Seaweed eating Sheep

North Ronaldsay Sheep – Eat seaweed, sometimes grass but mostly seaweed.

Sheep = Ovis aries

I am not sure where I heard about these sheep first, this thread is the common perception.

the incredible north ronaldsay sheep (ovis aries), which have adapted to survive mostly off seaweed; eating grass can give them copper poisoning
by inAIDKE

Here is some scientific thoughts.

The biology of the above sheep allows for increased copper absorption. When fed grass, the sheep get copper poisoning (MacLachlan & Johnson, 1982). Human infants can suffer from copper toxicity in the liver, study of these sheep may provide understanding (Heywood et al., 2001; Heywood et al., 2004; Heywood et al., 2005). With higher copper levels in the liver damage and inflation is found, yet evidence of damage is unclear in the brain with the question of homeostasis among higher copper levels (Haywood et al., 2008). Sequestering of the copper might protect neurons. In older sheep, a lacking evidence of damage raises questions (Haywood & Vaillant, 2014).

Arsenic and iodine are also prevalent in seaweed. North Ronaldsay sheep had arsenic levels 2x in urine. Their tissue arsenic levels were 100 times higher. This is compared to Dorset Finn sheep, whose diet consists of grass (Feldmann & Pengprecha, 2000). Dolly the Cloned sheep is a Dorset-Finn.

Ronaldsay and Seaweed.

Laminaria digitata = oarweed

Laminaria hyperborea = tangle and cuvie

L. digitatat and L. hyperborea are brown algae commonly fed on by North Ronaldsay Sheep. Lambs were fed on grass and seaweed diets as a control for microfauna impact. Between the two diets arsenic excretion and intake was not significantly different (Hansen et al., 2003). Guilhem et al. decided to shave horns to test iodine and arsenic. Arsenic is found from seaweed consumption and from grass in the first five months of life. Horns contain iodine from the same portion pointing to transport through milk and placenta (Guilhen et al., 2007). Wool can also be tested for arsenic levels. Lambs eating seaweed have 10 times less arsenic in their wool, still more arsenic than “normal” sheep. Not sure of the downstream but wool reduces the arsenic species (Raab et al., 2002).

Sources

• Haywood S, Müller T, Müller W, Heinz-Erian P, Tanner MS, Ross G. Copper-associated liver disease in North Ronaldsay sheep: a possible animal model for non-Wilsonian hepatic copper toxicosis of infancy and childhood. J Pathol. 2001 Sep;195(2):264-9. doi: 10.1002/path.930. PMID: 11592108.
• Haywood S, Müller T, Mackenzie AM, Müller W, Tanner MS, Heinz-Erian P, Williams CL, Loughran MJ. Copper-induced hepatotoxicosis with hepatic stellate cell activation and severe fibrosis in North Ronaldsay lambs: a model for non-Wilsonian hepatic copper toxicosis of infants. J Comp Pathol. 2004 May;130(4):266-77. doi: 10.1016/j.jcpa.2003.11.005. PMID: 15053929.
• Haywood S, Simpson DM, Ross G, Beynon RJ. The greater susceptibility of North Ronaldsay sheep compared with Cambridge sheep to copper-induced oxidative stress, mitochondrial damage and hepatic stellate cell activation. J Comp Pathol. 2005 Aug-Oct;133(2-3):114-27. doi: 10.1016/j.jcpa.2005.02.001. PMID: 16099232.
• Haywood S, Paris J, Ryvar R, Botteron C. Brain copper elevation and neurological changes in north ronaldsay sheep: a model for neurodegenerative disease? J Comp Pathol. 2008 Nov;139(4):252-5. doi: 10.1016/j.jcpa.2008.06.008. Epub 2008 Sep 12. PMID: 18786681.
• Haywood S, Vaillant C. Overexpression of copper transporter CTR1 in the brain barrier of North Ronaldsay sheep: implications for the study of neurodegenerative disease. J Comp Pathol. 2014 Feb-Apr;150(2-3):216-24. doi: 10.1016/j.jcpa.2013.09.002. Epub 2013 Oct 27. PMID: 24172593.
• Feldmann J, John K, Pengprecha P. Arsenic metabolism in seaweed-eating sheep from Northern Scotland. Fresenius J Anal Chem. 2000 Sep;368(1):116-21. doi: 10.1007/s002160000482. PMID: 11220824.
• Feldmann J, John K, Pengprecha P. Arsenic metabolism in seaweed-eating sheep from Northern Scotland. Fresenius J Anal Chem. 2000 Sep;368(1):116-21. doi: 10.1007/s002160000482. PMID: 11220824.
• Hansen HR, Raab A, Francesconi KA, Feldmann I. Metabolism of arsenic by sheep chronically exposed to arsenosugars as a normal part of their diet. 1. Quantitative intake, uptake, and excretion. Environ Sci Technol. 2003 Mar 1;37(5):845-51. doi: 10.1021/es026074n. PMID: 12666911.
• MacLachlan GK, Johnston WS. Copper poisoning in sheep from North Ronaldsay maintained on a diet of terrestrial herbage. Vet Rec. 1982 Sep 25;111(13):299-301. doi: 10.1136/vr.111.13.299. PMID: 7147642.
• Caumette G, Ouypornkochagorn S, Scrimgeour CM, Raab A, Feldmann J. Monitoring the arsenic and iodine exposure of seaweed-eating North Ronaldsay sheep from the gestational and suckling periods to adulthood by using horns as a dietary archive. Environ Sci Technol. 2007 Apr 15;41(8):2673-9. doi: 10.1021/es062241y. PMID: 17533823.
• Raab A, Hansen HR, Zhuang L, Feldmann J. Arsenic accumulation and speciation analysis in wool from sheep exposed to arsenosugars. Talanta. 2002 Aug 16;58(1):67-76. doi: 10.1016/s0039-9140(02)00257-6. PMID: 18968735.