The Ruminal Degradation Characteristics Of Stevia Granules And Application In The Ration Of Dairy Cows

This experiment used rumen nylon bag technique combined with feeding experiments.The purpose of this experiment was to investigate the degradation characteristics of Stevia granules in the rumen of lactating dairy cows and the effects of different levels of Stevia granules in diets on the production performance,economic benefits and blood biochemical indexes of lactating dairy cows.In order to provide references when making formulas for dairy cows.The main research contents and results are as follows:1.Studies on the nutritional components of Stevia granules and their degradability in rumen of dairy cows.In this experiment,4 dairy cows(adult Holstein cows)with permanent rumen fistula were selected,whose body weight was(600±30)kg,lactation volume was(16.4±0.7)kg and physiological status was similar.The dynamic degradation rate of nutritional components(DM,CP,NDF,ADF)in rumen was evaluated by nylon belt method.The results showed that the crude protein(CP)content was 16.74%,the neutral detergent fiber(NDF)content was 50.58%,the acidic detergent fiber(ADF)content was 38.06%and the crude fat(EE)content was 2.23%;When the rumen velocity k=0.046/h,the effective degradation rate of dry matter(DM)reached 30.78%,the effective degradation rate of crude protein(CP)reached 40.28%,the effective degradation rate of neutral washing fiber(NDF)reached 26.78%,and the effective degradation rate of acidic washing fiber(ADF)reached 22.81%.2.Effect of stevia granules on production performance of lactating cowsIn this experiment,24 cattle with similar lactation days(135.96±25.98)d,parity(1?2)times,milk yield(29.78±5.42)kg and physiological status were randomly divided into four groups,6 cattle in each group.According to Chinese Dairy Cattle Feeding Standard(2004)Nutritional Requirements and Feeding Standard Configuration of Dairy Cattle,Stevia granules were added on the basis of dry matter:0%,3.5%,5.5%and 7.5%,of which 0%was the control group.The experiment was continued up 47 d,including 7 d of adaptation period and 40 d of experiment period.The results of feeding test showed that when lactating cows added 3.5%and 7.5%of stevia granules to their diets,their dry matter intake(DMI)was significantly increased compared with the control group(P<0.05).There was no significant effect on milk composition and rumen fermentation parameters of lactating cows(P>0.05).When the price of raw milk was 4.00 yuan/kg,the economic benefit was best when 7.5%stevia granules were added to lactating cows.3.Effect of Stevia granules on serum biochemical indexes of lactating dairy cowsThe experimental designs are as the same with the second experiment.The results showed that after adding different levels of stevia granules to the diets of lactating cows,there was no significant effect on serum enzyme index of dairy cows compared with control group(P>0.05).Compared with the control group,there is an increasing trend of GGT and LDH.There was no significant effect on serum immune index between the experimental group and the control group(P>0.05).There was no significant effect on other biochemical indexes(P>0.05).Conclusion:In summary,in the development and utilization of unconventional feed,stevia granules can effectively degrade in rumen.On the premise of not affecting the physiological state of lactating cows,the economic benefit of adding 7.5%stevia granules to the diet was the best.