Combining Grape Byproducts to Maximise Biological Activity of Polyphenols in Chickens.

Grape seeds (GS) and grape skins (GK) are natural sources of polyphenols with antioxidant capacity. An experiment was conducted to investigate in chickens the effect of including GS and GK (40 g/kg), individually or combined in different proportions (20 g/kg GS-20 g/kg GK; 30 g/kg GS-10 g/kg GK; 10 g/kg GS-30 g/kg GK), in a corn-soybean diet on growth performance, ileal and excreta contents of total extractable polyphenols (TEP) and tannins, ileal digestibility of protein, plasma and meat α-tocopherol concentration and lipid oxidation (assessed by measuring the thiobarbituric acid reactive substances, TBARS) of stored thigh meat. Neither growth performance parameters nor ileal digestibility of protein were affected by dietary treatments. As compared with control birds, chickens fed the grape byproduct diets showed higher ileal (p < 0.001) and excreta (p < 0.001) TEP and tannins contents. Dietary inclusion of grape byproducts increased α-tocopherol concentration both in plasma (p < 0.001) and in thigh meat (p < 0.01 at 1 d; p < 0.001 at 7 d), as compared with the control group. The highest plasma α-tocopherol concentrations were reached with the 30 g/kg GS-10 g/kg GK and 20 g/kg GS-20 g/kg GK combinations. On day 1 of meat storage, no differences on meat α-tocopherol concentration were found among the grape byproducts treatments but on day 7 of storage, the 20 g/kg GS-20 g/kg GK and 10 g/kg GS-30 g/kg GK combinations led to the highest α-tocopherol concentrations in chicken thigh meat. After seven days of refrigerated storage of meat, the TBARS value was lower in chickens fed the grape byproducts diets than in control birds (1.27 vs. 2.49 mg MDA/kg, p < 0.001). Moreover, among the different grape byproduct treatments, the lowest MDA values were reached with the diets containing GK at rates from 20 to 40 g/kg. In conclusion, dietary incorporation of 40 g/kg of GS and GK added separately or combined increased the plasma and meat α-tocopherol content. Furthermore, the combinations of GS and GK with a proportion of GK of at least 50% optimised α-tocopherol concentration both in plasma and in thigh meat and mitigated lipid oxidation in 7-day stored meat.

Phenolic Metabolites in Plasma and Thigh Meat of Chickens Supplemented with Grape Byproducts.

Grape byproducts are rich sources of polyphenols with powerful antioxidant and health-promoting effects. The impact of supplementing chicken diets with grape byproducts on plasma and thigh meat concentrations of phenolic metabolites was evaluated by analyzing samples by high-performance liquid chromatography quadrupole time of flight mass spectrometry. Chickens were fed three experimental diets: Control diet, Control+8% grape pomace, and Control+0.1% grape seed extract. In plasma, 32 phenolic metabolites were identified, some of which were conjugated catechin/epicatechin metabolites exclusively identified in chickens fed diets enriched in grape byproducts. Also, these chickens showed significantly higher plasmatic concentrations of 21 phenolic metabolites. In thigh meat, 14 phenolic metabolites were identified, but no differences were found between diets. Higher plasmatic tocopherol was found when supplementing diets with grape byproducts, while no changes were observed in meat. Thus, supplementing chicken diets with grape byproducts leads to a significant increase in the circulation of phenolic metabolites and tocopherol.

Impact of a sustained consumption of grape extract on digestion, gut microbial metabolism and intestinal barrier in broiler chickens.

The effect of dietary supplementation with grape extract (GE) at 2.5 and 5.0 g kg-1 of feed on intestinal utilization of polyphenols and gut health of broiler chickens was determined. The ileal digestibility of grape polyphenols was higher for flavan-3-ol monomers [(+)-catechin and (-)-epicatechin] than for dimers (Procyanidins B1 and B2) and galloylated compounds [(-)-epicatechingallate] and no differences among 2.5 and 5.0 g GE per kg dietary treatments were observed. The excreta concentration of benzoic, phenylacetic, phenylpropionic, and cinnamic acids and phenyl-γ-valerolactone phenolic metabolites was higher in birds fed GE, confirming hence the microbial metabolism of grape polyphenols to a relevant extent. Gut morphology and the total ileal mucin content were not modified by the dietary inclusion of GE, but a lower sialic acid concentration was observed in those birds fed a higher concentration of GE. Escherichia coli and lactic-acid bacteria ileal counts were reduced in birds fed GE. Overall, these results prove the extensive intestinal utilization and microbial metabolism of grape polyphenols in broiler chickens. Some antimicrobial and mucin-modulation effects were also observed after a sustained consumption of grape polyphenols during 21 days.

Safety assessment of chronic oral exposure to iron oxide nanoparticles.

Iron oxide nanoparticles with engineered physical and biochemical properties are finding a rapidly increasing number of biomedical applications. However, a wide variety of safety concerns, especially those related to oral exposure, still need to be addressed for iron oxide nanoparticles in order to reach clinical practice. Here, we report on the effects of chronic oral exposure to low doses of γ-Fe2O3 nanoparticles in growing chickens. Animal observation, weight, and diet intake reveal no adverse signs, symptoms, or mortality. No nanoparticle accumulation was observed in liver, spleen, and duodenum, with feces as the main excretion route. Liver iron level and duodenal villi morphology reflect the bioavailability of the iron released from the partial transformation of γ-Fe2O3 nanoparticles in the acid gastric environment. Duodenal gene expression studies related to the absorption of iron from γ-Fe2O3 nanoparticles indicate the enhancement of a ferric over ferrous pathway supporting the role of mucins. Our findings reveal that oral administration of iron oxide nanoparticles is a safe route for drug delivery at low nanoparticle doses.