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Senior laying hens were fed super-doses of Vitamin D daily (human equiv. of 144,000 IU) – May 2024

Dietary Super-Doses of Cholecalciferol Fed to Aged Laying Hens Illustrates Limitation of 24,25-Dihydroxycholecalciferol Conversion

Developments in Nutrition Volume 8, Issue 5, May 2024, https://doi.org/10.1016/j.cdnut.2024.102156
Matthew F Warren 1, Pete M Pitman 2, Dellila D Hodgson 1, Nicholas C Thompson 3, Kimberly A Livingston 1

Older humans taking high concentrations of vitamin D3 supplementation for a prolonged time may be at risk of vitamin D toxicity. It is unclear how dietary super-doses (10,000 times greater than the requirement) can affect vitamin D3 status in aged animals. Aged laying hens could be a model to compare vitamin D3 supplementation effects with women in peri- or postmenopausal stages of life.

We investigated the dietary super-dose impacts of cholecalciferol (vitamin D3) on vitamin D3 status in aged laying hens in production.

Forty-eight 68-wk-old Hy-Line Brown laying hens were individually housed in cages with 8 hens per dietary treatment for 11 wk. Hens were randomly assigned to 1 of 6 treatment groups of dietary vitamin D3 supplementation and consumed ad libitum. Supplementation concentrations were 400, 800, 7400, 14,000, 20,000, and 36,000 IU D3/kg of feed. At the end of the study, all hens were sacrificed, and tissue samples and feces were collected. Plasma and egg yolk vitamin D3 metabolites, calcium and phosphorus composition of eggshells, ileal digesta, and feces were measured. Duodenal, ileal, liver, and kidney gene expression levels were also measured.

We observed that increasing dietary vitamin D3 increased plasma vitamin D3 and egg yolk vitamin D3 (P < 0.0001 for both sites). We also observed an increase in plasma 24,25-dihydroxycholecalciferol as dietary vitamin D3 concentrations increased (P < 0.0001). The plasma 25-hydroxycholecalciferol:24,25-dihydroxycholecalciferol ratio exhibited an asymptotic relationship starting at the 14,000 IU/kg D3 treatment.

Dietary super-doses of vitamin D3 led to greater plasma and egg yolk vitamin D3 concentrations, which shows that aged laying hens can deposit excess vitamin D3 in egg yolk. We suggest future research should explore how 24-hydroxylation mechanisms are affected by vitamin D3 supplementation. Further understanding of 24-hydroxylation can help ascertain ways to reduce the risk of vitamin D toxicity.
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Note: No decrease in egg production, and the eggs had a lot more vitamin D

IU Computations by VitaminDWiki

Some chickens got 36,000 IU of vitamin D per kg of feed
Those chickens consume 100 gram of feed/day = 3,600 IU
Those chickens weigh 2 kg each, so they got 1,800 IU per kg
A human might weight 80 kg
So the vitamin D dose for a human would be 1,800 X 80 = 144,000 IU

VitaminDWiki - Overview Veterinary and vitamin D contains:

Veterinary category has 148 items

Animals need Vitamin D too

Pets as well

Farm Vets are paid when their "patients" are healthy,
   vs doctors who are paid only when "patients" become sick

_Cows are routinely given 30 IU per kilogram (which would be 10,000 IU for a 150 lb person)
Same information is available on Cattle need 66 IU of vitamin D per pound
The US RDA of vitamin D for cows is 13 IU per kilogram (which would be 4,300 IU for a 150 lb 'cow')
Virtually all US farmers who raise livestock use feed which is supplemented with vitamin D
Merick Vet Manual supplement if not have UV or sunlight