Study On Nutritional Value Evaluation Of Industrial Hemp Byproducts And Its Application In Dairy Cows

Along with the development of our country’s livestock industry,the shortage of feed can not meet the increasing demand of livestock,and the high feed cost reduces the benefit of breeding,so there is an urgent need to find high-quality and cheap feed resources.Industrial hemp is an annual herb belonging to the genus Cannabis in the Cannabis family.It has a variety of production purposes,such as seeds for oil extraction,stems for fiber production and flowers for drug extraction.Different processing methods produce different byproducts,such as seed meal,hemp leaf and extraction residues.At the same time,with the growing area and output of industrial hemp increasin g year by year,the processing of byproducts of industrial hemp has become a difficult problem.Therefore,the purpose of this experiment was to compare the nutritional value of 9 kinds of industrial hemp byproducts and 4 kinds of conventional feeds,so as to provide scientific basis for rational utilization of industrial hemp byproduct.And this trial was designed to investigate the effects of industrial hemp ethanol extraction byproduct（IHEEB）and Chinese wildrye hay replacement of alfalfa hay on diet,nutrient digestibility,lactation performance,ruminal fermentation,plasma metabolites,bacterial community and economic benefit in Holstein dairy cows.It provides a theoretical basis for the application of IHEEB to replace alfalfa hay in dairy production,and has important significance for alleviating the shortage of high quality forage resources and improving the economic benefi ts of dairy farming.Experiment 1:Comparative study on nutritional value of industrial hemp by-products and conventional feedIn this experiment,9 kinds of industrial hemp byproducts and 4 kinds of conventional feeds were determined conventional nutrient composition by conventional chemical analysis method.The carbohydrate and protein components were analyzed by the Cornell Net Carbohydrate and Protein System（CNCPS）method.Rumen in situ degradation parameters were determined by in situ nylon bag method.The improved three-step in vitro method was used to evaluate intestinal digestibility.Digestible energy values were estimated from the National Academy of Sciences,Engineering and Medical Sciences（NASEM）model.The results show that:（1）The nutritional composition of different industrial hemp byproducts and conventional feed s is very different.The crude protein（CP）contents of the of Zhaozhou industrial hemp ethanol extraction byproduct,Daxing’anling industrial hemp ethanol extraction byproduct-B,industrial hemp distillation byproduct,industrial hemp leaf and industrial hemp mixture were significantly higher than alfalfa hay,Daxing’anling industrial hemp ethanol extraction byproduct-A and industrial hemp stalk（P<0.05）.The CP content of industrial hemp oil filter residue and soybean meal was significantly higher than that of industrial hemp seed meal（P<0.05）.The contents of neutral detergent fiber（NDF）and acid detergent fiber（ADF）of three kinds of industrial hemp ethanol extraction byproducts,industrial hemp distillation byproduct,industrial hemp lea f and industrial hemp mixture were lower than those of corn straw and alfalfa hay（P<0.05）.（2）The non-protein nitrogen（PA）content of industrial hemp seed meal was significantly higher than that of soybean meal but lower than that of industrial hemp oil filter residue（P<0.05）.The contents of medium rate degraded protein（PB₂）and unavailable nitrogen（PC）in industrial hemp seed meal were significantly higher than those of soybean meal（P<0.05）.The content of slow rate degraded protein（PB₃）in three kinds of industrial hemp ethanol extraction byproducts and industrial hemp leaf had no significant difference compared with Chinese wildrye hay（P>0.05）,but was significantly higher than that of corn straw and alfalfa hay（P<0.05）.Compared with corn straw and alfalfa hay,there was no significant difference in the rapidly degraded carbohydrate（CA）content of Zhaozhou industrial hemp ethanol extraction byproduct（P>0.05）.The content of medium-speed degraded carbohydrate（CB₁）of Zhaozhou industrial hemp ethanol extraction byproduct,Daxing’anling industrial hemp ethanol extraction byproduct-A and industrial hemp mixture was significantly lower than that of the three conventional roughages（P<0.05）.（3）The effective degradation rate（ED）of three kinds of industrial hemp ethanol extraction byproducts,industrial hemp distillation byproduct,industrial hemp leaf and industrial hemp mixture dry matter（DM）was significantly lower than that of alfalfa hay but higher than that of corn straw and Chinese wildrye hay（P<0.05）.The ED value of industrial hemp oil filter residue was significantly higher than that of industrial hemp seed meal and soybean meal（P<0.05）.The ED values of Zhaozhou industrial hemp ethanol extraction byproduct,Daxing’anling industrial hemp ethanol extraction byproduct-A,industrial hemp distillation byproduct,industrial hemp stalk and leaf CP were significantly lower than those of alfalfa hay but higher than those of corn straw and Chinese wildrye hay（P<0.05）.Therefore,their rumen undegradable protein（RUP）values were significantly higher than those of alfalfa hay but lower than those of corn straw and Chinese wildrye hay（P<0.05）.The ED value of CP in industrial hemp oil filter residue was significantly higher than that in industrial hemp seed meal and soybean meal（P<0.05）.The ED values of NDF of two kinds of Daxing’anling industrial hemp ethanol extraction byproducts,industrial hemp distillation byproduct and industrial hemp leaf were significantly higher than those of three kinds of conventional roughage（P<0.05）,while the ED values of NDF of Zhaozhou industrial hemp ethanol extraction byproduct were not significantly different fro m that of alfalfa hay（P<0.05）.