Dr. Firkins’ presentation covers key aspects of how to improve digestibility of different diet components: fiber, starch, fat and total diet. (4:31)
This episode was recorded in Fort Wayne, Indiana, during the 2025 Tri-State Dairy Conference.
Dr. Firkins’ presentation covers key aspects of how to improve digestibility of different diet components: fiber, starch, fat and total diet. (4:31)
The negative relationship between starch in the diet and fiber digestion has been well known for more than 50 years. A recent meta-analysis showed the depression in fiber digestibility starts at very low starch concentrations. Dr. Weiss points out this can’t be due to low rumen pH at that starch level. Dr. Firkins agrees pH is probably only about half of the relationship and the other half is factors called the carbohydrate effect. He goes on to say adequate ammonia and amino acids are necessary for the fibrolytic bacteria in the rumen to maximize fiber digestibility, and urea alone is not adequate. The panel agrees there is little knowledge about what exactly the amino acid requirements of fibrolytic bacteria are or should be. (6:05)
Dr. Firkins shares some of his findings regarding how sugars impact fiber digestibility. Dr. Krogstad notes grain particle size can have key impacts on fiber digestibility and the panel discusses some of the challenges in nailing down optimal particle size. (13:39)
Dr. Weiss indicates diets should be formulated for rumen degradable starch - but how do we get that number? Dr. Firkins explains some of the difficulty in making accurate, cohesive predictions. The panel discusses some field measures that may be helpful. (18:24)
Ruminants have lower fat digestibility than monogastrics. The panel explores biological factors that might be limiting fat digestibility. Dr. Firkins believes palmitic and oleic acids probably help the microbes and that is why we see improved diet digestibility when those fatty acids are supplemented. He encourages further exploration into the reason behind this and the mechanism by which it occurs. Dr. Krogstad mentions a Utah State study that also saw improved diet digestibility and also evaluated microbial fractions and phospholipids. (22:44)
The panel explores the relationship between rumen-degradable protein and fiber digestibility. What happens when RDP is too high or too low? What is the optimal level of RDP to maximize digestibility? How does the composition of the base diet influence how much RDP you might need? What role do peptides play in the rumen? (29:00)
Panelists share their take-home thoughts. (41:52)
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Scott (00:07):
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 the latest ideas and trends in animal nutrition. We're here at the, uh, Tri-State Nutrition Conference, 2025, uh, in Fort Wayne, Indiana, and we are reviewing some presentations that's taking place this week. The one we're gonna review now is called Practical Steps to Improve Diet Digestibility, and that's done by Dr. Jeff Firkins from the Ohio State University. Jeff, welcome
Dr. Jeff Firkins (00:42):
Yeah, I think you did put enough.
Scott (00:44):
Well, uh, Jeff, before we get started, what I'd like you to do is just for the folks out there that may not know who you are, just kinda give us some background about who Jeff Kins is.
Dr. Jeff Firkins (00:53):
Okay. Uh, well, I'm originally from Illinois. Yeah. So I've met some people who are nearby where I'm from. Um, I went to the University of Illinois and did several degrees there, and then I've been at Ohio State since, uh, 19 87, 1 month, actually before Bill started there.
Scott (01:10):
Wow. Yeah. Excellent. But
Dr. Jeff Firkins (01:12):
He's older than me.
Scott (01:12):
Yeah.
Dr. Kirby Krogstad (01:16):
Well, my favorite game to play, and I'm just gonna do this now, is, uh, Jeff, what year did you start at Ohio State?
Dr. Jeff Firkins (01:22):
1987. And
Dr. Kirby Krogstad (01:23):
What year did you start? 88.
Dr. Jeff Firkins (01:24):
January of 88. One month. Different
Dr. Kirby Krogstad (01:26):
I, I just like to point out that I wasn't born until 1996
Scott (01:42):
So Kiring, while you've got the floor, why don't you tell the folks who you are? Yeah.
Dr. Kirby Krogstad (01:46):
Uh, my name's Kirby Krat and I've been on faculty at Ohio State now for, uh, just over a year. Um, before that I did research at Michigan State with Dr. Bradford and investigating, um, inflammation, animal health and nutrition, um, that I spent time at Nebraska before that with Dr. Conan off, and I'm a native South Dakotan, so I'm a jackrabbit
Scott (02:03):
Heart. Okay. Yep, yep. Yep. Good. Well, thanks for joining us once again. Thank you. Laura's gonna be my co-host today. Laura NIUs is, uh, a newly minted Balchem employee for AB from about six months ago. Right? Yep. Laura, introduce yourself to the audience. Yeah.
