Effect of graded levels of zinc supplementation on growth performance and oxidative defense mechanism in rats

–A study was study wasundertaken to investigate the effect of graded levels of inorganic Zn (zinc carbonate) on growthperformance and oxidative defense mechanism inweaned female Sprague Dawley rats for experimental duration of 16 weeks.Ninety weaned rats (93.83 ± 1.308g Bwt) were randomly allotted to 30 replicates with 3 rats in each replicate which were in turn randomly allotted to 5 dietary treatments consisted of supplementing 0, 12, 24, 36 and 48 ppm Zinc carbonate to a basal diet(BD)formulated with purified ingredients without zinc. The zinc supplemented rats showedsignificant (P<0.01) improvement in average daily gain without variation in dose of zinc supplementation.In comparison to basal diet, the feed intake in Zn supplemented rats was significantly (P<0.01) higher from the 4th week and similar trend continued till the end. The lipid peroxidation was higher (P<0.01) in rats fed diet with no zinc supplement. The oxidative stress markers in haemolysate (lipid peroxidation) and liver (TBARS and protein carbonyls) was higher (P<0.01) in BD fed rats and their concentration reduced with Zn supplementation in a dose dependent manner up to 36ppm, while with 48ppm it increased. The reduced glutathione concentration in liver was lower (P<0.01) in rats fed BD and 48ppmZnsupplemented rats, while it increased gradually from 12 to 36ppm Zn supplementation. The activity of glutathione peroxidase and reductase was highest in 36 and 48 ppm Zn supplemented rats followed by rats fed on 24 and 12 ppm zinc supplementation and BD. It indicates that Supplemental Zn at 12, 24, 36 and 48ppm was effective in improving the growth performance, feed intake and oxidative defense except 48 ppm Zn had negative effect on antioxidant activity. Keywords––Antioxidants, feed intake, growth, rats, zinc.