The promise of pectic oligosaccharides as a novel sustainable additive in poultry production: A systematic review

The prohibition of antibiotic growth promoters in animal feeds due to their well-known hazards has driven the accelerated research and development of novel practicable alternatives, among which functional oligosaccharides are characterized as one of the most promising candidates because of their stability, safety and excellent biological activities. Pectic oligosaccharides (POS) are an emerging class of functional oligosaccharides obtained through physicochemical or biological degradation (especially the enzymolysis) of pectins (a crucial kind of plant cell wall components). The preparation of POS is economically feasible, which not only overcomes the anti-nutritional impacts of native pectins in plant ingredients, but also obtains other benefits for poultry, because the prepared POS possess numerous functions, such as optimizing gut microbiome via both prebiotic and non-prebiotic actions, regulating lipid metabolism and immune responses, as well as exerting antioxidant and antitumor properties. Noticeably, the above functions of POS that depend largely on their structure have been primarily validated in laboratory animals or in vitro models, while the related researches in poultry or other farm animals are relatively few. The present review systematically discusses the preparation methods of POS, their biological activities and underlying mechanisms that may benefit poultry growth and health, as well as their structure-activity relationships. We also summarize the currently limited evidences on the positive roles (such as improvements of production performance along with intestinal and genital health) of POS in poultry nutrition, thus supporting the promise of POS as a novel sustainable additive in poultry diets. Since the application of POS in feeds is still underexplored, future studies deserve to be conducted to elucidate the definite mechanisms together with the structure-effect and dose-effect relationships of POS, as well as the synergy between POS and other additives (e.g. probiotics) in poultry nutrition. Such research efforts are anticipated to further extend the role of POS as a cost-efficient and sustainable additive in advancing poultry production.