Dr. Laura Niehues (02:18):
Uh, my name's Laura NIUs, and like Scott said, I started with Alchem, uh, in December, so not too long ago. Uh, I've been getting caught up to speed and doing lots of podcasts. Uh, I've been in industry a few years, but prior to that I did my PhD at University of Illinois and looking at room protected amino acids during transition period. And prior to that I actually was equine nutrition for my master's at Kansas State University and resident of Florida. So always coming to the cold weather. Yeah.
Scott (02:47):
And so what do you do for biochem?
Dr. Laura Niehues (02:49):
I am technical services specialist at Balchem
Scott (02:51):
And covering what territory?
Dr. Laura Niehues (02:53):
Covering the East coast. So covering the whole east.
Scott (02:56):
Alright, good. And then Dr. Bill Weiss. Bill, thank you for joining us once again real quick. Uh, you
Dr. Bill Weiss (03:02):
Already know I worked
Scott (03:03):
For
Dr. Bill Weiss (03:05):
and I worked there for about 35 years. Retired a few years ago and getting better at golf and war on calf
Scott (03:13):
Very well, Jeff. Um, why don't you just kind of give us an overview of the presentation that you're gonna give tomorrow.
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Dr. Jeff Firkins (04:31):
Okay. Uh, so I'm, I was asked to talk about diet digestibility, so I'm gonna go through some key aspects of what is in the diet and how to try to improve them. Uh, so how, how we we can improve starch, digestibility a little bit. On the other hand, starch decreases fiber digestibility, some tips on trying to reduce that depression. I'm probably going to step out on a limb and talk a little bit about fat digestibility, which maybe I'll have Adam Locke correct me on
Scott (05:15):
Now, the one thing I liked about the, the title was his practical steps. So kinda give us an idea there. You're, you're gonna just kind of talk about, um, some things that nutritionists can do practically in the dairy. Dairy.
Dr. Jeff Firkins (05:27):
Well, I'm gonna try to, but my handicap is really high on that.
Dr. Jeff Firkins (05:31):
Worse than bills on golf,
Scott (05:33):
Is that right? Okay.
Dr. Jeff Firkins (05:35):
So, uh, I, I'll try to do that and give, give some examples the best I can. And, uh, you know, when I talk at these, I always try to provide the, the mechanism or something so that people can help to troubleshoot, not try to tell other people how to do their job better when, you know, they're doing that every day. So I'm gonna try to help 'em to think a little bit about what Yeah. You know, what kind of scenarios they might want to try.
Scott (06:00):
Yeah. Good. All right.
Dr. Bill Weiss (06:05):
I'll, I'll start off. You know, we've known this negative relationship when he starts in fiber digestion for forever 50 years or more mm-hmm
Dr. Jeff Firkins (06:25):
Yeah, I, I think, you know, the, the depression is probably only about half of it is pH, the other half is other factors that we call the carbohydrate effect. So it could be, I I never really looked up where those, you know, what kind of diets those were. Yeah. They could have been lower in protein or, you know, a lot of times, especially historically, people did, did things that are trying to set up, I'm comparing this to this and they don't really think about the rest of the diet so much. So it could be something like that. But I, but I feel like if we're, if we're gonna help to make sure we maximize fiber digestibility, we have to have enough ammonia and, um, amino acids, I'm gonna talk a little bit tomorrow that there's sort of a dogma that the lytic bacteria don't need amino acids, but there shouldn't be. It's they they do. And so we need to make sure we provide enough room degraded protein RDP. So, um, I think that's some of it. And some of it is they just displace the bacteria. They're just more, the more starch you give, the more or other bacteria of, you know, all swimming in the same swimming pool trying to find a place to, you know, to land. And so some of it's kind of that So
Scott (07:40):
Competitive exclusion, just pushing out
Dr. Jeff Firkins (07:42):
The a exclusion. Yeah.
Scott (07:43):
Right. Lytic bacteria are,
Dr. Bill Weiss (07:45):
Are, is highly digestible fiber more susceptible to starch depression than ba soy holes versus cornstalk.
