Confusion about NSC

[OceansAway]

Hi all,

I am trying to figure something out about NSC, yet I can’t seem to find exactly what I am looking for. What confuses me, is if the percentages are cumulative, and if so why is the emphasis so much on low NSC rather than amounts of feed being fed in total? Is the percentage per pound?

For example, (and I am completely making this up) if I am feeding a ration balancer with an 11% NSC, but fed LOTS of free-choice hay at 15% NSC, how is this any better than a horse that gets a higher NSC grain fed at several pounds, but fed less hay? Wouldn’t the horse eating lots of free-choice hay be consuming more NSC just by virtue of having free-choice hay, which would in theory be worse than the horse eating the higher NSC grain with be less hay, if one is trying to keep it low? Even if the hay is very low NSC? All I hear is more hay more hay, but wouldn’t that overload a horse just like too much grain, if fed at a high enough rate? I’m obviously ignoring that a higher forage-based diet is preferable, just to make this hypothetical situation.

If someone could enlightened me as to what’s going on, I would really appreciate it. Thanks!

[MorganMaresVT]

I think the short answer is that if you have a metabolically sensitive horse, you wouldn’t feed your horse hay with 15% NSC.

Groups like ECIR are now even saying that NSC isn’t the meaningful value, it’s ESC + starch values at 10% or under you should be targeting, across their full diet (which should be primarily forage).

Having a metabolic horse is a never ending trip down the rabbit hole of nutrition and chemistry.

Edited to add: This podcast features an interview with the ECIR folks talking about metabolically linked laminitis, and the last part of the podcast goes into some of the questions about diet, which values on a hay test to interpret, etc. https://thehumblehoof.libsyn.com/throwback-episode-managing-the-metabolic-horse

[OceansAway]

Thank you so much! I literally just made that number up with the 15% NSC so it had no bearing in reality! I don’t even know what averages numbers even are, for hay. It was just to set the stage, so to speak, for the example. I don’t have a metabolic horse at the moment, but rather just trying to educate myself, so I really appreciate your link.

You say the target should be 10% and under across the diet, but that still brings back my original question. What if the horse is a Hoover and consumes copious amounts of 10% forage, let’s say? Is that worse than a higher WSC + starch values but if the horse is eating much less of it?

[PaddockWood]

If we’re talking a metabolic horse with higher than normal insulin you also wouldn’t be feeding free choice. I know you know this but what we want is hay available 24/7… but trickle feeding.

Slow feeders. Hay nets. Whatever it takes to slow them down.

[OceansAway]

Yes, for a metabolic horse, for sure. More curious about how this is managed in one that is not metabolic, since I’d assume one still wouldn’t want that type of overload? Or one who is metabolic, and needs more calories, in which trickle feeding wouldn’t provide enough calories. I’d assume increase fat content somehow in the later case?

[JB]

Yes, absolutely, the total diet matters, BUT, you can’t just feed uber-low hay, which is such low quality that you have to also feed 6lb of a fortified feed per feeding that’s “only” 12% NSC, and assume that IR horse will be fine.

Yes, 2lb of a ration balancer at 15% NSC is likely - not guaranteed - to be ok for most IR horses, especially if it’s 2 1-lb meals, but it’s something to look at if the horse isn’t doing well despite appropriate forage

@MorganMaresVT

Groups like ECIR are now even saying that NSC isn’t the meaningful value, it’s W SC + starch values at 10% or under you should be targeting,

NSC is WSC + starch

It’s the ESC + starch that has become a bigger factor, < 10% but also with starch < 4%

That doesn’t mean ignore WSC, which encompasses ESC (ie ESC is a subset of WSC). I haven’t seen any cutoff number, but 13% WSC is likely just fine as long as the other 2 things (ESC+starch, and starch) meet the criteria.

@PaddockWood

If we’re talking a metabolic horse with higher than normal insulin you also wouldn’t be feeding free choice.

You can be. Katy Watts has talked quite a bit about how she can free-feed hay that’s low enough in all the right areas, to some horses who are confirmed IR, and I know of a few other friends who are able to do the same, once they’ve gotten hay that’s low enough, and especially once they got the whole iron/copper/zinc thing better managed.

@OceansAway

More curious about how this is managed in one that is not metabolic, since I’d assume one still wouldn’t want that type of overload?

There’s nothing out that that says non-metabolic horses MUST have NSC below a certain point. That said, “they” generally agree that 20% NSC (WSC + starch) is about tops of what you’d want to feed, in terms of feeds at 5-6-7lb+, because there IS some research that strongly points to longer-term diets that are “high” NSC leading to becoming insulin resistant, much like people consuming high sugar diets and type 2 diabetes. But even then, there’s workload to consider. The 100 mile endurance horse who trains for and does several 100 mile rides a year, and several 50-75 mile rides, or the upper level Eventer, can (and may even NEED) higher NSC feeds just to support the work. But they aren’t most horses, so you still have to consider that most horses aren’t worked nearly as hard as even their riders think, much less what the entirety of the nutritional requirements of horses are based on. So no, the horse who’s ridden 7 hours a week in normal w/t/c + discipline work, does not NEED 8lb of a 30% NSC feed. And, it may contribute to metabolic issues later. May. But he doesn’t NEED it, so don’t do it.

@OceansAway

Or one who is metabolic, and needs more calories, in which trickle feeding wouldn’t provide enough calories. I’d assume increase fat content somehow in the later case?

