I’m with you here. I still am not seeing enough math to follow how this works to show that it is the minerals in the hay part of the diet that are being absorbed better.
It’s always a good idea to question research which draws conclusions that are very new and/or different from long established norms! The good news is that there’s a well established, scientific peer review system to help with this. Now, a few points about the “study results” that are being so thoroughly scrutinized here:
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This is indeed an ABSTRACT from data that was presented at last year’s Equine Science Society meeting. Abstracts such as this are submitted for limited peer review, and accepted or not for presentation at the meeting. The study may not have even been entirely complete at the time the abstract was submitted, as is common with abstracts submitted for scientific meetings.
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Often, scientific meeting abstracts only provide limited information from a much larger, more thorough study that is ongoing or nearly complete. Thus, they should usually be regarded as partial/pilot data, and NOT complete studies. That’s why its missing some “key” data, such as the specific type of hay. That doesn’t mean the authors don’t know what type of hay it was, and it’s complete nutrient analysis - or that it won’t be reported later in a more comprehensive, thoroughly peer reviewed published manuscript.
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There’s not a lot that can be definitively concluded from this abstract, or any such type of abstract. The authors know this. They are not trying to make definitive claims here. Frequently a meeting abstract is followed up by a full manuscript in a peer reviewed journal anywhere from months to years later. Wait for it, these things take time. Certainly there will be much more detail to support any actual conclusions that are (or are not) made.
Indeed, funding source should always be taken into consideration when interpreting a study. However, it’s also well worth noting the long history of Waltham’s support of academic equine research. I have no affiliation with them, but have had interactions in the past. FWIW, they did not direct me to do a specific type of study or investigate a product, but rather they inquired about the topic I was interested in - and if my study design would meet their rigorous scientific and welfare standards. Just my experience, not claiming that they or any other feed company are actually perfect. We now know a lot about equine physiology thanks to support from Waltham, and note how many of these studies have nothing to do with selling a product.
https://www.ncbi.nlm.nih.gov/pubmed/…thor%5D+equine
And in fact, many of those “respectable studies” have actually been conducted by some of these very same authors Rest assured that these are not a bunch of amateur shrills. As noted above, wait for the full manuscript to be added to their extensive list before jumping to serious conclusions
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This is really interesting to me. I have an 18 y/o gelding that has lost a bit of topline in the past year. He is currently on a vitamin/mineral supplement, beet pulp, and a handful of alfalfa pellets. Hay is Coastal (Orchard gives him the runs and Timothy is almost impossible to source here). Overall he looks very good, it I do wonder if perhaps he needs a protein boost, especially since Coastal hay isn’t the best for protein content.
I’m I’m thinking of dumping the vitamin/mineral mix and going back to a ration balancer. Thoughts? I can’t decide if his topline loss is just age related or maybe a protein deficiency.
Coastal hay is typically not a good hay for more challenging horses. Even good Coastal is sort of just ok, compared to many other hays. No doubt it’s not enough protein for him, and what you’re supplementing now isn’t providing any of significance. So yes, at least a balancer.
That’s exactly what I was worried about. Thanks JB!
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I’ve read the abstract and the Horsetalk article several more times now… The quote from Clare Barfoot in the Horsetalk article does seem to be saying #2 above. It’s quite possible that he/she has additional information, and that it is true that the digestibility of the nutrients in hay increases when fed with a fortified feed, but I don’t see that in the abstract.
Is there something I’m missing? There is nothing about digestibility of forage being improved by addition of concentrate.
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It is very possible that the hay + carb-rich concentrate diet had lower NDF intake because it just has lower NDF than the hay only diet and the hay + fiber-rich concentrate diet. We don’t know how much hay or concentrate any of the horses on any of the diets were offered, and how much of it they ate. We don’t know if the overall intake of the hay + carb diet was less.
From the abstract: “Notably, the CHO diet had a lower NDF intake and digestibility compared with the FF and HAY diets (P < 0.01), although none of the diets differed for percent NDF digested (P = 0.14). Gross energy did not differ between diets for intake (P = 0.20), however diets were different for fecal energy (P = 0.03), apparent digestible energy (P = 0.02), and percent apparent digestible energy (P = 0.01). The HAY diet was lower than the other 2 diets for fat intake, amount digested, and percent apparent digestibility (P < 0.01).” (italics mine)
None of the diets differed for percent NDF digested. The HAY diet was lower than the other 2 diets for percent apparent digestibility… but that could be because it was only hay. The other 2 diets could have higher apparent digestibility because the concentrate portion of the diet has higher apparent digestibility, bringing the TOTAL apparent digestibility up.
Made up #s for illustration:
Hay digestibility: 50%
Hay + concentrate digestibility: 60%
The higher # for the hay + concentrate digestibility could be because hay digestibility increased, and because concentrate digestibility is higher… ie: averaging 55% hay digestibility + 65% concentrate digestibility = 60% TOTAL digestibility.
OR it could just be because the concentrate digestibility is higher… ie: averaging 50% hay digestibility + 70% concentrate digestibility = 60% TOTAL digestibility.
But we have no way of knowing at this point, because the abstract does not say.
The abstract does say, as its conclusion: “However, the HAY diet consistently had lower macro and micronutrient digestibility compared with the other 2 diets. The CHO and FF diets were typically not different. These data suggest that non-working horses may require supplementation if on a hay-only diet and provides support that moderate fat diets do not appear to have a negative effect on mineral digestibility.”
Nothing at all about addition of concentrate improving the digestibility of forage, though.
Yes, there is 
You stated it as well.
In the JEVS link, it specifically states
“However the HAY diet consistently had lower macro and micronutrient digestibility compared with the other 2 diets”.
If apparent digestibility of nutrients goes up when fed concentrates, in addition to hay, then digestibility is improved
OVERALL digestibility of nutrients is improved. But it does not necessarily mean that adding a concentrate improved the digestibility of the forage. The higher digestibility could be because the digestibility of nutrients in the concentrates is better.
I think most telling is the final sentence of the abstract: “These data suggest that non-working horses may require supplementation if on a hay-only diet.”
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