Re-Engineering Calcium Delivery for Variable Fresh-Food Diets: A Low-Phosphorus Calcium Architecture for Canine and Feline Nutritional Balancers

Manuscript 1 of 8 in the BARC Protocol specification series · Release B-2.1.0 · September 2026

Author. Prasanna M, Growlrr Foods Pvt Ltd, Chennai, India. Correspondence: support@growlrr.com. ORCID: 0009-0003-6812-347X.

DOI. 10.5281/zenodo.22647608 — the concept DOI, which always resolves to the current version of this record · Published. 8 September 2026 · Licence. CC BY-SA 4.0 · Status. Not peer-reviewed as of the date of publication, 8 September 2026.

Competing interests and funding. The author is the founder of Growlrr Foods Pvt Ltd, a pioneer and proponent of the BARC Protocol for pet foods. BARC stands for Biologically Appropriate, Residually Corrected, and is conceptualised as an open protocol under a Creative Commons Attribution–ShareAlike licence, for like-minded collaborators around the world to formulate and develop. Growlrr Foods Pvt Ltd develops and commercialises a BARC-based residual-correction product, BowlBalancer. The work was funded entirely by the company; no external funding was received. No independent laboratory, institution or reviewer has verified the results reported here. Readers should weigh these facts alongside the analysis, which is published in full — including its limitations and open items — precisely so that it can be checked.

Framework. This work applies BARC — Biologically Appropriate, Residually Corrected — an open protocol for correcting a biologically appropriate fresh base to a published nutrient standard, released under a Creative Commons Attribution–ShareAlike licence (CC BY-SA 4.0) at growlrr.com/barc-protocol (concept DOI 10.5281/zenodo.22648597) so that others may formulate and develop against it. BARC is the protocol; the correction specified and validated here is one implementation of it.

Terms. A glossary of the statistical and nutrition vocabulary used across this series — requirement, floor, safe upper limit, Wilson bound, N-limited, draw, stress multiplier, retention factor, trituration and the rest — is in the series cover note (10.5281/zenodo.22647606), section 4.1.

Computational tooling and AI assistance. The model is implemented in TypeScript under Node.js with no external numerical dependencies. Claude (Anthropic) was used as a coding and analysis assistant in developing this work and preparing these records; it was not used to generate results, all of which were produced by executing the model. See the series cover note (10.5281/zenodo.22647606), section 6.1.

Plain-language material. A non-technical account of calcium in home-prepared bowls is at growlrr.com/pet-home-cooked-recipes-blog/calcium-for-dogs. The public reference list behind these claims is at growlrr.com/pet-nutrition-references.

Provenance of the numbers. The architecture described here was introduced at release B-2.0.0 (22 August 2026) and is unchanged in B-2.1.0, which altered only the random-number seeding of the validation engine. Figures are quoted with the release that produced them.

Abstract

This paper presents the material-science rationale, structural mechanics and mass-balance outcomes of a re-engineering of the calcium delivery system used in a precision micronutrient corrector for home-prepared cat and dog diets.

Micronutrient balancers conventionally satisfy the calcium requirement — as published by the NRC [3] — with bone-derived microcrystalline hydroxyapatite. Because bone hydroxyapatite carries a fixed stoichiometry of approximately 24% calcium and 11.5% phosphorus, adding it to a boneless fresh-meat base — which is already phosphorus-replete — force-feeds mineral phosphorus into the matrix, raising the very denominator the calcium is meant to balance and locking in a fixed phosphorus load the owner cannot reduce.

The release-B-2.0.0 architecture resolves this by moving the adult maintenance correction to a mineral-phosphorus-free eggshell base paired with a retained soluble calcium salt system (calcium lactate-gluconate and calcium citrate-malate), with no soluble inorganic phosphate salt present. Mass-balance data document a structural phosphorus displacement of −61% for the dog correction (865 → 333 mg/day) and −64% for the cat correction (409 → 147 mg/day) at the validation anchors, with delivered calcium-to-phosphorus ratios re-solved to 1.38 and 1.41 and total calcium-system mass reduced by approximately 38% and 52% respectively. The delivered calcium target is unchanged; what changed is the mass and the phosphorus carried in delivering it.

{{CHART:phosphorus|Correction-borne phosphorus before and after re-basing the calcium system. Replacing bone-derived hydroxyapatite with eggshell plus soluble calcium salts removes 61% of the phosphorus the correction contributes for dogs and 64% for cats, at the validation anchors, while the delivered calcium target is unchanged.}}

The consequence is architectural rather than clinical: the diet moves from a correction-dominated to a diet-governed phosphorus model, so total-bowl phosphorus tracks the owner's protein selection and can be titrated at the bowl without the correction pushing against it. The growth corrections deliberately retain bone hydroxyapatite, and the paper states why, together with the composition of the reproduction co-blend that follows from the same reasoning.

