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The effect of iron supplementation on hepatic copper content of growing lambs

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Abstract

Implications Dietary iron increases hepatic iron storage while decreasing copper. However, there was no effect on other minerals. Introduction Copper (Cu) is considered to be one of the most important trace elements that are required for normal biological function in all living higher organisms (Suttle, 2010). Clinical copper deficiency is recognised as an important nutritional problem in ruminant animals resulting in loss of performance along with a decrease in health. The main cause of deficiency is due to interactions with other minerals, and the main factors influencing Cu metabolism in sheep are molybdenum, sulphur and iron. The interaction between molybdenum (Mo) and sulphur (S) has been well documented and shown to be mediated via the production of thiomolybdates in the rumen (Gould and Kendal, 2011). The mechanism by which Fe alters Cu metabolism has not been well characterised or quantified. Therefore, the aim of this study was to investigate the effects of dietary Fe and S on hepatic Cu storage.
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The effect of iron supplementation on hepatic copper content of growing lambs
S M Sefdeen, A M Mackenzie, R G Wilkinson
Harper Adams University, Newport, Shropshire, UK Email:ssefdeen@harper-adams.ac.uk
Implications Dietary iron increases hepatic iron storage while decreasing copper. However, there was no effect on other
minerals.
Introduction Copper (Cu) is considered to be one of the most important trace elements that are required for normal
biological function in all living higher organisms (Suttle, 2010). Clinical copper deficiency is recognised as an important
nutritional problem in ruminant animals resulting in loss of performance along with a decrease in health. The main cause
of deficiency is due to interactions with other minerals, and the main factors influencing Cu metabolism in sheep are
molybdenum, sulphur and iron. The interaction between molybdenum (Mo) and sulphur (S) has been well documented and
shown to be mediated via the production of thiomolybdates in the rumen (Gould and Kendal, 2011). The mechanism by
which Fe alters Cu metabolism has not been well characterised or quantified. Therefore, the aim of this study was to
investigate the effects of dietary Fe and S on hepatic Cu storage.
Material and methods Thirty-six Texel-cross lambs (33.2 kg liveweight, s.e.d 0.41) were blocked by weight and sex and
then randomly allocated to one of four treatments, housed in individual pens. Lambs were fed an isonitrogenous,
isoenergetic diet based on dried grass, formulated for them to gain 200g /day (AFRC, 1993) over a 6 week study. All
lambs were fed the basal diet, with the control lambs having no additional supplements, lambs on the Low Fe diet were
supplemented with 250 mg Fe per kg DM, lambs on the Mid Fe diet were supplemented with 500 mg Fe per kg DM and
lambs on the High Fe diet were supplemented with 750 mg Fe per kg DM. Lambs were weighed and blood sampled
weekly. After 6 weeks, the lambs were slaughtered in a commercial abattoir and liver samples collected. Mineral levels of
liver and blood plasma were analysed using ICP-MS (Cope et al., 2009). All data was analysed by analysis of variance
(ANOVA) as a random block design (GenStat, 15th edition) and for blood data week one was used as a covariate. Daily
liveweight gain (DLWG) was calculated by regression analysis and analysed by ANOVA. Significance differences
between means were tested using the protected least significant difference (LSD).
Results Control and low Fe lambs trended to have higher hepatic Cu concentrations compared with the Mid and High Fe
fed groups (P=0.067). In addition, the total liver Cu store was significantly greater (P=0.016) in control and Low Fe fed
groups compared with the Mid and High groups. Lambs fed High and Mid Fe diet had significantly greater (P <0.001)
liver Fe concentration than Control and Low groups (Table 1). There was no effect (P>0.05) of dietary treatments on
DLWG or feed intake. Plasma Fe was significantly higher (P <0.05) in week 4 and 6 of the experiment in Fe supplemented
lambs. However, plasma Cu concentration did not show any significant influences though-out the 6 weeks experimental
period. There was no effect (P >0.05) of dietary treatments on the haematology parameters and superoxide dismutase
activity (SOD) at any time point to the end of trial.
Table 1 Effect of dietary level of Fe on hepatic Cu and Fe concentration in growing lambs (g/g DM)
Minerals
Treatment
s.e.d. P Value
Control Low
(250 Fe mg/kg -1)
Mid
(500 Fe mg/kg -1)
High
(750 Fe mg/kg -1)
Cu 313.30 322.30 242.80 205.00 49.250 0.067
Fe 362.30a 407.00
a 551.00
b
631.90
b
37.040 <0.001
Conclusion With increasing dietary Fe level, liver Cu concentration decreased but Fe concentration increased in
accordance to inclusion dose. Dietary Fe levels had no effect on lamb performance parameters and blood components
values. The mechanism by which dietary Fe reduces liver Cu needs to be elucidated.
Acknowledgements Kurdistan regional government (KRG) is gratefully acknowledged for funding this study.
References
AFRC. 1993. CAB International, Wallingford, UK.
Cope, C. M., A. M. Mackenzie, D. Wilde, and L. A. Sinclair. 2009. Journal of Dairy Science 92, 2128–2135.
Gould, L., Kendall, N. R., 2011. Nutr. Res. Rev. 24, 176–182.
Suttle, N. F., 2010, 4th Edition. CABI Publishing.
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