Dr. Jeff Firkins (07:54):
Actually, that's a point I'm gonna make tomorrow that probably the, the source that is the most susceptible is soybean holes, or I didn't bring it up in there, but maybe something like corn, gluten feed, something that has a a, a really high extent of fiber digestibility. And we don't even think about it. We, you know, when we design these diets, we would try to lower starch, we add more soybean holes, and we improved fiber digestibility. Yes, we did, but we, we lost some fiber digestibility because we, we didn't get all that we could have out of those highly degradable soil holes. So it doesn't mean you still don't have a negative effect. So Yeah, I think they're even more prone. Exactly.
Dr. Kirby Krogstad (08:37):
I wanna dovetail on the interaction of the starch and fiber a little bit because it's, it could, if I remember right from a paper, I think it was a Hoover paper in the eighties, looked at Hein, got NDF digestion versus ruminal digestion. And so like the depression effect of additional starch, is that just ruminal? And if it is just ruminal, then you would expect a ruminal degradable starch to depress that more so. And is that data out there, does that, has that relationship borne out?
Dr. Jeff Firkins (09:03):
Uh, wow, that's, I I think you're probably right that if we, if we have really high starch and we depress fiber adjustability in the rumen, we probably are also are in the large intestine. But boy, that's hardly ever been looked at. Yeah. Especially for dairy cattle. Uh, placing an IAL cannula in dairy cattle is really hard. I, I did that for a few studies and I got tired of being called out in three in the morning
Dr. Jeff Firkins (09:30):
So, uh, so it's really hard to to know, but I, I think there probably is some of that, you know, the, the more cow eats, the faster the passage rate that affects the rumen, but it also affects the hind gut too. So there's only so much time that, that that's there. And the more you prolong the, the negative effects downstream, the less time you have to get proper fiber digestibility. Right. And, and in sheep for example, it's probably the opposite. They have a longer, large intestine. There probably is more opportunity for compensatory fiber digestibility, but that's just a guess, but yeah. Yeah, it hasn't really been done.
Dr. Bill Weiss (10:10):
Do you think, you know, there's old data again showing high protein diets well in excess of requirement improves dry matter digestibility significantly is do you think you'd see the same thing with urea? I get that question a lot is, can, can I feed urea, meet the RDP requirement and still get all the benefits of say, so A RDP or some other RDP source?
Dr. Jeff Firkins (10:35):
I really don't think you can. Uh, you could, if, if you really are suffering from a ru ammonia deficiency and then yeah, then urea is a good way to go. But the, like I was just saying at the beginning, you know, the lytics, they don't just need ammonia. I know they're sort of the dogma that they do, but they need actually amino nitrogen, probably not just the branch chain ones, but also probably pheno alanine and, uh, weirdly, maybe even proline. It's kind of, uh, potentially limiting one. So I, I think they need to have natural RDP, not just that, not just u okay,
Dr. Laura Niehues (11:16):
What is our knowledge on what those requirements would be then if we're looking at, say just looking at branch chain amino acids and if you mentioned phenyl alanine, how, how comfortable are we with saying, okay, we probably need this much for the rumen in addition to what we're thinking about for what we want the cow to receive.
Dr. Jeff Firkins (11:36):
It's little bit of the wild west that we, we kind of don't know. So, you know, we draw from in vitro kind of studies that to try to extend it to what is needed in the cow. But, uh, you know, to a certain extent it's really hard to do because they mix up the amino acids, they break down and provide mixed carbon skeletons and then they make what they want out of it. So you can't just feed, uh, let's say lysine and see does that improve digestibility or does it improve microbial protein? So you kind of have to look at them in a combination. And that really hasn't been done. But I, I think it should be, I think there really is a need for at least some of them could be that methionine could be limiting in some cases, believe it or not. Um, in the rumen you mean?
Dr. Jeff Firkins (12:25):
In the rumen? Yeah. And, uh, so, and, and it probably depends on the microbes that are there and so on. Like methionine is something that when people study fiber degradation and use pure cultures of lytics, they always put a little bit of methionine in
Dr. Bill Weiss (13:26):
What about sugar? You've done, uh, you've worked on sugar almost your whole career at OSU over time. So is it better than starch with respect to digest total diet digestibility?