Keywords: BARC Protocol · residual correction · homemade dog food · homemade cat food · home-prepared diet · companion animal nutrition · calcium delivery · phosphorus · eggshell · calcium lactate-gluconate · calcium citrate-malate · microcrystalline hydroxyapatite · feline renal health · mass balance · companion animal supplements

1. Introduction — the structural problem

A boneless fresh-meat bowl is short of calcium and already replete in phosphorus. The conventional way to add calcium to a supplement is bone-derived microcrystalline hydroxyapatite, whose fixed stoichiometry of roughly 24% calcium and 11.5% phosphorus means every gram of the calcium source adds mineral phosphorus to a matrix that does not need it.

The result is a structural contradiction. The corrector raises the phosphorus denominator it is trying to balance, and it locks a high fixed phosphorus load into the correction that the owner cannot dial down by any change of ingredient.

This matters most in cats, and the reason is that phosphorus source and solubility are not interchangeable. Long-term feeding of diets enriched with highly soluble inorganic phosphate produces structural and functional change in the adult feline kidney [1], and no-observed-adverse-effect levels differ by phosphorus source [2]. Bone hydroxyapatite is a low-solubility source and is not implicated by that work. The argument here is therefore not one of source hazard but of total load and controllability: a bone-mineral correction fixes a phosphorus floor that the owner cannot reduce, whatever its solubility class, and so works against any diet-side phosphorus restraint being attempted for a senior or renal-risk animal. Whether that fixed load carries renal risk at these intakes is not addressed by [1,2] and is not claimed here.

2. Methods — the engineering proposition

The proposition is non-clinical and strictly structural:

Removing a fixed-phosphorus calcium source permits calcium delivery to be adjusted without proportionally imposing phosphorus on a variable food matrix.

At release B-2.0.0 the two adult maintenance corrections moved from bone hydroxyapatite to an eggshell-powder calcium base with retained soluble organic calcium salts — calcium lactate-gluconate and calcium citrate-malate. Eggshell is calcium carbonate and carries no phosphorus; the soluble salts buffer availability across the delivered dose. No soluble inorganic phosphate salt is present in the adult correction.

Bone is absent from the diet entirely. The base is boneless and cooked, so the entire calcium requirement is met by the correction's three-source system rather than by feeding bone. This removes the choking, gut-perforation and raw-pathogen hazards of bone-in feeding, and it also removes the variance: a bone fragment's calcium content and its bioavailability are not knowable per meal, whereas a weighed three-salt system is. Calcium is delivered from a declared composition rather than estimated from a bone.

Prior architecture
   fixed bone hydroxyapatite  →  imposes a high fixed phosphorus floor
                              →  works against diet-side restriction

Release B-2.0.0 architecture
   eggshell + soluble calcium salts  →  removes fixed mineral phosphorus
                                     →  total-bowl phosphorus governed by the grocery base

3. Results — mass balance and delivered outcomes

At the validation anchors — a 20 kg dog at 12 units per day and a 4 kg cat at 5 units per day, on a 5 g unit:

Both ratios sit inside adult tolerance, and the change produced no safe-upper-limit breach at 10,000 draws in either the realistic or the four-times-stressed condition [Manuscript 2].

The delivered calcium target is unchanged. The mass displacement is a secondary benefit: a smaller calcium system leaves more of the fixed unit mass available to the rest of the formulation without changing the unit's dimensions or the dose ladder.

3.1 Residual phosphorus

Correction-borne phosphorus fell sharply but did not reach zero. The residual — 147 mg/day for the cat anchor and 333 mg/day for the dog — is carried by the animal-protein palatant fraction, which is characterised as a nutritional input rather than treated as inert [Manuscript 4]. That residual is organic, food-form phosphorus rather than an inorganic phosphate salt. A dedicated low-phosphorus revision could trim it further; that is not a current work item.

4. Discussion — what this does and does not license

The diet moves from a correction-dominated to a diet-governed phosphorus model. Total-bowl phosphorus now tracks the owner's protein choice, so it can be titrated downward at the bowl — egg white, leaner white fish, controlled meat portions, with organ and bone-in avoided — for two populations that benefit: healthy ageing animals, as preventive nutrition, and animals on restricted regimes under direction.

The scope line, held explicitly. Renal protection for a healthy ageing animal is preventive nutrition and is in scope. Treatment of diagnosed kidney disease is a medical decision, is veterinarian-directed, and is out of scope. This architecture enables a lower, diet-governed phosphorus load; it does not treat disease, and nothing in this paper should be read as a therapeutic claim.

5. Growth corrections are deliberately insulated

The re-engineering is restricted to the adult maintenance corrections. The growth corrections retain bone hydroxyapatite, for a specific physiological reason: skeletal mineralisation wants co-delivered phosphorus alongside a bone-matrix calcium source, and the hazard in growth is a calcium ceiling rather than a phosphorus floor: intestinal calcium absorption in the growing dog is regulated differently from the adult [4], and excess absolute calcium intake during growth is associated with skeletal developmental abnormality [5]. That ceiling is managed by a two-sided dose gate [Manuscript 7], not by removing the mineral.

