Fermentation Quality of Herbal Tea Residue and its Application in Fattening Cattle Under Heat Stress

Background: Herbal tea residue (HTR) is generally considered to be the waste of herbal tea beverage production while it still retains rich nutrients and active substances. The main aim of the present study was to investigate the effect of fermentation technology on improving the quality of HTRs, and focus on the fermented HTR-induced alleviation of summer heat stress in fattening cattle.Results: In this study, the waste HTR was fermented and then fed to a total of 45 fattening cattles that were divided into 3 groups (fermented HTR replaced 0%, 15%, 30% of Pennisetum purpureum respectively), and the feeding experiment was lasted for 40 days. 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. In addition, we studied the fecal microorganisms composition of 6 fattening cattles in each group and found 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. Conclusions: we suggested that 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.