Dietary Zanthoxylum bungeanum seed supplementation alters fat deposition, nutrient utilization and serum parameters by modulating rumen microbial composition and functional in Hu lambs

Zanthoxylum bungeanum seed ( ZBS ) is the main by-product of Zanthoxylum bungeanum Maxim, accounting for approximately two-thirds of the fruit’s total weight. ZBS is a low-cost, high-quality oilseed, and oilseeds can be served as effective feed resources for livestock to improve animal production performance. This study evaluated the effects of different processing methods on ZBS in terms of growth performance, fat deposition, nutrient digestibility, and rumen microbiota in Hu lambs. Forty-five male Hu lambs, approximately 90 days of age and averaging 24 ± 1.8 kg in body weight, were selected for the experiment. The animals were divided into three groups for treatment using a completely randomized design: (1) a basal diet ( CON ); (2) a basal diet supplemented with 8% whole ZBS replacing corn bran ( WZB ); (3) a basal diet supplemented with 8% extruded ZBS replacing corn husk ( EZB ). The results demonstrated that both whole and extruded ZBS can increase the Girth Rib (GR) value, backfat thickness, eye muscle area, abdominal fat weight, tail fat weight, and perirenal fat weight, as well as improve ether extract ( EE ) digestibility in Hu lambs. Additionally, the EZB group exhibited increased ruminal isovaleric acid concentration and enhanced digestibility of organic matter (OM) and acid detergent fiber (ADF). Metagenomic analysis indicated that the EZB group could increase the relative abundance of g_Anareovibrio and s_Anaerovibrio lipolyticus , enhance the activities of GH84 and GT41 enzymes, and improve the ADF digestibility. Spearman correlation analysis further revealed that ZBS could increase the EE digestibility by suppressing the relative abundance of g_Paraprevotella and reducing the activities of CE13 and GT75 enzymes. This study demonstrates that feeding ZBS can enhance the digestibility of dietary crude fat, promote body fat deposition, and improve the utilization efficiency of crude fat and production performance in ruminants by modulating rumen microbiota composition and function, providing a scientific basis for the application of oilseed feeds and optimization of feeding strategies. Not applicable.