Extrusion processing of peanut vine-corn-urea mixture promotes the growth performance of fattening cattle by modulating rumen fermentation and microbiota

Objective: This study aimed to develop a new type of extruded compound feed, characterize its rumen degradation parameters and investigate the effects on growth performance, diet digestibility, rumen fermentation and bacterial communities of fattening cattle. Methods: To determine the optimal ratio, we measured key nutritional components and ruminal degradability using in situ nylon bag technology. Subsequently, 36 fattening cattle (618.0 ± 23.3 kg) were randomly assigned to the control group (CON) and the extruded compound feed group (EXP), with 18 cattle per group. The feeding experiment lasted 60 d. Results: As corn content increased in the extruded compound feed, the effective degradability of neutral detergent fiber (NDF) increased (p = 0.056). When the proportions of peanut vine: corn: urea were 65:30:5, the effective degradability of NDF reached the highest value of 27.3%. This extruded compound feed was used in the subsequent feeding experiment. The EXP group had higher average daily feed intake (CON vs. EXP: 16.0 kg vs. 17.2 kg, respectively, p < 0.001) and average daily gain (CON vs. EXP: 1.51 kg vs. 1.72 kg, respectively, p < 0.001). The feeding profit per head of fattening cattle in the EXP group was 7.1 US dollars higher than that in the CON group. The 16S rRNA sequencing results showed that the relative abundance of Bacteroidetes (CON vs. EXP: 37.7% vs. 59.2%, respectively, p < 0.001) and Prevotella_1 (CON vs. EXP: 16.0% vs. 36.1%, respectively, p < 0.001) in the rumen of cattle fed the extruded compound feed was increased. Conclusion: These results revealed that the optimal ratio of peanut vine: corn: urea was 65:30:5, which was the most effective and economical formulation. The extruded compound feed is a promising feedstuff, which could effectively improve rumen fermentation and growth performance in fattening cattle.