Study On Adsorption Of Dietary Aflatoxin By Nanometer Silicate Particle (NSP) In Swine

In the present work, a novel high affinity sorbent for aflatoxin (NSP) was constructed by nano-technology. The objective of this study was to evaluate the ability of NSP to adsorb aflatoxin (AF) in vitro and the efficacy of NSP to protect against aflatoxicosis of pigs and to reduce aflatoxin residues in body tissues (in vivo).The influence of shaking time, NSP amount, solution pH and equilibrium temperature on the adsorption of NSP for aflatoxin was studied and the influence of modification on adsorption was also evaluated. The results showed that the adsorption of NSP for aflatoxin was strong and quick, the adsorption reached equilibrium after 60 min, the desorption rate of aflatoxin from NSP was low and less than 10% (the desorption rate of B₁, B₂, G₁ and G₂ were 6.75%, 8.21%, 7.18%, 9.03% respectively), which was a chemisorption process. The adsorption of NSP for aflatoxin occured in polylayers, the data was fitted to Freundlich equation; the adsorption of SP for aflatoxin occured in monolayer, the data was fitted to Langmuir equation. Both the adsorption process were spontaneous in thermodynamics, but the adsorption ability of NSP was significantly better than SP in adsorption affinity, capacity and rate, via nano-modification.A total of 144 crossbred (Duroc×Landrace×Large white) weaned barrows and gilts (mean body weight, 29.8±1.3 kg) were identified by individual ear tags and tattoos, and randomly assigned to six treatment groups by sex (three replicates per treatment with eight pigs per replicate), housed in concrete-floored indoor pens, and provided with corn/soybean diets and water ad libitum. The diets either met or exceeded critical nutrient concentrations, as recommended by the National Research Council (1998). Six dietary treatments of control feed without addition of NSP and AF, 0.3% SP, 0.3% NSP, 0.1 mg/kg AF, 0.1 mg/kg AF plus 0.3% SP, 0.1 mg/kg AF plus 0.3% NSP were fed to treatment groups for 90 days.Body weight and feed consumption were recorded to calculate average daily gain (ADG), average daily feed intake (ADFI) and feed/gain (F/G) for each replicate. Upon termination of the feeding trial, 8 randomly selected pigs (4 barrows and 4 gilts) fromeach treatment were slaughtered after a 24h fast. Blood samples were taken via jugular venipuncture and related tissue samples were collected for analysis. After determination of all samples and statistical analysis of the data, main results were obtained as follows:(1) AF can significantly affect overall pig health and growth performance, decrease BW gain and feed conversion ratio, reduce antioxidant ability and immune competence, injure hepatic and renal function, then cause significant alterations of related parameters.(2) No significant differences in pig growth performance and other related parameters were found between the control pigs, the pigs fed NSP alone and the pigs fed SP alone, indicating that the silicate material was inert and nontoxic and can be added in diet safely as a feed additive.(3) The addition of 0.3% NSP to AF-contaminated diet can significantly reduce aflatoxin residues in pig tissues to a very low level (the aflatoxin Bi concentration in liver, kidney, Longissimus dorsi and Biceps femoris were 1.65 |J.g/kg, 0.76 ug/kg, 1.13 ug/kg, 1.04 ug/kg respectively), which were less than the most strict EU regulation on toxin residues in animal products (permitted level is 2.0 ppb for aflatoxin Bt and 4.0 ppb for total aflatoxins). SP has the tendency to reduce aflatoxin residues in pig tissues, but the efficacy was markedly less than NSP.(4) With the addition of 0.3% NSP to AF-containing diet, related parameters returned to normal level, showing beneficial effects of NSP on aflatoxicosis. These findings indicated that NSP had the ability to recover the AF-decreased performance, organ damage and to correct aberrations in related parameters, and NSP can effectively diminish the deleterious effects of AF in growing/finishing pigs, and NSP would be a potential ameliorator of aflatoxicosis in pigs. However, with the addition of 0.3% SP to AF-containing diet, the amelioration effects on pig aflatoxicosis were not as great as NSP.The presumed mechanism of action of NSP is to sequestrate aflatoxin in the gastrointestinal tract and form stable sorption complex, thereby prevent gastrointestinal absorption of toxins, then reduce aflatoxin residues in body tissues, and alleviate adverse effects of AF on pigs.In conclusion, as a new nano-adsorbent, no doubt it would be of great significance toapply NSP to solve the aflatoxin contamination problem, and its application can offer a novel approach to the preventive management of aflatoxicosis in animals and provide an encouraging solution to produce safe and low-residue animal products with AF-contaminated feed.