UVB Exposure of Farm Animals: Study on a Food-Based Strategy to Bridge the Gap between Current Vitamin D Intakes and Dietary Targets
Alexandra Schutkowski, Julia Krämer, Holger Kluge, Frank Hirche,
Andreas Krombholz, Torsten Theumer, Gabriele I. Stangl gabriele.stangl at landw.uni-halle.de
Vitamin D deficiency is a global health problem. This study aimed to investigate the efficacy of ultraviolet (UV) B radiation for improving vitamin D3 content of eggs and meat. In a two-factorial design hens that received diets with 0 (-D3) or 3,000 IU (+D3) vitamin D3/kg were non-exposed (-UVB) or exposed to UVB radiation (+UVB) for 3 h daily over 4 weeks. Data show that UVB radiation was very effective in raising the vitamin D3 content of egg yolk and meat.
Egg yolk from +UVB/−D3 hens had a higher vitamin D3 content (17.5±7.2 µg/100 g dry matter (DM)) than those from the –UVB/+D3 group (5.2±2.4 µg/100 g DM, p<0.01).
Vitamin D3 content in egg yolk of vitamin D3-supplemented hens could be further increased by UVB radiation (32.4±10.9 µg/100 g DM). The content of 25-hydroxyvitamin D3 (25(OH)D3) in the egg yolk also increased in response to UVB, although less pronounced than vitamin D3.
Meat revealed about 4-fold higher vitamin D3 contents in response to UVB than to dietary vitamin D3 (p<0.001).
In conclusion, exposure of hens to UVB is an efficient approach to provide consumers with vitamin D3-enriched foods from animal sources.
Received: March 13, 2013; Accepted: June 10, 2013; Published: July 24, 2013
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- Wanted to increase vitamin D levels in chicken meat and eggs without encountering the bio-addition limits which most governments have imposed
- Most of the vitamin D creation appears to be on the legs – which do not have feathers
Legs have 190X more pre-vitamin D than other portions of the chicken
- UVB illumination 3 hours total daily
- UVB intensity was estimated to be the same amount as natural sunshine would provide
- 2,500 IU vitamin D3/kg of feed – not body weight
- Egg yoke with UVB + vitamin D got to 1300 IU per 100 grams
Since a yoke appears to weigh 18 grams, this is 70 IU per yoke
- Free range eggs have 4X as much vitamin D
Conventional: 34 IU. Pastured avg: 136 - 204 IU: thus pastured eggs had even more vitamin D per yoke than vitamin D in feed + UVB
- 200 IU per 100 gram of egg yoke when add vitamin D to poultry feed in Europe – Aug 2011
- In less than 3 weeks chickens have problems if they do not have vitamin D
- Vitamin D in US eggs: 2 to 18 IU – March 2013
- Vitamin D from sun barely increased when lower half of body was also exposed – Jan 2015
Perhaps the human body is as smart as the chicken and does not bother to put
pre-vitamin D on parts of the skin which rarely see daylight