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.

A fairly simple yet efficient quantitative protocol was developed to investigate plant composition using Fourier-transform infrared spectroscopy (FTIR), through biomass analysis arising from the whole shoot system of Cardoon (Cynara cardunculus L.), Cannabis (Cannabis sativa L.) and Switchgrass (Panicum virgatum L.). An analytical compositional report of the biomasses, serving as a standard method to identify the different chemical groups present, was compared with relevant FTIR spectra and Thermogravimetric Analysis (TGA) thermographs. In order to interpret the highly convoluted absorption spectra, not only a series of reference materials were examined but also extraction protocols were implemented to sequentially isolate the compositional units allowing a spectroscopic monitoring of their progressive removal from the biomass. This approach enabled the assignment and distinction of a series of vibrational peaks and regions identified in the lower wavenumber region. These peaks/regions, were found to be capable of quantitating different chemical units, such as lignin, fats and lipids, even in the case of structural polysaccharides, like cellulose, hemicellulose and pectin, which are the primary constituents of plant cells. Fats and lipids were easily detected at the 3050–2800 cm⁻¹ region, with their concentration determined by the isolated 720 cm⁻¹ and the 728 cm⁻¹ peaks, when present. Lignin concentration was determined via the 1508 cm⁻¹ peak. Hemicellulose is contributing to the 1640, 1245 cm⁻¹ as well as the 1740 cm⁻¹ peak, with its concentration determined in the 850–750 cm⁻¹ region. Cellulose content was quantified via the 895 cm⁻¹ peak, while pectin appeared at the 915 cm⁻¹ peak and also contributed to the 1640 cm⁻¹ signal. Consequently, a better understanding of the vibrational convolution could thus be achieved when studying plant cells where multiple structural units contribute to the spectra. It is therefore expected that plant cellular composition can be adequately revealed with a single FTIR spectrum, without the need for intensive analysis methods, offering a faster and more efficient approach.

The valorization of vinification byproducts portrays a promising bioprocess for the enrichment of animals’ diet with bioactive compounds, such as polyphenols, which could regulate the immune response. Therefore, the impact of dietary grounded grape pomace (GGP), wine lees extract (WYC), and grape stem extract (PE) on the relative transcript level of immune related genes of broiler chickens were examined. Two hundred forty, one-day-old as hatched (male/female) chicks (Ross 308) were allocated to four dietary groups, with four replicate pens each with 15 birds. Birds were fed either a basal diet (CON) or the basal diet supplemented with 2.5% GGP, or 0.2% WYC, or 0.1% PE for 42 d. The relative expression of immune-related genes was investigated using a real-time PCR platform. The mRNA levels of Toll-like Receptor 4 (TLR4) were downregulated (p = 0.039) in the liver of broilers fed the GGP-containing diet compared to the CON, while in the spleen of PE-fed broilers, TLR4 was significantly upregulated (p = 0.043). The mRNA levels of interleukin 8 (IL8) tended to upregulate (p = 0.099) in the bursa of Fabricius and were significantly increased (p = 0.036) in the spleen of broilers fed the PE diet. Vinification byproducts depict a promising sustainable source of polyphenols for the poultry feed industry, but more research is needed under field conditions.