Effect of Supplementation of Nano Zinc Oxide on Nutrient Retention, Organ and Serum Minerals Profile, and Hepatic Metallothionein Gene Expression in Wister Albino Rats

Partha Sarathi Swain, Somu Bala Nageswara Rao, Duraisamy Rajendran, Dintaran Pal, Sukanta Mondal, Sellapan Selvaraju

A study was conducted to validate the effects of nano form of zinc (NZn) on nutrient digestibility, zinc retention, organ and serum zinc profile, and hepatic metallothionein gene expression in Wistar albino rats (WAR). Nano zinc (NZn) was synthesized through chemical method, by using 0.45 M zinc nitrate [Zn(NO3)2.6H2O] and 0.9 M sodium hydroxide (NaOH). The NZn particle in its oxide form was characterized by TEM-EDAX and XRD, and found to be in nano range (below 100 nm. Zinc was supplemented to the Wistar albino rats (WAR) through synthetic semi-purified diet either without Zn, or as inorganic zinc (IZn; 25 mg/kg), or as synthesized NZn (25, 12.5, 6.25, 3.125 or 50 mg/kg DM) for 60 days. The zinc content was observed to be significantly (P < 0.05) higher in liver, bone, kidney, and serum due to NZn supplementation where NZn-50 had highest zinc content and control had the least, without affecting Fe, Mn, and Cu. NZn at 12.5 mg/kg group rats were either comparable or better than IZn at 25 mg/kg in terms of zinc retention, CP digestibility, zinc level in serum, liver, bone, and kidney suggesting its better bioavailability simultaneously also reduced fecal excretion of zinc to the environment. Metallothionein mRNA expression was upregulated in NZn at 25 mg/kg and NZn at 50 mg/kg than IZn at 50 mg/kg. Thus, in WAR, NZn at half of the ICAR recommendation (25 mg/kg DM) is as effective as inorganic zinc at 100% of recommended dose.