Dr. Jeff Firkins (13:39):
So I'm, I'm actually talking about that a little bit tomorrow. Um, you know, there are some studies that show that sugar improves fiber digestibility, and you have to ask why. And I, I actually went back to some of the sources, uh, on that. And uh, I think some of it is that probably sucrose, believe it or not, can be used and possibly could help some of the lytics. So it could be that it really does work in a way like that. But part of the aspect that I'm gonna talk about tomorrow when we say sugar, a lot of times we're adding like molasses mm-hmm
Scott (14:24):
Doesn't matter what kind of sugar, glucose, sucrose. Fructose.
Dr. Jeff Firkins (14:28):
So people have actually done some of that fructose. There's a few studies with sucrose where they've added it and improves fiber digestibility. Uh, it could be that it's the fructose part of it, so I wouldn't be surprised about that. I think it's probably not just glucose or maltose, they, those seem to stimulate the, the amlo, the ones that break down, uh, starch, the alytics. So I think, uh, probably the sucrose one, um, could be lactose. I get asked about lactose a lot. Mm-hmm
Dr. Kirby Krogstad (15:07):
Before we get away from the carbohydrate discussion, I had a question about at least one of the most practical things I can think of when I talk to farmers and nutritionists is, is corn particle size, grain particle size? What, um, you know, what do you think that particle size needs to be in a diet and, 'cause I think we're in a trend of smaller is better, smaller is better. Um, and is that the case or is there a floor to that number we should be shooting for? Or, you know, what, what do you think?
Dr. Jeff Firkins (15:31):
So I, I've always, I won't say always, but for a long time have been thinking, well, we might as well get the most we can out of it. Mm-hmm
Dr. Kirby Krogstad (16:04):
I think I know what you're hinting at
Dr. Jeff Firkins (16:05):
Scott (16:37):
Kind of building on what Kirby was asking, is there any benefit to maybe having multiple, uh, sizes of, of, of, you know, you got your finely ground corn, maybe some medium ground so that it kind of, uh, levels out the availability of the starts in the rumen?
Dr. Jeff Firkins (16:53):
Uh, yeah. You, you can't, uh, that would be a good thing to do if we could project what the d the overall digestibility would be. But the more variation you have like that, I think it's harder to guess it. Got it. Like if you have the more vitreous kind, if you've, you know, grind it really finely, you can take away the vitreous of it. And so if you had more moderate particle size of a flowery kind of hybrid, then probably would do pretty well. So, um, I, I don't know. I, I, I sort of feel like we want to grind finer, but we don't want to have a bunch of dust either. Mm-hmm. So,
Dr. Kirby Krogstad (17:31):
I mean, we have particle sizes out there now and sub four 50, sub 400 micron in some cases. I mean, there's some, some pretty dusty corn getting fed to dairy cows out
Dr. Jeff Firkins (17:40):
There. Yeah. I don't think we want, you know, something like that that could be unpalatable. But, um, you know, like, like I, I always kind of thought like in, you know, you think about we send all this corn to California and then they steam flake it all mm-hmm
Dr. Kirby Krogstad (18:15):
I, I, I think I would agree. I, I know Nassim has a discussion in there about grain particle size and grain source on the fiber digestibility depression. And I think it's a question we have yet to address.
Dr. Bill Weiss (18:24):
So you, I think everybody would agree we should formulate for rumen, fer, animal starch. How do I get that number?
Dr. Jeff Firkins (18:32):
Yeah, that's, I actually did a study where I did formulate that and it seemed to kind of work a a along what I had projected, but where do you get the numbers for that? That's, that's a tough one. Um, it's as, as, as you know, I've kind of been talking about like doing duodenal cannulation versus like now everybody do a nasal sampling through the rumen cannula. You kind of get different numbers for starch and that's kind of making it really hard to come up with here's what this ru degraded starch value is. 'cause it depends on which system you use and we don't know which one's. Right. So, uh, ideally we would do that. If, if we could come up with cohesive values for that, um, then it would be ideal. I don't have a good way to do it. So many people feed corn and they don't measure the particle size like you're obviously doing now, Kirby mm-hmm
Dr. Jeff Firkins (19:59):
It's not hard. We should be doing it then, then the meta-analysis will come out good. Like in Nasim, we had a really hard time trying to predict, um, room and starch digestibility because there was so many imbalance studies. Uh, you know, like, like I still remember this, you know, doing this work. And it kept saying that barley starch digestibility was lower than corn. Yeah. And of course, we all know that can't be. Right. And, and I went and looked at, and because the studies where barley was added, like one of the stu studies barley was added to a diet that had corn silage in it that was 49% dry matter. What do you think the star digestibility of that corn silage was? So it brought everything down. Then it makes it, when you're looking at barley versus corn, it's like barley's low. I mean, it's like, it's just really hard to do that stuff. So, uh, but ideally, bill, if I could do that, if one thing that I would do if I had, you know, my magic wand, I would, I would do that. I would come up with a cohesive way to say, this is a good estimated room. Integrated starch.
