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|Title: ||Copper, Iodine and Selenium Status in Irish Cattle.|
|Authors: ||Philip, AM|
trace element status
|Issue Date: ||1-Jul-2001|
|Citation: ||Philip, AM, Rogers, MVB, Copper, Iodine and Selenium Status in Irish Cattle, End of Project Reports, Teagasc, 2001.|
|Series/Report no.: ||End of Project Reports;|
Beef Production Series;15
|Abstract: ||At 9 abattoirs throughout the state, samples of blood, liver and kidney were collected from the three cattle categories (cull dairy cows, cull beef cows and finished steers) at slaughter. In all, 2612 cattle were sampled for the following assays: copper (Cu), haemoglobin (Hb) and glutathione peroxidase (GPx, a selenoenzyme) on whole blood, inorganic iodine (I) in plasma, and Cu in liver and Selenium
(Se) in a subset of liver and kidneys.
The survey documented the overall status of Cu, I and Se in Irish cattle at slaughter and compared the trace element status of three categories of cattle. It also examined the effects of housing / season (late spring versus late autumn).
I deficiency was the most prevalent mineral deficiency in all three bovine categories. Overall, in spite of whatever supplementation was being used preslaughter, 69% of samples had low (<50 µg/L) plasma inorganic I status (51% at the end of spring, 84% at the end of autumn).
Overall, in spite of whatever supplementation was being used preslaughter, liver Cu status was low (<20 mg/kg DM) in 19% of samples (11% at the end of spring, 26% at the end of autumn). Liver Cu reflects Cu status more accurately than blood Cu. However, the relationships between Cu levels in liver and blood were poor in these data; it was not possible to predict a blood Cu level accurately from a given liver Cu level. Also, relative to liver levels, blood levels underestimated the extent of low Cu status by a factor of >2, with a wide range of error (0.9-2.6 times). However, as liver biopsy seldom is a practical option in commercial herds, blood tests usually are used for routine assessment of mineral status in live cattle.
GPx levels in whole blood closely reflect blood Se status. In spite of whatever supplementation was being used preslaughter, blood GPx status was low (<40 iu/g Hb) in 11% of samples (4% at the end of spring, 16% at the end of autumn). In a subset of the data, blood GPx and Se levels in bovine kidney and liver had positive linear relationships but predictability was poor. A similar conclusion applies to levels of Se in liver and kidney. Also, liver Se correlated better with blood GPx (R2 = 0.443) than with kidney Se (R2 = 0.264).
Cattle slaughtered off grass in late autumn had lower Cu, I and Se status than those slaughtered out of sheds in late spring.
Finished beef steers and cull suckler cows had lower Cu and Se status than cull dairy cows.
Liver and kidney had few high Cu or Se levels, indicating that current inputs of minerals do not pose a threat of toxicity to cattle, or to the human food chain. Mean PII levels in dairy cows were too low to pose a threat of excessive milk I levels for human consumption.
Other research at Grange shows that trace element supplementation and trace element status in bovine blood, especially from dairy cows, improved nationally in recent years. However, this survey shows clearly that current national inputs of Cu, I and Se are inadequate to maintain normal trace element status in finished steers and cull (especially beef) cows at slaughter.
This report concludes that
current national inputs of Cu, I and Se are inadequate to maintain normal trace element status in finished steers and cull (especially beef) cows at slaughter, and
from current inputs, the risk of Cu or Se toxicity to cattle, or to the human food chain, is minimal.|
|Description: ||End of Project Report|
|Appears in Collections:||AGRIP End of Project Reports|
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