Feasibility Research Of Tea Residue In Substitution Of Alfalfa For Goats

The development and utilization of nonconventional alternatives of high-quality forage,such as alfalfa hay,are crucial for diversify source of goat feed.China produces a large amount of tea residue,which has a high crude protein content and a similar nutritional value to alfalfa hay.This preliminary indication suggests that tea residue may be a potential alternative for alfalfa in goat feed.The objective of this study was to investigate the feasibility of substituting alfalfa with tea residue through in vitro ruminal fermentation and goat feeding trials.The findings may be beneficial to the further application of tea residue in goat feed.The paper consists 3 trials.Experiment 1.In Vitro Ruminal Fermentation Characteristics of tea residue and Alfalfa HayFour Guizhou black goat were selected as rumen fluid donors.Twenty-four sets of ANKOM system gas production bottles were randomly divided into 3 groups with eight replicates per group and one gas production bottle per replicate.The in vitro fermentation substrate contains 4 grams of alfalfa or tea residue samples,and 8 blank bottles were also set.Gas production,rumen fermentation parameters and microbial community were measured.The approximate nutrients of tea residue were（%DM）:GE 19.62 MJ/kg,CP 23.17%,NDF67.8%,OM 95.82%.The approximate nutrients of alfalfa was（%DM）:GE 16.66 MJ/kg,CP16.07%,NDF 33.67%,OM 87.82%.Total gas production of alfalfa was significantly higher than tea residue from 4 to 48 hours（P<0.05）.The final p H of the fermentation broth in the tea residue group was lower than that in the alfalfa group（P<0.05）.The in vitro dry matter degradation in tea residue group was 51.61%higher than alfalfa（P<0.05）.The NH₃-N level in the alfalfa group was 112.82%higher than tea residue（P<0.05）.The MCP content in the alfalfa group was significantly higher than tea residue（P<0.05）.Digestible organic matter,organic matter degradation rate,and metabolic energy,as calculated from the 24-hour gas production,were significantly higher in the alfalfa group than tea residue（P<0.05）.Tea residue had a lower propionic acid,isobutyric acid,butyric acid,isovaleric acid and valeric acid than alfalfa（P<0.05）.Xylanase activity was significantly higher in the alfalfa group than tea residue（P<0.05）.Abundance of Bacteroidetes,Spirochetes and Proteobacteria in tea residue was significantly higher than alfalfa（P<0.05）.The abundance of Firmicutes and Euryarchaea were significantly lower in tea residue group than alfalfa（P<0.05）.Experiment 2.Effect of Varying Replacement Level of Alfalfa Hay by Tea Residue on in Vitro Rumen Fermentation of GoatsFour healthy Guizhou local meat goat（BW:34.72±1.55 kg）were selected as rumen fluid donors.The fermentation substrate consisted of tea residue substituted for alfalfa at different ratios in the diets:T0（no substitution）,T1（33.3%substitution of alfalfa）,T2（66.7%substitution of alfalfa）,and T3（100%substitution of alfalfa）.Alfalfa stands for 10%in the control diet（T0）.In vitro gas production analysis were conducted following the procedure in Experiment 1.From 10 to 48 hours,GP level in T1 group was significantly higher than T3group（P<0.05）.At the end of fermentation（72 h）,gas production in T1 group was significantly higher than T0 and T3 groups（P<0.05）.The p H of fermentation broth in the T0and T3 groups was significantly higher than T2 group（P<0.05）.The NH₃-N level in T0 and T2 groups was significantly higher than T1 and T3 groups（P<0.05）.The OMD,ME,and DOM in T1 group were significantly higher than T3 group（P<0.05）.The level of isobutyric acid was significantly higher in the T0 and T2 groups than T1 and T3 groups（P<0.05）.The concentration of butyric acid was significantly higher in T2 group than T1 and T3 groups.The level of isovaleric acid was significantly higher in T2 group than in T1 and T3 groups.Valeric acid profiles was significantly higher in T2 group than in T1 and T3 groups.The ratio of acetic acid/propionic acid was significantly higher in T0 group than in T1,T2,and T3 groups（P<0.05）.The methane profiles was significantly higher in T0 and T2 groups than in T3 group（P<0.05）.The remaining indicators showed no significant differences.Experiment 3.Effect of Tea Residue in Substitution of Alfalfa Hay Plasma Metabolites,Rumen Parameters,and Muscle Amino Acid Levels in GoatsForty-four healthy Guizhou Black goats（18.49±3.03 kg）were selected and were randomly divided into 4 groups.The goats were received one of diets,used as fermentation substrates,in Experiment 2.The trial lasted for 75 days,including a 15-day pre-feeding period and a 60-day formal period.The growth performance,plasma parameters,rumen parameters,and muscle amino acid profiles were measured.There were no significant differences in growth performance indexes among the 4 groups of goats（P>0.05）.The GE digestibility of T1 was significantly higher than T0,T2,and T3（P<0.05）.The crude protein digestibility of T1 and T2 was significantly higher than T0 and T3（P<0.05）.The NDF digestibility of T1 was significantly higher than T0 and T2（P<0.05）.The digestibility of ADF in T1 and T3 was significantly higher than T0 and T2（P<0.05）.The digestibility of organic matter in T1 was significantly higher than other 3 groups（P<0.05）.Total protein concentration in T0 was significantly lower than T1,T2,and T3（P<0.05）.The urea concentration in T3 was significantly lower than T1,T2,and T0（P<0.05）.The albumin content was significantly higher in T2 than in T0（P<0.05）.LDL-C was significantly higher in T2 than the remaining 3groups（P<0.05）.The replacement of tea residue did not cause any significant differences in rumen ammonia nitrogen（NH₃-N）and microbial protein（MCP）levels（P>0.05）.The p H of T0 and T2 was significantly higher than T1（P<0.05）.Theβ-Glucosidase activity was significantly higher in the T0 group than in the T1 and T3 groups（P<0.05）.Total volatile fatty acids,acetic acid content,and methane production were significantly higher in T1 than in other 3 groups（P<0.05）.The abundance of Proteobacteria in rumen fluid was significantly higher in T1,T2,and T3 than T0（P<0.05）.The abundance of Prevotella was significantly higher in T1 and T3 than T0（P<0.05）.The abundance of the Selenomonas in T3 was significantly higher than that in T2 and T0（P<0.05）.The content of citrulline in T1 and T2was significantly higher than T0（P<0.05）.The content of muscle glycine decreased in the order of T0,T1,T2,and T3 groups,with significant differences between them（P<0.05）.However,there were no significant differences in the remaining amino acids among the 4groups（P>0.05）.It is concluded that tea residue can be used as the alternative of alfalfa for goats,however,it can not completely replace alfalfa.An approximate replacing level can enhance rumen fermentation and has no adverse effect on blood metabolites and rumen health.Overall,when alfalfa stand for 10%in the diet,66.7%replacing level can be applicated in the practice.