Feed as much of the low ESC + starch (without discounting WSC) hay as he needs, and then consider the concentrates. When you do need to consider concentrates, consider how many actual gm of sugar and starch (but starch especially because that’s converted 100% to glucose) he’s eating in a meal and in a day. Fat can be great, especially if they’re working on the harder side.

[PaddockWood]

These kinds of threads have such great value. Good point @JB on the importance of feeding enough copper and zinc and how it protects the horse in many ways including laminitis and allows other flexibility in the feeding program. We could say that right?

[Scribbler]

It’s like people. A diet that is just fine for a healthy person can be problematic for a diabetic or pre diabetic. A diet that’s fine for a working ranch horse or race horse can be problematic for a walk trot ammie horse. And some horses have long lean high metabolism race horse super model bodies and some are short and thick easy keepers. Like people. And some are fussy eaters and some are vacuum cleaners.

[JB]

@PaddockWood

the importance of feeding enough copper and zinc and how it protects the horse in many ways including laminitis and allows other flexibility in the feeding program. We could say that right?

I’m not really sure I understand your train of thought.

You couldn’t, for example, have a very tight fe:cu:zn ratio and therefore be able to feed the IR horse a hay that’s 10% starch and 8% ESC.

But if you’ve dialed in the wsc/esc/starch aspect, but the whole diet has a ratio of fe:cu:zn of, say, 40:1:8, which is out of whack in the cu:zn area which, contrary to popular belief, is the ONLY defined ratio of these minerals (fe:cu:zn:mn) at 1:3-4, then you may still have issues. Getting that ratio closer to at least 10:1:3-4:3-5 has definitely helped some IR horses, and an even smaller % seems to benefit only if the ratio gets closer to 4:1:3-4:3-5

[PaddockWood]

My thoughts didn’t make sense. Right, even if you’ve got your minerals right it only gets you so far. Could you dig a little deeper into what you’re saying with that last paragraph? The part about contrary to popular belief? I do have high iron on my hay and most every hay around here I’ve tested for 20 years has mostly been quite high.

[JB]

@PaddockWood

Could you dig a little deeper into what you’re saying with that last paragraph? The part about contrary to popular belief?

The NRC defines the amount of nutrients a horse needs, based on age/weight/workload (where workload can be actual work, or breeding). A 500kg (1100lb) horse in light work needs fe:cu:zn:mn in the amounts of 400:100:400:400mg respectively, as a minimum, and that’s really just to prevent disease.

Some groups, especially more lately it seems the cult followers of a very strict IR diet, seem to interpret that as the ratios of those things MUST BE 4:1:4:4. And there are other individuals who see those required amounts, and just assume it also means those are the ratios required.

But the ONLY ratio the NRC has defined is between cu and zn, which is around 1:4.

@PaddockWood

I do have high iron on my hay and most every hay around here I’ve tested for 20 years has mostly been quite high.

this is really common in the US. If you look at geological data that surveys soil, you can see that most soil in the US has a lot to a LOT of iron in it
Iron in Counties of the Conterminous States (usgs.gov)

It’s a little more complicated than this, there’s pH to consider, but in general, the simplified explanation is that the more iron there is in the soil, the more iron the grass takes up AND, the less copper and zinc the grass takes up. So Fe and cu/zn have an inverse relationship - higher Fe = lower cu/zn. There are a lot of grasses in the US that provide 3-4x the amount of Fe a horse needs, and not even half the Cu or Zn he needs.

[MorganMaresVT]

@JB

@MorganMaresVT

Groups like ECIR are now even saying that NSC isn’t the meaningful value, it’s W SC + starch values at 10% or under you should be targeting,

NSC is WSC + starch

It’s the ESC + starch that has become a bigger factor, < 10% but also with starch < 4%

That doesn’t mean ignore WSC, which encompasses ESC (ie ESC is a subset of WSC). I haven’t seen any cutoff number, but 13% WSC is likely just fine as long as the other 2 things (ESC+starch, and starch) meet the criteria.

I’m embarrassed to have mis-typed, but of course you’re right. ECIR recommends using the ESC + starch when interpreting your forage analysis. Thanks for catching that. I’m going to change in my first post so it doesn’t cause more confusion.

[JB]

No worries! In all fairness, there is a newer “movement” that I am seeing creep in to some of these conversations that “they” (not entirely sure who that means) are saying (again?) that WSC matters more, but I can never get an explanation. WSC can’t be ignored - I almost guarantee if ESC + starch is in line, but WSC is 20%, that IR horse will have problems. I don’t know if that’s what “they” really mean, but if so, it’s not coming across very well

[PaddockWood]

JB, could you answer a question. My hay this year came back at 274ppm on the iron which is 2241 mg at 18lbs fed. Does a level like that mean I need a professional consult?

[JB]

@PaddockWood

My hay this year came back at 274ppm on the iron which is 2241 mg at 18lbs fed. Does a level like that mean I need a professional consult?

Because of how high that is, I would assume a good bit of surface contamination. I would send another sample that you rinse first, dry, and submit, and see what you get. You can call them and see if they still have your sample and if they’re willing to do that. But I almost guarantee that’s a good bit of dirt, and iron from dirt is not very bioavailable.

[PaddockWood]

Thank you. Interesting - I’ve never heard of doing that. I’ll send in and report back.