Dr. Bill Weiss (21:04):
Yeah. There's some labs that measure it differently, but they give something called room and availability or different names. But does that have any, has anybody looked at, does that lab value have any relationship to what you're trying to formulate
Dr. Jeff Firkins (21:18):
For? Yeah, so, you know, I've, I've been in, uh, I've talked like with Mike Allen a lot about that. Of course, he's retired now. Um, and the, the lab values, they definitely rank, you know, so if somebody is looking at a diet and then they send off the starch sample and it says, here's the seven hour digestibility. If it's higher, we know it's higher if it's lowered slower, but it, it's more of a ranking tool. We know doing that in vitro is really, it's, you know, really tricky research to do. You overwhelm the system. It's not even, you can maybe manage pH in it, but the microbes, they take, they break down the starch, and then what do they do? They turn it into like this extracellular stuff that measures this starch
Dr. Bill Weiss (22:17):
It gets us part of the way there.
Dr. Jeff Firkins (22:19):
It gets us part of the way there. And it's better than not doing it. Fecal starch, same thing. I I, I, I feel like if you get more digestibility in the room and you're gonna get more digestibility in the total tract and less fecal starch. So it's a good, it's a good ranking and, uh, troubleshooting guide. If I were in the field, I would, I would definitely be doing that.
Dr. Bill Weiss (22:44):
I'm gonna switch gears to fat. You know, ent, fat naso says it's average about 75%, give or take a little bit, which for all species that's really, really low. What is it, is it analytical issues to, you know, is it the digestibility apparent versus true? Or is it something biologically limiting fat digestibility in, in ruminants?
Dr. Jeff Firkins (23:10):
I, I think there is something limiting biological fat digestibility, no doubt. Um, you know, pancreatic lipase is going to be less because the rumen microbes just, you know, chop off all the fatty acids. Why would they need it evolutionarily? Why would they need it? Unlike a pig that has all kinds of it. Uh, and, but some of it's beyond that, like the, the, the typical ways that work with lipase, you know, and, and cell formation. We've kind of reduced those. So like, um, phospholipids that are in the, in the diet, some of them can help to emulsify fat in the intestine and the microbes break them up a monoglyceride, like a, a pig eats a triglyceride. It, it retains a monoglyceride that helps as a detergent to emulsify. So one, one of the things that I think is I've sort of, uh, projected is that probably part of the microbes cell walls is they're being broken down.
Dr. Jeff Firkins (24:13):
They probably help to emulsify the fat. They help the animal to, to improve fat digestibility. And so, um, I think no doubt there's kind of a limit. You start feeding too much fat and that limit's way lower than in, well, unfortunately for us
Dr. Jeff Firkins (25:10):
And it's, you know, we can, we can get more energy in that way. Um, I'm gonna talk tomorrow a little bit about why I think some of the, some of the fatty acids, PME and oleic probably help the microbes. They probably can take them up and potentially even improve fiber digestibility. So Adams and his group have been talking about it. Mm-hmm
Dr. Kirby Krogstad (25:48):
And there's actually some neat data out of, uh, I think it was University of Utah or u sorry, Utah State University had an in vitro study looking at palmitic acid. And, and it also bumped digestibility pretty clearly. And they were looking at some microbial fractions and, and microbial phospholipids. I think it was a neat data set that echoed a lot of what Dr. Locke has seen.
Dr. Jeff Firkins (26:06):
Yeah. There's, um, I'm, I'm gonna go through a study tomorrow from Florida, but there's others. Ben Winter has done a study, um, that's, that shows the same thing. It's, it's pretty consistent.
Scott (26:18):
Any thoughts on how much you should supply to the rumen as opposed to bypassing the rumen?