（4）The total tract digested protein（TTDP）values of Zhaozhou industrial hemp ethanol extraction byproduct,industrial hemp distillation byproduct and industrial hemp stalk were significantly lower than those of the three conventional roughages（P<0.05）,but were significantly higher than those of the two Daxing’anling industrial hemp ethanol extract byproducts,industrial hemp leaf and industrial hemp mixture（P<0.05）.The TTDP content of industrial hemp oil filter residue was significantly higher than that of soybean meal（P<0.05）,but TTDP content of industrial hemp seed meal was significantly lower than that of them（P<0.05）.（5）The digestible energy（DE）values of industrial hemp distillation byproduct and alfalfa hay on dairy cows were not significantly different（P>0.05）,but significantly higher than those of three kinds of industrial hemp ethanol extract byproducts,industrial hemp stalk and industrial hemp mixture（P<0.05）.The DE values of three by-products of seed processing byproducts from high to low were industrial hemp oil filter residue,soybean meal and industrial hemp seed meal（P<0.05）.For beef cattle,the values of DE,metabolizable energy（ME）,net energy for maintenance（NEm）and net energy for weight gain（NEg）were the highest for industrial hemp distillation byproduct and industrial hemp mixture,and the lowest for Daxing’anling industrial hemp ethanol extraction byproduct-B.For the three seed processing byproducts,from the largest to the smallest,they we re industrial hemp oil filter residue,soybean meal and industrial hemp seed meal.Experiment 2:Effects of industrial hemp ethanol extraction byproduct（IHEEB）and Chinese wildrye hay replacement of alfalfa hay on diet,nutrient digestion,lactation performance,rumen fermentation,plasma indexes,bacterial community and economic benefit of dairy cowsNine healthy multiparity（parity=3）Holstein dairy cows with similar body weight（584±12.3kg）,lactation days（108±11.4 days）,and milk yield（30±1.93 kg）were used in this study.3×3repeated Latin square design was used for three periods of 21 d.During each experimental period,each group was fed one of the three treatment diets:（1）the unsubstituted basal experimental diet（0IHEEB）;（2）replacing 50%alfalfa hay in the basal diet with 6.0%IHEEB and 1.7%Chinese wildrye hay（6IHEEB）;（3）Replacing 100%alfalfa hay in the basal diet with 10.8%IHEEB and 4.3%l Chinese wildrye hay（11IHEEB）.Feed intake and milk yield was recorded,and TMR,refused diet,milk samples,rumen fluid,plasma and feces of cows were collected and measured.The results showed that:the content of physically effective NDF（pe NDF）in the 6IHEEB and 11IHEEB groups was significantly lower than that in the 0IHEEB group（P<0.05）.The ED values of DM,NDF and CP in the 11IHEEB group were significantly lower than those in the 0IHEEB and 6IHEEB groups（P<0.05）.The intake of CP and ADF decreased linearly（P<0.05）with the increasing proportion of IHEEB and Chinese wildrye hay replacement,but did not affect nutrient digestibility（P>0.05）.The somatic cell count in milk decreased linearly（P<0.05）and quadratic（P<0.05）with the increase of IHEEB and Chinese wildrye hay substitution ratio,and 6IHEEB and 11IHEEB groups were significantly lower than that in 0IHEEB group（P<0.05）.In rumen fermentation,the concentrations of total volatile fatty acids（TVFA）and butyric acid decreased linearly（P<0.05）,while the acetic acid concentration showed a linear trend of decrease（0.05<P<0.10）.In terms of plasma indexes,the plasma interleukin-1βconcentration was decreased linearly（P<0.05）and quadratic（P<0.05）,and the concentration in 6IHEEB and 11IHEEB groups was significantly lower than that in 0IHEEB group（P<0.05）.In terms of rumen bacterial community,the relative abundance of Bacteroidota,Fibrobacterota and Prevotellaceae showed a quadratic（P<0.05）increase.The relative abundance of Firmicutes showed a quadratic decreasing trend（0.05<P<0.10）.In terms of fecal bacterial community,as the substitution ratio increases,the relative abundance of Firmicutes,Lachnospiraceae,Monoglobaceae,Butyricicoccaceae,unclassified＿Clostridia,Butyricicoccaceae＿UCG＿009showedalinearincrease（P<0.05）and unclassified＿Clostridia＿UCG＿014 showed a linear decrease（P<0.05）.With the increase of substitution ratio,the relative abundance of unclassified＿Lachnospiraceae showed a linear increasing trend（0.05<P<0.10）.In terms of economic benefits,the cost of milk feed per kilogram was significantly reduced,from 2.25（?）/kg in the 0IHEEB group to 2.01（?）/kg in the 6IHEEB group and 1.81（?）/kg in the 11IHEEB group.It was concluded that:（1）The industrial hemp byproducts have high nutritional value and can be considered as unconventional feed resources to be added into the diet formula of dairy cows;（2）The industrial hemp ethanol extraction byproduct and Chinese wildrye hay replacement of alfalfa hay could change the diet grain size and rumen degradation characteristics,but did not affect nutrient digestibility of dairy cows,and it can improve milk composition,rumen fermentation and plasma immune indexes,change the composition of rumen and fecal ba cterial community of dairy cows,and reduce feeding costs.