Effects of adding pineapple residue on silage fermentation quality and protein fractions of Broussonetia papyrifera leaves

The leaves of Broussonetia papyrifera are rich in protein, amino acids, vitamins and trace elements. They have great development potential as unconventional protein resources. To promote the further utilization of B. papyrifera as feed, this experiment was carried out to evaluate the effects of adding pineapple residue on fermentation quality and protein fractions of silages of B. papyrifera leaves using the Cornell Net Carbohydrate and Protein System(CNCPS). The experiment wed single factor method designed with different addition rates(0, 5%, 10%, 15% and 20% fresh weight of pineapple residue) and the silages were kept for 60 d at room temperature. The results showed that B. papyrifera leaves contained higher buffering capacity and a few water soluble carbohydrates, the silage without pineapple residue had poor quality with a high pH beyond 5.0. As the addition rate of pineapple residue was increased, the silage pH was significantly reduced and the lactic acid content significantly increased. Compared with the control, the silage added with 20% pineapple residue had the best fermentation quality. After ensiling, about 30% true protein in the leaves was converted to fraction A. The contents of fraction A and fraction C were higher than those in fresh leaves, while the fraction B3content was lower than that before ensiling. Because pineapple residue contains higher non-protein nitrogen than B. papyrifera leaves, adding pineapple residue increased fraction A content in the adding ensiled forage. Adding pineapple residue can improve silage fermentation quality of B. papyrifera leaves. But the adding level must be appropriate, otherwise it can reduce the silage nutritional value.