| Feed additives play an irreplaceable role in improving the growth performance of livestock and poultry,disease resistance,livestock product quality and farming efficiency.Currently,traditional antibiotic-based feed additives are being phased out in the context of "no antibiotics".Therefore,the development of green and efficient plant extracts as feed additives is of great interest.To investigate the feasibility of the plant extract tea saponin as a feed additive for beef cattle,this experiment used the plant extract tea saponin as test material to study the effect of different levels of tea saponin added to feed on the growth performance,nutrient digestion,serum indices,rumen digestive enzyme activity and fermentation parameters,rumen flora numbers and microbiota of Qinchuan beef cattle.In this study,16well-developed cattle of similar weight(250±10kg)and 14 months of age of a new strain of Qinchuan beef cattle for meat(hereafter referred to as "Qinchuan beef cattle")were randomly divided into four groups of four cattle each.Each group was fed 0 g/d(control group),10 g/d(LT group),20 g/d(MT group)and 30 g/d(HT group)of tea saponin in the basal diet.The main findings of the study were as follows:1.Compared with the control group,the average daily gain(ADG)of test cattle in all three test groups increased significantly(P<0.05)and the feed-to-weight ratio(F/G)decreased significantly(P<0.05);the apparent digestibility of dry matter,neutral detergent fibre and acid detergent fibre of test cattle in the MT and HT groups was significantly higher than that of the control group(P<0.05);the growth in abdominal girth of test cattle in the MT group was significantly higher than that of Compared with the control group,serum urea(UN)levels were significantly lower in all three test groups(P<0.05),by 20.49%,23.60% and 25.15%,respectively,and serum aspartate aminotransferase(AST)and alanine aminotransferase(ALT)activities were significantly lower in the MT group(P<0.05).The economic efficiency analysis showed that the MT group had the largest gross profit of 1279.66 RMB/each,which was 173.50 RMB/each higher than that of the control group.2.The activities of protease,α-amylase and xylanase in the rumen of the test cattle in all test groups were not significantly different(P>0.05),compared with the control group,the activity of pectinase in the rumen of the test cattle in the HT group was significantly lower(P<0.05),and the activity of cellulase in the rumen of the test cattle in the LT and MT groups was significantly higher(P<0.05),by 14.20% and 6.25% respectively Compared to the control group,the number of protozoa in the rumen of the test cattle was significantly reduced(P<0.05)by 54.06%,58.26% and 55.11% in the three test groups,while the number of fungi and white rumen cocci in the rumen of the test cattle was significantly increased(P<0.05)in the MT and HT groups.3.Compared with the control group,the microbial protein content of the test cattle in the LT and MT groups was significantly higher(P<0.05)by 25.43% and 19.73%,respectively;the total volatile fatty acid and propionic acid content of the test cattle in the LT group was significantly higher than that of the control group(P<0.05);in all groups,Bacteroidetes and Firmicutes were the dominant bacterial phylum in the rumen of Qinchuan beef cattle,and Ascomycota and Neocallimastigomycota were the dominant fungal phylum in the rumen of Qinchuan beef cattle;the chao1 index and faith＿pd index of bacteria in the MT group were significantly lower compared with the control group(P< 0.05);compared with the control group,the relative abundance of Proteobacteria in the HT group increased significantly(P<0.05),Actinobacteria in the LT group increased significantly(P<0.05),and the relative abundance of Bacteroides in the three experimental groups decreased significantly(P< 0.05),Ascomycota in the MT group(P<0.05),Saccharomyces in the LT and MT groups(P<0.05),and Aspergillus in the LT group(P<0.05);The PICRUSt functional prediction results showed that the abundance of genes for the Xenobiotics biodegradation and metabolism and glycolysis III pathways were significantly higher in the LT and MT groups than in the control group(P<0.05).In conclusion,the addition of tea saponin to the diet can increase the number of bacteria associated with fibre breakdown in the rumen and improve digestive enzyme activity,change rumen fermentation parameters,regulate rumen microbiota,improve the apparent digestibility and performance of Qinchuan beef cattle,under the conditions of this study,taking into account the economic benefits,the optimum concentration of tea saponin added to 20 g/d,providing a theoretical basis for the development and use of tea saponin as a green and efficient feed additive... |
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