Safety Evaluation Of Quercetin As A Feed Additive

The acute toxicity test, Ames test, micronucleus test of bone marrow cell, sperm abnormality test,30d feeding test in rats and56d feeding test in laying hens were conducted to comprehensively andsystematically evaluate the safety of quercetin as feed additive. This will provide a theoretical basisfor applying quercetin in animal production as a kind of green, natural and functional feed additives.The study was summarized by three parts as belows:1. Acute toxicity:20mice (weighing18-22g,10males and10females)were administeredquercetin by oral gavage at a dose level of10g/kg body weight twice over4h intervals and observed14d for any signs of toxicity. No abnormality and no death were observed. It suggested that themedian lethal dose of quercetin is greater than10g·(kg·bw)-1, and quercetin is non-toxic substances infact.2. Mutagenicity:①Ames test: Salmonella typhimurium mutant strains (TA97, TA98, TA100andTA102) were randomly divided into7groups of each strain. Each strain was treated by quercetin atlevels of8,40,200,1000,5000μg per vessel; Apart from the quercetin test groups,2other groups ofeach strain received the distilled water at a level of0.1ml per vessel (negative control) and sodiumazide at a level of1.5μg per vessel (positive control) or dexon at a level of50μg per vessel (positivecontrol) or2-acetamidofluorene at a level of10μg per vessel (positive control) or1,8-Dihydroxyanthraquinone at a level of50μg per vessel (positive control) with S9and without S9.Each dose was repeatedly used in three vessels and twice repeated for each experiment. Comparedwith negative control, the amount of mutated bacterial colony in the positive control and control wassignificantly increased (P<0.01), no treatment effect was observed in the amount of mutated bacterialcolony in quercetin treatments (P>0.05), and not in a dose-dependent manner. It suggested thatquercetin didn’t affect the Salmonella typhimurium reverse mutation rate;②Micronucleus test ofbone marrow cell:50Kunming mice (weighing25-35g,25males and25females) were randomlydivided into5groups of10mice. Quercetin was administered to mice at levels of0.5,5,10g/kg bodyweight,0.5%carboxymethyl cellulose was administered to negative control mice by oral gavage, andcyclophosphamide was administered to positive control mice by intraperitoneal injection at a level of40mg/kg body weight. Dose of twice administration was conducted over24h intervals. Comparedwith negative control, the micronuclear rate in the positive control was significantly increased(P<0.01), no treatment effect was observed in the micronuclear rate and the PCE/RBC ratio (P>0.05),and not in a dose-dependent manner. These results indicated that micronucleus rate was not affectedby quercetin, and quercetin was not cytotoxic;③50Kunming mice (weighing25-35g,50males)were randomly divided into5groups of10mice. Quercetin was administered to mice at levels of0.5,5,10g/kg body weight,0.5%carboxymethyl cellulose was administered to negative control miceby oral gavage, and cyclophosphamide was administered to positive control mice by intraperitonealinjection at level of40mg/kg body weight o. d. for5days. Compared with negative control, spermdeformity rate in the positive control was significantly increased (P<0.01), no treatment effect wasobserved in sperm deformity rate (P>0.05), and not in a dose-dependent manner. It suggested thatquercetin didn’t induce sperm deformity in mouse.3. Chronic or subchronic toxicity test:①30d feeding test in Rats:80Wistar rats (weighing150-180g,40males and40females) were randomly allotted into four treatments of20rats. Fourtreatments were fed complete feed supplemented with0.0%,0.4%,2%,10%quercetin for30d. Nostatistically significant increases or decreases in weight gain, feed intake and feed conversion rate ofmale, female rats in any group of quercetin-treated were observed in comparison to control. Also, noclinical symptoms of toxicity were observed in any rats;②56d feding test in laying hens:240Hessian laying hens (29weeks old) were randomly assigned to4treatments consisting of6replicatesof10hens and were fed with diet containing quercetin at0.0%,0.02%,0.04%,0.06%for8weeks. No statistically significant increases or decreases in weight gain, feed intake and feed conversion rate oflaying hens in any group of quercetin-treated were observed in comparison to control. Additionally,no clinical symptoms of toxicity were observed in any hens. These results indicated that quercetinimproved performance in laying hens and Wistar rats, and was not chronic and/or subchronic toxic.In summary, under the present experimental conditions, quercetin was not acute toxic, chronic orsubchronic toxic, nor mutagenic. It suggested that quercetin was not acute toxic, mutagenic andchronic toxic and/or subchronic in vivo and in vitro and further proved quercetin to be a safe feedadditive in animal production.