Fermentation quality of herbal tea residue and its application in fattening cattle under heat stress

Herbal tea residue (HTR) is generally considered to be the waste of herbal tea beverage production while it still remains rich nutrients and active substances. In this study, the waste HTR was fermented with oat grass and fed to fattening cattle to alleviate heat stress in summer. The physiological indexes, growth performance and fecal microorganisms of fattening cattle were evaluated and results showed that fermented HTR could effectively reduce the respiratory rate and rectal temperature of fattening cattle under heat stress, increase the daily feed intake and daily gain, and improve the antioxidant content and blood immune index. We also found that fermented HTR significantly changed the composition of fecal microorganisms and increased microbial diversity, and correlation analysis suggested that the bacteria were closely related to fecal SCFA levels of fattening cattle under heat stress. In conclusion, 30% of fermented HTR can help maintain health of fattening cattle and alleviate the heat stress of fattening cattle by the change of intestine microorganisms.