@conference {40556,
	title = {Cadmium accumulation in liver and kidney of sheep grazing ryegrass/white clover pastures},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {54},
	year = {1994},
	month = {Jan},
	pages = {31-34},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Pastures growing on soils fertilised with phosphatic fertilisers 
accumulate cadmium (Cd) in their plant tops in proportion to substrate 
concentrations.  Sheep grazing pastures absorb some of this Cd.  To quantify 
the rate with which Cd is accumulated in sheep tissue, three replicated 0.4 
ha blocks were fertilised with either 333 kg/ha of single superphosphate only 
(control) or amended with CdSO4 to give 274g Cd/ha (high-Cd), and set stocked 
with 10, three months old Romney wether lambs.  Cadmium (Cd) concentrations were  
determined in liver, kidney, proximal duodenal and skeletal muscle tissue of  
sheep, ingesting either (means {\textpm} s.e.) 266{\textpm}22 (control) or 746{\textpm}58 (high-Cd) ug  
CD/day from three to six months or 290{\textpm}21 and 721{\textpm}72 ug Cd/day over six to  
eighteen months.  Cadmium concentrations in kidney and liver tissue increased  
markedly over the first three months: 0.042{\textpm}0.006 to 0.32{\textpm}0.03 (Control) and  
0.57{\textpm}0.04 (high-Cd) ug Cd/g fresh tissue, and 0.04{\textpm}0.006 to 0.12{\textpm}0.02  
(Control) and 0.31{\textpm}0.06 (high-Cd) ug Cd/g fresh tissue, for kidney and liver  
respectively.  Although total Cd content continued to increase, as organ size  
increased, over the next 12 months daily accumulation rates in both tissues  
were much lower compared with those over the first three months.  For  
example, daily Cd accumulation in kidney decreased from 0.25{\textpm}0.002 to  
0.06{\textpm}0.01 and 0.47{\textpm}0.04 to 0.32{\textpm}0.05 (ugCd/d) for sheep from the control and  
high-Cd pastures respectively.  Total Cd content in kidney and liver combined  
accounted for approximately 0.25\% of total Cd ingested by sheep age three to  
six months but this significantly decreased to 0.1\% in sheep age six to 
eighteen months. 
 
At higher Cd intakes increased metallothionein protein synthesis in kidney and  
liver tissue enabled animals to be more efficient in sequestering Cd.  This  
resulted in reduced accumulation of Cd in muscle tissue of sheep on the high- 
Cd pastures (2.0{\textpm}0.04 and 5.0{\textpm}0.08 ng Cd/g) compared with those grazing the  
control pasture (4.0{\textpm}0.6 and 14{\textpm}5 ng Cd/g) in animals from the first and  
second periods respectively. 
 
The results from this study show that it is the first few months after weaning  
that fastest uptake into kidney occurs and therefore strategies to reduce Cd  
absorption and subsequent accumulation, e.g. by increasing zinc in the diet,  
should focus on young animals. 
 },
	issn = {1176-5283},
	author = {Lee J and Grace ND and Rounce JR}
}