Dr. Jeff Firkins (26:23):
Well, you know, the thing with palmitic acid, a bunch of it does kind of bypass, but it's more soluble than, than steric acid 18. Oh. So enough of it kind of like bumps into the microbes and they probably are able to sort of add, absorb it, then it kind of like moves through their membrane and then they can, then they can use it. So pro, um, you know, I'm gonna say tomorrow probably you've heard that
Scott (27:07):
Interesting.
Dr. Jeff Firkins (27:07):
So, you know, one and a half, 2% of that kind of fat is probably has a potential to improve fiber digestibility.
Dr. Bill Weiss (27:17):
I, I know when I was in school taking lipids from Dr. Palmquist, it was everything was fat was negative on NDF and it was different fats back then. But I can remember lecture after lecture on how you have to incorporate the depression and fiber digestion when you're doing the economics on fat supplementation.
Dr. Jeff Firkins (27:36):
Do you know, that's really interesting you bring that up. 'cause remember in, you know, in nas we kept talking about it and, and like, you know, Lou Armano was, was bringing up, well, you know, a lot of those studies, they fed a lot of fat 'cause they were trying to prove something. That's what we do. And we design studies, we wanna see a significant difference. So we put a bunch in. But when you do kind of a moderate amount, it usually doesn't depress fiber digestibility. And before, before you start depressing fiber digestibility, you're probably going to, you know, do something to milk fat or whatever first. Mm-hmm
Dr. Laura Niehues (28:19):
Now, has that improvement in fiber digestibility with very specific fat feeding, has that been seen in vivo or is that mostly in vitro work then?
Dr. Jeff Firkins (28:29):
Um, both. Both. Um, like I don't know how many studies Adam has, uh, more than five. Unless maybe not 10, but he's got a lot of studies repeatedly. Pul acid blends, improve fiber digestibility.
Dr. Kirby Krogstad (28:45):
Yeah. Pretty stable. Two or three points. I think two is
Dr. Jeff Firkins (28:47):
About, yeah. Two, two or three points. Yep. That's about right.
Scott (28:49):
Is there an advantage supplying that in the, uh, fatty acid form as opposed to triglyceride free fatty acids?
Dr. Jeff Firkins (28:54):
Free fatty acids? Yeah. Know that's, I think that's what you want. Yeah.
Dr. Bill Weiss (29:00):
In, in your paper you talk about excess, excess RDP being negative or potentially negative on fiber digestion, which I thought was interesting. What, what do you think the mode of action of that, of excess
Dr. Jeff Firkins (29:15):
Of, of course excess is a lot. Yeah. You know, like 20, uh, something like that. It's
Dr. Bill Weiss (29:20):
Not practical, but still
Dr. Jeff Firkins (29:20):
It's not practical.
Dr. Bill Weiss (29:21):
But why would that happen?
Dr. Jeff Firkins (29:23):
Uh, that's a really good question that, uh, I want to ask your former grad student who, who actually did that?
Dr. Laura Niehues (30:34):
We know that we need some amount more of RDP going in as we improve star digestibility. That, that's kind of, um, something that you've established a bit too. So can we just classify that as RDP? Do we, and you've talked a little bit about the amino acids, and we obviously don't know the requirement there, but if we just say, say 10% RDP is where we wanna focus, or 9% RDP, is that getting us by enough to keep fiber digestibility where we want it and coordinate with the starch? Or kind of what are your thoughts on
Dr. Jeff Firkins (31:13):
Um, uh, it another thing that I, I think you hit right on the nail, right on the head. We need to have adequate RDP for sure. And if you know, 10%, maybe potentially more if, if we have really highly degradable dyes, really good quality feed stuffs, and then if we could, we would start looking at the kinds of degradable amino acids within there. And you know, like, like all the systems, they assume every amino acid is degraded at the same rate. And of course they're not, uh, probably the branch chain amino acids are degraded at a, you know, maybe a little bit different rate and so on like that. So, uh, that probably is exactly right. I think, I think pheno alanine is, is a premium one for fiber degraders over and over the in vitro studies show it, but it hasn't been done in vivo.
Dr. Jeff Firkins (32:06):
So we don't really know. But I, I think we'll be moving toward that if, you know, if we can get systems to be able to, to do that. I, I feel like we need to do amino acids. Nobody does amino acids in their studies anymore.
Dr. Bill Weiss (32:59):
You know, there, we've talked about this over a lot a long time. There's studies showing, again, very high RDP 12, 13% and the well above requirement intake keeps going up. Is this, do you think a, a digestibility thing or is it something, something else?
