Improving the Nutritional Value of Plant Protein Sources as Poultry Feed through Solid-State Fermentation with a Special Focus on Peanut Meal—Advances and Perspectives

The poultry industry has been and is still suffering considerable challenges because of the increasing price of soybean meal. Therefore, it is imperative to find alternative, high-quality plant protein sources. Peanut meal (PNM), a by-product of peanut oil extraction, is abundant in crude protein (40.1–50.9%), making it a potential plant protein source. However, nutritional and non-nutritional limitations are detrimental to its application in poultry diets, such as an imbalance in amino acid composition, phytate and the risk of aflatoxins pollution. As a processing technique, solid-state fermentation has been used to reduce phytate and improve the nutrient availability of plant protein sources in the feed industry. It is a promising approach to improving the application of PNM in poultry diets. There are several advantages to the solid-state fermentation of PNM, such as low-cost equipment, high productivity, the stability of the product and the minimization of energy consumption. Currently, there is still a lack of synthesized information on the application of solid-state fermented PNM in poultry. This review summarized the limiting factors for PNM application in poultry feed and the improvement of solid-state fermentation on the nutritional value of plant protein sources so as to evaluate the feasibility of improving the nutritional value of PNM as poultry feed through solid-state fermentation. We hope to shed some light on the selection of protein resources in future research.