Antioxidant Status of Broiler Chickens Fed Diets Supplemented with Vinification By-Products: A Valorization Approach

Abstract

Vinification by-products display great potential for utilization as feed additives rich in antioxidant compounds. Thus, the effect of dietary ground grape pomace (GGP), wine lees extract rich in yeast cell walls (WYC), and grape stem extracts (PE) on the relative expression of several genes involved in liver oxidative mechanisms and the oxidative status of the blood and breast muscle of broiler chickens was investigated. In total, 240 one-day-old as hatched chicks (Ross 308) were assigned to four treatments, with four replicate pens and 15 birds in each pen. Birds were fed either a basal diet (CON) or a basal diet supplemented with 25 g/kg GGP, or 2 g/kg WYC, or 1 g starch including 100 mg pure stem extract/kg (PE) for 42 days. The polyphenolic content of vinification by-products was determined using an LC-MS/MS library indicating as prevailing compounds procyanidin B1 and B2, gallic acid, caftaric acid, (+)-catechin, quercetin, and trans-resveratrol. Body weight and feed consumption were not significantly affected. The relative transcript level of GPX1 and SOD1 tended to increase in the liver of WYC-fed broilers, while NOX2 tended to decrease in the PE group. SOD activity in blood plasma was significantly increased in WYC and PE compared to the CON group. The total antioxidant capacity measured with FRAP assay showed significantly higher values in the breast muscle of PE-fed broilers, while the malondialdehyde concentration was significantly decreased in both WYC- and PE-fed broilers compared to the CON group. The exploitation of vinification by-products as feed additives appears to be a promising strategy to improve waste valorization and supply animals with bioactive molecules capable of improving animals' oxidative status and products' oxidative stability.

Keywords: flavonoids; grape pomace; grape stems; liver; polyphenols; wine lees; wine yeast cells.

Figure 1

Feed additives supplemented in broiler diets: (A) ground grape pomace (GGP), (B) dried wine lees extract (rich in yeast cell walls; WYC), and (C) extract from grape stems included in soluble starch (PE).

Figure 2

Mean and standard error of means (SEM) of relative transcript levels as fold changes of several genes involved in the antioxidant system in the liver of broilers fed the four experimental diets (Control; CON, ground grape pomace; GGP, dried wine lees; WYC, and extract from grape stems included in soluble starch; PE). Bars with different superscript (a, b) between dietary treatments differ significantly (p ≤ 0.05) according to the analysis of variance (ANOVA) using post hoc multiple range test when appropriate.

Figure 3

Means ± SEM of total antioxidant capacity, oxidative stress indicators, and enzyme activities (Units/mL) in the blood plasma of broilers fed the four diets (Control; CON, ground grape pomace; GGP, dried wine lees extract; WYC, and grape stem extract included in soluble starch; PE) at 42 days. Bars with different superscript (a, b) between dietary treatments differ significantly (p ≤ 0.05) according to the analysis of variance (ANOVA) using post hoc multiple range test when appropriate.

Figure 4

Total antioxidant capacity and lipid peroxidation index of breast muscle of broilers fed the four diets (Control; CON, ground grape pomace; GGP, dried wine lees extract; WYC, and grape stem extract included in soluble starch; PE) at 42 days. Bars with different superscript (a, b) between dietary treatments differ significantly (p ≤ 0.05) according to the analysis of variance (ANOVA) using post hoc multiple range test when appropriate.

Figure 5

(A) Discriminant plots separating the four dietary treatments (Control; CON red, ground grape pomace; GGP green, dried winery yeast cell walls; WYC blue, and phenolic extract from grape stems included in soluble starch; PE purple) according to pooled data of the liver’s relative transcript levels and blood plasma and breast muscle antioxidant indicators. (B) Principal component analyses were applied on liver relative transcript levels, blood plasma, and breast muscle antioxidant indicators. L_CAT: catalase relative expression in liver; L_SOD1: superoxide dismutase 1 relative expression in liver; L_GPX1: glutathione peroxidase 1 relative expression in liver; L_GPX2: glutathione peroxidase 2 relative expression in liver; L_iNOS: nitrous oxide relative expression in liver; L_NOX1: NADPH oxidase 1 relative expression in liver; L_NOX2: NADPH oxidase 2 relative expression in liver; L_NOX3: NADPH oxidase 3 relative expression in liver; L_GST: glutathione transferase 2A relative expression in liver; B_FRAP: blood plasma FRAP value; B_ABTS: blood plasma ABTS value; B_DPPH: blood plasma DPPH value; B_MDA: blood plasma MDA concentration; B_CAT: catalase activity in blood plasma; B_SOD: superoxide dismutase activity in blood plasma; B_GPX: glutathione peroxidase activity in blood plasma; B_GST: glutathione transferase activity in blood plasma; B_GR: glutathione reductase activity in blood plasma; M_FRAP: FRAP value in breast muscle; M_ABTS: ABTS value in breast muscle; M_DPPH: DPPH value in breast muscle; M_MDA: MDA concentration in breast muscle.