5.1 The reproduction co-blend

The dog reproduction configuration is a co-blend of the two corrections, and its composition follows from the same reasoning. A lactating dam's phosphorus demand is far above an adult's, driven by milk export, so the co-blend is biased toward the growth parent — 1.5 parts adult core to 2.5 parts growth core, at 20 g, with no filler — drawing its phosphorus from the growth half's bone matrix. The ratio fills the unit with premix rather than bulking agent, so the co-blend remains what its manufacturing proposition requires: a blend of two existing premixes, with no separately weighed mineral and no additional assay step.

Delivered against the dam's requirement on a diverse basket: phosphorus 119%, calcium 150%, copper 139%, calcium-to-phosphorus 1.50 (within the 1.0–2.0 band). On a single-protein basket phosphorus delivers 125%. Wilson-C95 at N = 10,000 is 99.869%, with sodium the binding nutrient at 0.06% of draws. Safe-upper-limit headroom was verified after the growth-density bias: the tightest nutrient sits 2.6 times below its limit.

The adult corrections are unaffected by the dam's requirement profile. An adult's phosphorus demand is far below a lactating dam's, and the adult corrections bind on copper rather than phosphorus across 1,000,000 draws [Manuscript 2].

6. Scope and limitations

• The proposition is structural, not clinical. No disease claim is made or implied.
• Correction-borne phosphorus is reduced, not eliminated (§3.1).
• The per-unit masses of the calcium components, the ingredient grades and the supplier specifications are proprietary and not disclosed. What is given is the architecture, the displacement as a percentage, the delivered milligrams per day at the stated anchors, and the delivered ratios.
• The mass-balance figures are engine outputs against the formulation of record, not independent laboratory assays. Finished-unit assay is the release control and is pending the production performance-qualification phase [Manuscript 4].
• The renal argument rests on published feline phosphorus-source work [1,2]; this paper contributes no new animal data.
• Not peer-reviewed as of the date of publication (8 September 2026). Should it later be reviewed or independently replicated, that will be recorded in a subsequent version of this record.

7. Conclusion

Bone-derived hydroxyapatite couples calcium and phosphorus at a fixed stoichiometry, so a correction built on it necessarily adds phosphorus to a matrix already replete in it. Replacing that source with eggshell carbonate plus two soluble calcium salts breaks the coupling. On the modelled bowls it reduces correction-borne phosphorus by 61% for the dog and 64% for the cat, at delivered calcium-to-phosphorus ratios of 1.38 and 1.41, with the delivered calcium target itself unchanged.

The consequence is architectural rather than clinical, and the distinction is deliberate. What the change does is remove a phosphorus load the owner previously could not reduce by any choice of ingredient; whether that reduction carries a clinical benefit at these intakes is not demonstrated here and is not claimed. The growth corrections deliberately retain a bone-mineral source, because the hazard in growth is a calcium ceiling rather than a phosphorus floor, and that ceiling is managed by dose gating instead [Manuscript 7].

References

1. Alexander J, Stockman J, Atwal J, Butterwick R, Colyer A, Elliott D, et al. Effects of the long-term feeding of diets enriched with inorganic phosphorus on the adult feline kidney and phosphorus metabolism. Br J Nutr. 2019;121(3):249–269. doi:10.1017/S0007114518002751
2. Coltherd JC, Alexander JE, Pink C, Rawlings J, Elliott J, Haydock R, et al. Towards establishing no observed adverse effect levels (NOAEL) for different sources of dietary phosphorus in feline adult diets: results from a 7-month feeding study. Br J Nutr. 2021;126(11):1626–1641. doi:10.1017/S0007114521000477
3. National Research Council (US), Committee on Animal Nutrition. Nutrient Requirements of Dogs and Cats. Washington (DC): The National Academies Press; 2006. doi:10.17226/10668
4. Tryfonidou MA, van den Broek J, van den Brom WE, Hazewinkel HAW. Intestinal calcium absorption in growing dogs is influenced by calcium intake and age but not by growth rate. J Nutr. 2002;132(11):3363–3368. doi:10.1093/jn/132.11.3363
5. Hazewinkel HAW. Nutrition in relation to skeletal growth deformities. J Small Anim Pract. 1989;30(11):625–630. doi:10.1111/j.1748-5827.1989.tb01493.x

How to cite

Prasanna M. (2026). Re-Engineering Calcium Delivery for Variable Fresh-Food Diets: A Low-Phosphorus Calcium Architecture for Canine and Feline Nutritional Balancers (Manuscript 1 of 8, Release B-2.1.0). Growlrr Foods Pvt Ltd. Zenodo. https://doi.org/10.5281/zenodo.22647608

The series

This manuscript is one of eight deposited together under release B-2.1.0, with a series cover note carrying the concept DOI and the full DOI list. All eight apply the BARC Protocol, published openly and separately at growlrr.com/barc-protocol.