Effect of maize straw additives on the nutritional quality and bacterial communities of ensiled forage rape for animal feed

Fating Yin1, 2, Zhibo Cheng1, and Fenghua Zhang1, 2*
The impact of forage rape (Brassica napus L.) with maize (Zea mays L.) straw addition on the changes of nutritional quality and bacterial community was investigated by using high-throughput sequencing analysis of the 16S rRNA. The six ensilage treatments were set based on different mass ratios of forage rape (S) and maize stalk (Y):S1 (forage rape:maize stalk 10:0), S7Y3 (7:3), S6Y4 (6:4), S5Y5 (5:5), S4Y6 (4:6), and S3Y7 (3:7). The results showed that compared with S1, the DM content of S7Y3, S6Y4, S5Y5, S4Y6 and S3Y7 increased by 10.71%, 16.02%, 22.56%, 24.37% and 30.19% after the maize straw addition, respectively. Contents of crude protein (CP), ether extracts (EE) and water-soluble carbohydrate (WSC) contents in S7Y3 were significantly higher than that of other maize straw additive treatments (P < 0.05), which were 11.11% DM, 4.54% DM and 12.50% DM, respectively. On the 60th day of fermentation, the lowest pH value was found in S7Y3, which was 3.56. The V-score of each treatment were above 80. Bacterial Shannon and Chao indices were highest in S7Y3. The dominant bacterial phyla across all silage samples were Firmicutes, Proteobacteria, Cyanobacteria and Actinobacteria. The dominant genera are Lactobacillus and Weissella. Redundancy analysis (RDA) suggested that DM, CP, EE and WSC are the main factors in shaping bacterial communities. This study demonstrated that forage rapewith maize straw addition can affect the nutritional quality and bacterial community of silage, and the best mixing ratio of maize straw and forage rape ensilage is 7:3.
Keywords: Bacterial community, ensilage quality, forage rape, maize straw additives.
1Shihezi University, Agricultural College, Beiyuan Campus 832003, Shihezi, Xinjiang, China. 2Shihezi University, Agricultural College, Key Laboratory of Oasis Eco-agriculture, Beiyuan Campus 832003, Shihezi, Xinjiang, China. *Corresponding author (zhangfenghua6088@126.com).