Dr. Jeff Firkins (33:17):
It's more, um, some of it is related to fiber digestibility and, and reducing the fill limitation. So like that you're talking about there, the digest more, the cow can eat more because it's got more room in the rumen. Ru in the rumen. That's a good one.
Dr. Kirby Krogstad (33:36):
Uh, trademark Firkins
Dr. Jeff Firkins (33:38):
Dr. Jeff Firkins (33:42):
So, so some of it's that, but you know, in other, in other animals, they find the same thing. I, I had this conversation with Chris Reynolds 20 years ago when he was at OSU. They did a study one time where they infused ammonia into the, into the blood and, and it, and it increased intake
Dr. Jeff Firkins (34:32):
There, there could be some way they're sensing that. So yeah, I think, I think that's on the flip side of that bill, if we start not having enough, we probably are more likely to limit feed intake, maybe not just because of what's happening in the room. And, and then as you brought up, especially as we have more room integrated carbohydrate, there's more energy for microbes to grow. They need more RDP mm-hmm
Dr. Kirby Krogstad (35:24):
I had a question on the RDP kind of a ration balancing hypothetical. You know, a lot of the research that gets done in dairy nutrition is done in the upper Midwest and the Northeast where we're feeding diets that are 18 to 24 forage NDF. Um, and I've gotten to know a few nutritionists out west, you know, they're oftentimes feeding diets with 20 30% forage, 10 to 12 to 15% forage NDF you know, that are gonna be rapidly passing through the rumen. Do you think that changes the percent dietary RDP that they should be targeting, um, that maybe, you know, would make that more optimal?
Dr. Jeff Firkins (35:59):
Oh, that's a good question Kirby. Um, you know, I don't really have experience to to, to go along with this, so I'll just speculate and you can decide if you wanna keep
Dr. Kirby Krogstad (36:07):
That's a podcast for four
Dr. Jeff Firkins (36:09):
Yeah, there you go. Uh, I, I think probably the more adjustable things are the, uh, the, the, probably the more RDP you need to have. The thing I have talked with people about in the West that you didn't mention, there's a lot of BLE fiber mm-hmm
Dr. Kirby Krogstad (37:15):
Yeah.
Dr. Jeff Firkins (37:16):
And of course, you know, the, the flip side is when you have a lot of highly degradable forage, you need to have enough room and, uh, compaction mm-hmm
Dr. Kirby Krogstad (37:31):
Right.
Scott (37:34):
Any other key points that, uh, you plan to cover tomorrow?
Dr. Jeff Firkins (37:38):
Uh,
Scott (37:56):
Yeah.
Dr. Kirby Krogstad (37:57):
Well, I, I did wanna ask one more question. Uh, your student brought it up yesterday in their presentation about peptides and, and the role of peptides in the room. And, and I I was kind of just wondering if you could expand on that a little bit. 'cause it's a story I think needs developing.
Dr. Jeff Firkins (38:10):
Okay. Uh, you know, so peptides are, first of all, um, you love 'em and you hate 'em. There's no good way to measure 'em. Mm-hmm
Dr. Jeff Firkins (39:01):
The cytolytic don't do that very well. They have proteases that they need for their own internal functions, but they don't break down feed protein very well. And so they rely on other bacteria to do that in protozoa, and then they feed them ammonia and the other stuff that they need. Well, the, the bacteria that break down, uh, protein mostly are like starch users. And so what's, what's encapsulating starch granules protein, they have to have proteases to get what they want, but they don't have, they don't have to have all the peptidase to break down the protein that's been partially broken down. They don't, they don't need peptidase unless inside their, their, their cell is telling them they need more amino acids. Go get some go upregulate, peptidase. Mm-hmm
Dr. Jeff Firkins (40:01):
You put some protein in RDP is the same no matter what kind of diet. Well, it probably isn't. And so, you know, we know that there's some soluble protein that passes the rumen. It's probably all peptides. It's not the actual protein so much, it's the peptides. And then, uh, so we're, we're kind of looking at as, uh, what kind of situation would help them to be broken down more? And they, it does seem to be interacting with the branch name VFA concentration. So, uh, that's what she presented. So I think we need to go back and, you know, this work hasn't been done since the eighties and nineties when you guys were talking about when you
Scott (40:42):
Were born.
