Effect of Mulberry Leaf Powder of Varying Levels on Growth Performance, Immuno-Antioxidant Status, Meat Quality and Intestinal Health in Finishing Pigs

Background: The purpose of the research was to investigate the effect of mulberry leaf powder (MP) of varying levels on growth performance, immuno-antioxidant status, meat quality and intestinal health. A total of 120 healthy finishing pigs (Duroc × [Landrace × Yorkshire], 72.2 ± 4.8 kg) were selected for this experiment and divided into four treatments, according to randomized complete block design, with three replicates of 10 pigs each (barrow:gilt = 1:1). The dietary treatments were as follows: (1) Ctrl, corn-soybean meal basal diet; (2) MP_6: basal diet with 6% MP. (3) MP_9: basal diet with 9% MP; (4) MP_12, basal diet with 12% MP. The whole experiment lasted for 33 days. Results: Compared to the Ctrl, dietary supplementation of 9% MP had no negative effects on growth performance, antioxidative capacity, intestinal digestive enzyme activities and inflammatory factors, carcass trait, the lipid profile and amino acid of muscle or related mRNA expression. MP_6 and MP_12 showed detrimental effects on average daily gain (p < 0.05) and digestibility (p < 0.05) of dry matter, crude protein and gross energy. Furthermore, MP_9 could improve (p < 0.05) the level of serum immunoglobulin M, enhance (p < 0.05) the a*(24h) of meat, up-regulate (p < 0.05) the mRNA expression of occludin and Mucin-2, increase (p < 0.05) the relative abundance of Bifidobacterium and decrease (p < 0.05) the relative abundance of Campylobacter in the hindgut. Conclusion: Summarizing our study, dietary supplementation of 9% MP had no negative effects on growth performance, antioxidative capacity, intestinal digestive enzyme activities and inflammatory factors, carcass trait, the lipid profile and amino acid of muscle, or related mRNA expression. Furthermore, MP_9 could improve serum immunity, enhance meat quality, up-regulate the mRNA expression related to the mechanical and chemical barriers and enrich the beneficial microbiota of the hindgut. Hence, dietary supplementation of 9% MP in finishing pigs may be advisable.