For decades antibiotics have been used in poultry rearing to support high levels of production. Nevertheless, several problems have arisen because of the misuse of antibiotics (i.e., antibiotic resistance, residues in animal products, environmental pollution). Thus, the European Union (EU) as well as the European Food Safety Authority (EFSA) promote action plans to diminish the use of antibiotics in animal production. Alternatives to antibiotics have been studied. Polyphenols (PPs) or organic acids (OAs) seem to be two accredited solutions. Phenolic compounds, such as phenols, flavonoids, and tannins exert their antimicrobial effect with specific mechanisms. In contrast, short chain fatty acids (SCFAs) and medium chain fatty acids (MCFAs), the OAs mainly used as antibiotics alternative, act on the pathogens depending on the pKa value. This review aims to collect the literature reporting the effects of these substances applied as antimicrobial molecules or growth promoter in poultry feeding (both for broilers and laying hens). Organic acids and PPs can be used individually or in blends, exploiting the properties of each component. Collected data highlighted that further research needs to focus on OAs in laying hens’ feeding and also determine the right combination in blends with PPs.

The use of alternative feed ingredients from the Agro-industry could be an efficient tool to improve the sustainability of dairy cow production. Since the richness in polyphenols, olive oil pomace (OOP), produced during olive oil milling, seems a promising by-product to ameliorate milk's nutritional value. The aim of this study was to test the use of OOP produced by means of a new technology (biphasic with stone deprivation) in dairy cow feeding strategy to evaluate the effect on animal performances, rumen microbiota, biohydrogenation processes and milk quality by a multidisciplinary approach. Forty multiparous Italian-Friesian dairy cows, at middle lactation, were randomly allotted into two homogenous groups and fed respectively a commercial diet (CON) and the experimental diet (OOPD) obtained by adding OOP to CON as partial replacement of maize silage. The two diets were formulated to be isoproteic and isoenergetic. The same diets were tested also in an in vitro trial aimed to evaluate their rumen degradability (% DEG). The dietary supplementation with OOP did not affect DM intake, rumen % DEG and milk production. The milk's nutritional quality was improved by increasing several important functional fatty acids (FAs; i.e., linoleic acid, conjugated linoleic acid, oleic acid, vaccenic acid). This finding was related to a decrease in rumen liquor biohydrogenation rate of unsaturated FAs. The stochiometric relation between volatile FA production in the rumen and methanogenesis suggested that OOP lowers the methane potential production (CON = 0.050 mol/L vs OOPD = 0.024 mol/L, SEM = 0.005, P = 0.0011). Rumen microbiota and fungi community did not be strongly altered by OOP dietary inclusion because few bacteria were affected at the genus level only. Particularly, Acetobacter, Prevotellaceae_UCG-004, Prevotellaceae_UCG-001, Eubacterium coprostanoligenes, Lachnospira, Acetitomaulatum, Lachnospiraceae_NK3A20 group were more abundant with OOPD condition (P < 0.05). Data reported in this study confirm that the use of OOP in dairy cow feeding can be an interesting strategy to improve milk nutritional quality increasing functional FA content without compromising the rumen degradability of the diet or causing strong perturbation of rumen ecosystem and maintaining animal performances.

Exposure to air and light lowers the meat quality of chickens, which is mainly determined by the color alteration and accumulation of detrimental products from lipid oxidation. This study tests the effects of 2 supplements rich in polyphenols, Oxilem (OX) and OxiGem (OG), on broiler Ross 308 performance and meat quality in comparison to a control group (C). A total of 105 one-day-old Ross 308 male chicks were allocated to 21 pens and randomly assigned to 1 of the 3 treatments. The trial lasted 42 d. Individual live weight and feed intake per pen were recorded. Proximate analysis, color, cholesterol content and cholesterol oxidation products (COPs), fatty acids (FAs), volatile aldehydes profile, and secondary oxidation products of meat FAs were determined, with analyses for detecting oxidative alterations conducted on breast burgers preserved for 7 d at 4°C. Birds fed OG grew 7 g/d more than those receiving OX, reaching a higher final weight. After slaughtering, meat from the OX group had a higher yellow index compared to C. After 7 d of air and light exposure, the influence on the color parameters of the OG and OX burgers was significantly less pronounced than that of C. Secondary oxidation products of the FAs of the burgers were not significantly affected by the diet regimens. In addition, OX and OG burgers exhibited lower amounts of volatile aldehydes, triol and COPs. These results confirm the effectiveness of OX and OG supplementation against lipid oxidation at the inclusion level used in this trial.

Animal feeding through the reuse of agro-industrial by-products in one of the ultimate goals of sustainable agriculture. Olive oil pomace (OOP) produced as a waste product during olive oil milling has been used as an ingredient in the diet for Holstein lactating cows. Recent findings have shown no decrease in animal performance, feed intake or detrimental effect on rumen microbiota. In contrast, an improvement in C18 polyunsaturated fatty acids has been observed. In this work, the milk protein content from cows fed a commercial diet (CON) or an experimental one supplemented with OOP was determined and compared, and the peptides derived from the simulated gastrointestinal digestion of raw milk were analyzed. After fractionation via RP-HPLC, peptides were characterized for their biological activity on different cell lines. The ability to reduce both the intracellular ROS content and the expression of inflammatory markers, such as Cyclooxygenase, isoenzyme 2 (COX-2) and inducible Nitric Oxide Synthase (iNOS), as well as the remarkable properties to induce cell differentiation and to slow down the proliferation of human intestinal cancer cells, enable us to define them as bioactive peptides. In spite of there being no observed significant difference between the healthy activity of CON and OOP peptides, the results allow us to broaden the knowledge about the biological activity of these bioactive peptides and to confirm that agro-industrial by-products may be successfully incorporated into the feeding strategy of dairy cows.