Dr. Jeff Firkins (40:44):
But, uh, but they did some great work back then. And then molecular biology, you know, came into play and it was a whole lot easier to do that. So I think peptides are, are gonna be a part of the future and, and dairy nutrition research. So I don't, you know, without going into a bunch of science there, I think it's, it is really exciting. We should be doing it more.
Scott (41:08):
Got a lot to look forward to Kirby? I think so.
Speaker 6 (41:26):
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Dr. Laura Niehues (41:52):
I, I think for me, the biggest key takeaway is thinking more about that RDP and amino acid requirement that we have for the rumen, and to really start incorporating that in and taking into account the amount of fermentable star and how as we improve the amount of fermentable starch that we need to think about the fact that we're going to have a larger demand for RDP and specific amino acids. So I think just keeping that in mind, especially as we formulate for specific amino acid requirements of the cow herself, that we need to not forget about the rumen as we're doing that.
Dr. Jeff Firkins (42:30):
Yeah, that's, that's a really good point. And I would say not just rumen fermentable starch, but soluble fiber and really highly degradable fiber, like that's with really good forages. Um, I still kind of come back that the cow valves, you know, to break down fiber
Dr. Kirby Krogstad (43:21):
I think before I'd give my final take home, I, I wanted to point out, I was like, this is the great part about having someone who's new to the Buckeye family and getting a chance to work in this place. The, the chance to work with the likes of Dr. Firkin to get to know Dr. Weiss is like just cat that free young scientist who try to absorb as much as you can. So I want to thank both of you guys for mentoring me along as I've transitioned into this role. But my takeaway is something, um, I've heard both of these guys say is that it's diet formulation is, is not just putting something in, you're also taking something out. So you gotta take that whole picture into consideration. It's, it's not taking out starch put and, uh, or just adding starch. It's taking out soy holes or it's taking out little fat, or it's putting in a little forage fiber. You know, it's a, it's a calculus that we have yet to really understand. Mm.
Scott (44:04):
Great comments. Bill.
Dr. Kirby Krogstad (44:06):
Uh,
Dr. Bill Weiss (44:06):
I think, you know, we need to remember the limiting nutrient for milk is still energy. That's still, and it's been that way forever. And so these little changes, that one or 2% change increase in digestibility is, is huge. Yeah. And we, we forget that, you know, it, it's, and so all this emphasis and all these little details that matter, they matter even though the, the, the actual change in digestible or digestible energy might be small, but that's, if it's the limiting nutrient, you will get a response.
Scott (44:37):
So, yeah. Yeah.
Dr. Jeff Firkins (44:40):
Again, it comes down to fiber to me. Yeah. You know, we've done a lot to improve digestibility of everything else. Yeah. We talked about fat, we've improved that digestibility, corn fiber. Even, even now it seems like we add 1% more starch, we take away a quarter of that that we give back because we're losing fiber and digestibility. Do we really want to do that? We should be able to find a way to limit that, that we give back that winds up, you know, in the manure pit and makes methane or whatever. We, we should be able to improve it because we can. And then try to get cows to eat more and have a, just a little bit better diet along the way. So, yeah, that's, uh, that's why I'm gonna try to hit, hit home tomorrow.
Scott (45:29):
Yeah. Good, good. Looking forward to it. So I think that's a great stopping point. Uh, Jeff, this has been enlightening and it's been a lot of fun. So I want to thank everybody for joining in on that. This has been good. Laura, thanks for joining us here as, uh, as the co-host. You do a great job. Thank you, Scott. Even though you guys are so young, you guys do a great job. But
Speaker 6 (46:07):
We'd love to hear your comments or ideas for topics and guests. So please reach out via email@anh.marketing at balchem.com with any suggestions, and we'll work hard to add them to the schedule. Don't forget to leave a five star rating on your way out. You can request your Real Science Exchange t-shirt in just a few easy steps, just like or subscribe to the Real Science Exchange. And send us a screenshot along with your address and t-shirt size to anh.marketing at balchem.com. Balchem's real science lecture series of webinars takes place on the first Tuesday of every month with the top research and nutrition topics that will impact your business. We also include small ruminant, monogastric, and companion animal focused topics throughout the year. Visit balchem.com/realscience to see the upcoming topics and to register for future webinars. You can also access past webinars and search for the topics most important to you.