Effects of different ratios of licorice stems and leaves with whole-plant corn mixed silage on in vitro fermentation and rumen microbiota in sheep

GAO Qifeng; SUN Yuliang; LIU Haonan; TANG Limin; LIU Fangpeng; JIA Chunying; YU Houjun; JIANG Tao

doi:10.13557/j.cnki.issn1002-2813.2025.14.001

Abstract：The experiment aimed to investigate the effects of mixed silage with different ratios of licorice stems and leaves to whole-plant corn on the in vitro fermentation parameters,nutrient degradation rate,and rumen microbiota in sheep.Five mixed silage groups with licorice-to-corn ratios of 7∶3(group G7Y3),6∶4(group G6Y4),5∶5(group G5Y5),4∶6(group G4Y6),and 3∶7(group G3Y7)were used as substrates for in vitro fermentation.Gas production parameters,fermentation characteristics,rumen microbial composition,and nutrient degradation rates were measured over 72 hours.The results showed that after in vitro fermentation for three to 36 hours,the gas production of group G5Y5 was the highest,significantly higher than that of groups G7Y3 and G6Y4(P＜0.05).At 72 hours of in vitro fermentation,the pH value of group G5Y5 was significantly lower than that of the other groups(P＜0.05).The content of total volatile fatty acids in groups G4Y6,G5Y5 and G3Y7 was significantly higher than those in groups G6Y4 and G7Y3(P＜0.05).The content of acetic acid in group G5Y5 was significantly higher than that in other groups(P＜0.05).The concentrations of propionic acid and butyric acid in group G4Y6 were significantly higher than those in other groups(P＜0.05).The dry matter degradation rate,acid detergent fiber degradation rate,and neutral detergent fiber degradation rate of group G4Y6 were significantly higher than those of the other groups(P＜0.05).The Firmicutes and Bacteroidetes were the dominant bacterial phyla.At 12 hours of in vitro fermentation,the abundance of the Firmicutes in group G4Y6 was the highest,significantly higher than that of the group G3Y7(P＜0.05).The abundance of Bacteroidetes in group G3Y7 was the highest,significantly higher than that in other groups(P＜0.05).The dominant bacterial genera were the Christensenellaceae R-7 group,Prevotella and Rikenellaceae RC9 gut group.At 12 hours of in vitro fermentation,the abundance of Christensenellaceae R-7 group in group G6Y4 was the highest,significantly higher than that of groups G4Y6 and G3Y7(P＜0.05).The abundance of Prevotella in group G3Y7 was significantly higher than that in other groups(P＜0.05).The study indicates that when the mixture ratio of licorice stems and leaves to whole-plant corn is 4∶6,the degradation rate of nutrients in vitro is relatively high,and it has a significant impact on the in vitro fermentation parameters and rumen microbial community of sheep.However,the difference is not significant compared with the mixture ratio of 5∶5.Based on the maximum utilization of licorice stems and leaves,it is proposed to use a mixture ratio of 5∶5 for silage.