UK ruminant farmer understanding of copper-related terminology.

Copper provision is not straightforward in ruminants. Other dietary elements such as iron and molybdenum in combination with sulphur are able to interfere with copper availability, absorption and function. These complexities surrounding copper availability in cattle and sheep prevent the simple calculation of copper requirements. Previous research has established that UK farms are failing to provide copper in an effective manner, with some over-supplying and others under-supplying. Copper terminology is not consistently understood by professionals in the agricultural industry; potentially resulting in confusing or misinformation being passed on to farmers. The present work found that most (84 %) farmers felt they lacked understanding of copper related problems and their associated terminology. However, farmers who felt they had the least knowledge appeared more likely to underestimate their knowledge, and those who felt more confident in their knowledge were more likely to be overestimating it. Simple over- and under-supply of copper were only recognised by a small proportion (17 %) as causes of copper related problems while more complex issues were better recognised (27 %) as potential causal factors. However, the more specific terminology relating to the molybdenum-sulphur antagonism was poorly understood by most respondents (96 %).

X-ray absorption spectroscopy of copper and iron in sheep digesta.

BACKGROUND: The bioavailable supply of copper to ruminants has long been problematic. Complexities in supply exist due to interactions with other dietary elements in the rumen, most notably with iron or molybdenum in combination with sulphur, which can result in copper binding preventing its absorption. The molybdenum-sulphur-copper interaction has been extensively studied over the years. However, very little is known about the iron-sulphur-copper interaction, especially its mode of action in the gastrointestinal tract. METHODS: In the present work digesta from the rumen and jejunum of sheep fed a high copper, sulphur and iron diet was analysed using X-ray absorption spectroscopy (XAS). RESULTS: X-ray absorption fine structure (XAFS) and X-ray absorption near edge structure (XANES) indicated that all of the copper and iron had changed in bonding in the rumen and that the oxidation state of the elements had been reduced into a mix of Fe2+ & Fe3+ and Cu+ with some Cu0. CONCLUSION: The copper compounds were most likely to be thiol co-ordinated in line with Cu+ chemistry. Changes to the copper compounds took place in the jejunum, although thiols were still highly favoured the possible existence of a copper-iron-sulphur complex which also included oxygen and chloride was also observed. This possibly has some resemblance to the crystal structure of bornite.

Comparison of X-ray absorption spectra from copper-loaded bovine and ovine livers.

BACKGROUND: Copper toxicity and hepatic copper accumulation pose a serious risk to ruminant health and production. Differences in the copper-handling mechanisms of cattle and sheep have been noted, not only in comparison to each other, but also in comparison to 'copper-tolerant' monogastric species. Ruminants appear less able to cope with rising liver copper concentration than monogastric counterparts, with sheep in general less able to cope with elevated copper intake than cattle. METHODS: X-ray absorption spectroscopy (XAS) was used to investigate the differences between the livers of these species at high copper status. RESULTS: The X-ray absorption fine structure (XAFS) and X-ray absorption near edge structure (XANES) spectra indicated that the hepatic copper compound is most likely to be bound to metallothionein; consistent with monogastric species. CONCLUSION: Although, most likely stored as copper-metallothionein, there may be a role for glutathione as a short-term, intermediate copper buffer which may have more relevance to sheep than cattle. The potential that thiomolybdate bound copper can be stored in the liver could not be ruled out.

Copper physiology in ruminants: trafficking of systemic copper, adaptations to variation in nutritional supply and thiomolybdate challenge.

Ruminants are recognised to suffer from Cu-responsive disorders. Present understanding of Cu transport and metabolism is limited and inconsistent across vets and veterinary professionals. There has been much progress from the studies of the 1980s and early 1990s in cellular Cu transport and liver metabolism which has not been translated into agricultural practice. Cu metabolism operates in regulated pathways of Cu trafficking rather than in pools of Cu lability. Cu in the cell is chaperoned to enzyme production, retention within metallothionein or excretion via the Golgi into the blood. The hepatocyte differs in that Cu-containing caeruloplasmin can be synthesised to provide systemic Cu supply and excess Cu is excreted via bile. The aim of the present review is to improve understanding and highlight the relevant progress in relation to ruminants through the translation of newer findings from medicine and non-ruminant animal models into ruminants.