need the like or subscribe to the Real Science Exchange and send us a screenshot along with your address and t-shirt size to anh.marketing@balchem.com. Our Real Science lecture series of webinars continues with the ruminant focus topics on the first Tuesday of every month. Visit Balchem.com/RealScience to see upcoming events and past topics. We hope to see you next time here to Real Science Exchange, where it's always happy hour, and you're always among friends.
[SS1]I listened to his previous podcasts but he didn’t drink anything that sounded like tuees. I found an Australian beer called Tooheys. Maybe that’s what he was referring to.
[SS2]What’s appropriated for …
[SS3]I thought it sounded like mineral loss fecal requirement
[SS4]Bill I think you were involved with one of those
[SS5]Casein
[SS6]I think this is right
[SS7]Previous studies
[SS8]The actual amount of total …
[SS9]Feed or a supplement
[SS10]Vary it accordingly