Effects Of Tea Residue Addition On Nutritional Quality And Microbial Diversity Of Alfalfa And Sweet Sorghu

As tea has become one of the most consumed beverage types in the world,the area under cultivation of tea has also increased rapidly.China is the world’s largest tea producer,producing nearly 3.3 million tons of tea and planting nearly 3.1 million hectares in 2022.Therefore,a large amount of tea residue is produced in the process of tea processing and utilization.Tea residue is usually used as compost substrate or landfill directly,resulting in resource waste and environmental pollution.Tea residue has a high crude protein content.It is found that tea residue can be used as a potential protein supplement for silage.Tea residue is a high quality supplement for single stomach animal feed.However,the effect of tea residue addition on the quality of forage silage is still unclear.In order to expand the range of feed utilization of tea residue,different proportions of different processing technologies(green tea,black tea,white tea,Pu erh raw tea,Pu erh ripe tea tea residue)were added to Medicago sativa L.and Sorghum bicolor(L.)Moench.By measuring the nutritional quality,fermentation quality,antioxidant capacity and microbial community structure,the effects of tea residue addition on the nutrition and fermentation quality of silage herbage were clarified,so as to screen out the types and amounts of tea residue that can improve the nutrition and fermentation quality of herbage and provide theoretical basis for the forage utilization of tea residue.The main research results are as follows:(1)Compared with the treatment without tea residue(ACK),the contents of total nitrogen(TN),crude protein(CP)and true protein(TP)of alfalfa except white tea residue were significantly increased by adding 5% and 10% tea residue,and the protein content of silage was increased with the increase of tea residue addition;Adding 10% tea residue reduced the content of ammonia nitrogen(AN)in herbage.Non-protein nitrogen(NPN)content did not change significantly.Except for Pu ’er ripe tea residue,the DPPH radical scavenging rate,ABTS radical scavenging rate and total antioxidant capacity of other tea residue addition groups were significantly higher than those of ACK.The contents of lactic acid(LA)and acetic acid(AA)in alfalfa silage were decreased by adding different processing technology and proportion of tea residue,while the p H was slightly decreased.The microbial diversity and richness of all tea residue treatment groups were lower than ACK.The main dominant bacteria groups are Enterococcus,Kosakonia,Lactobacillus,Weissella,etc.In conclusion,the nutritional quality(nitrogen component)and antioxidant capacity of alfalfa were significantly improved by tea residue addition,and the gain effect was increased with the increase of tea residue addition,but the effect on fermentation quality was not obvious.Based on the analysis of nutritional quality and antioxidant capacity of tea residue addition groups,green tea tea residue addition effect was the best,followed by black tea and raw tea,white tea and ripe tea treatment group was the worst.(2)Compared with the treatment without tea residue(TCK),the contents of TN,CP and TP of sweet sorghum silage were significantly increased and the contents of AN were decreased by adding tea residue with different processing technology and proportion.The protein content of grass silage was increased with the increase of tea residue addition,while the NPN content was slightly increased.Except for ripe tea residue,the DPPH radical scavenging rate,ABTS radical scavenging rate and total antioxidant capacity of other tea residue addition groups were significantly higher than those of TCK.The p H value of sweet sorghum silage was decreased and the contents of LA and AA were increased by different processing technology and tea residue addition ratio.The microbial diversity and richness of all tea residue treatment groups were lower than that of TCK.The dominant bacteria groups are Lactiplantibacillus,Enterococcus,Pantoea,etc.In conclusion,the nutritional quality(nitrogen component),fermentation quality and antioxidant capacity of sweet sorghum were significantly improved by tea residue addition,and the gain effect increased with the increase of tea residue addition level.Based on the analysis of silage quality of tea residue addition treatment groups,green tea residue had the best effect on improving protein content,Puerh tea tea residue had the best effect on improving fermentation quality and nutritional quality,followed by black tea and raw tea,white tea and ripe tea treatment groups had the worst quality.In conclusion,tea residue addition can improve the silage quality of alfalfa and sweet sorghum,and the effect increases with the increase of the addition amount.Green tea residue added to alfalfa and green tea and Pu ’er tea residue added to sweet sorghum have the best effect,which has the potential as the additives of silage herbage.