Replacing Fishmeal with Fermented Wheat Protein Improves Nutrient Digestibility and Intestinal Health in Weaned Piglets

Fermented wheat protein (FWP) has a high protein content and is beneficial to intestinal health, making it an ideal alternative to fishmeal (FM). This study evaluated the effects of replacing FM with FWP on growth performance, nutrient digestibility, and gut health in weaned piglets. A total of 144 weaned piglets (28 days old) were randomly divided into three dietary treatments with 48 piglets per treatment for a duration of 28 days. The treatments included a control diet containing 3% FM (CON group), a diet with 1.5% FM and 1.5% FWP (50% FWP replacement), and a diet with 3% FWP (100% FWP replacement). The results showed that replacing FM with FWP did not significantly affect average daily gain, average daily feed intake, or the feed conversion ratio but significantly reduced diarrhea rates (<i>p</i> < 0.01). The 50% and 100% FWP replacement significantly improved the digestibility of crude protein and acid detergent fiber, respectively (<i>p</i> < 0.05). The 100% FWP replacement significantly improved the activity of trypsin and chymotrypsin in the duodenum and jejunum (<i>p</i> < 0.05). Additionally, the 100% FWP replacement significantly enhanced serum total antioxidant capacity, glutathione peroxidase, and immunoglobulin A contents (<i>p</i> < 0.05). The 100% FWP replacement significantly increased villus height in the jejunum (<i>p</i> < 0.01). Moreover, the 100% FWP replacement significantly increased the expression of intestinal-barrier-related genes Zonula Occludens-1 and occludin (<i>p</i> < 0.01) and decreased the expression of inflammation-related genes (<i>p</i> < 0.01). Overall, FWP effectively reduces diarrhea rates, improves gut structure, enhances digestion, and boosts antioxidant and immune functions, particularly at a high replacement ratio (100%). Therefore, FWP can be considered an effective alternative to FM.