Effects of Different Additives on the Chemical Composition, Fermentation Profile, In Vitro and In Situ Digestibility of Paper mulberry Silage

Paper mulberry <i>(Broussonetia papyrifera</i>) plants are served as a local roughage in China, and they are mostly processed as silage for ruminants. This study aimed to explore the effects of different silage additives on the chemical composition, fermentation profile, as well as the in vitro and in situ digestibility of paper mulberry (PM) silage. Four groups consisting of PM silage, three with additives and one without any additives as the control group (CON), were established. The three experimental groups with additives were set up as follows: CON with 5 × 10⁶ CFU per gram of fresh PM weight of lactic acid bacteria (<i>Lactobacillus plantarum</i>) (LAB); CON with 3% fresh PM weight of molasses (MOL) added to the PM silage; and CON with both LAB and MOL added (LM). After 45 days of ensiling at 20 °C, all of the PM treatment groups increased their ash content and decreased their water-soluble carbohydrate content (<i>p</i> < 0.05). Meanwhile, the pH and NH₃-N content of the PM silage were lower in the additive treatment groups than in the CON group (<i>p</i> < 0.05). Lactic acid in the LM group was the highest (<i>p</i> < 0.05) among the four groups, and trace amounts of butyric acid was detected only in the CON group. In vitro dry matter digestibility was similar among all groups. Results of the in situ experiment found that the effective digestibility of the PM silage dry matter, as well as the acid detergent fiber digestibility was higher in the LM group than in the CON group (<i>p</i> < 0.05). In conclusion, the addition of LAB, MOL, and their combination can improve PM silage fermentation and improve the in situ digestibility of dry matter and acid detergent fiber; however they do not affect in the vitro digestibility of PM silage.