The Degradation Kinetics And Intestinal Digestibility Of The Rumen Undegradable Protein Of Ten Commonly Used Feedstuffs In Beef Cattle And Evaluate Metabolizable Glucose Production

Two ruminally fistulated Xuanhan steers with healthy body and similar weight?450±5kg?as experiment animals.Using nylon bag technique to evaluated the degradation of dry matter?DM?,crude protein?CP?,neutral detergent fiber?NDF?,acid detergent fiber?ADF?and starch of ten feeds?energy feeds:corn and wheat bran,protein feeds:soybean meal,cottonseed meal and rapeseed cake,roughage feeds:alfalfa hay,sugarbeet pellet,grass hay,rice straw and corn cob?.A modified three-step in vitro procedure to estimate intestinal digestibility?Idg?of 16-h rumen undegradable protein?RUP?,intestinal digestibility of amino acid of RUP and intestinal digestibility crude protein?IDCP?of feeds.The nutrient compositions of feeds analyzed by feed proximat analysis and the Cornell net carbohydrate and protein system?CNCPS?.Combine the feeds compositions with the starch degradation of feeds in rumen to evaluate the value of metablizable glucose.The results showed that:1.Energy feed:The contents of carborhydrate?CHO?and carbohydrate A?CA?of corn were significantly higher than wheat bran?P<0.05?.The contents of protein A?PA?and protein B2?PB2?of wheat bran were significantly higher than corn,the contents of protein B1?PB1?and protein B3?PB3?of corn were significantly higher than wheat bran?P<0.05?.Protein feed:The contents of CHO and carbohydrate B2?CB2?of cottonseed meal was highest,followed by rapeseed cake,the lowest in soybean meal?P<0.05?.The content of carbohydrate C?CC?was highest in soybean meal,the highest proportion CC of CHO in rapeseed cake?P<0.05?.The content of PB1 of soybean meal was higher than cottonseed meal and rapeseed cake and the content of PB2 of cottonseed meal was higher than soybean meal and rapeseed cake.Roughage feed:The contents of CHO and CB1 were highest in corn cob,followed by grass gay,the lowest in alfalfa hay?P<0.05?.The content of CA of corn cob was significantly higher than other roughage feed?P<0.05?.The content CA,CB1,CB2,the proportion of CA of CHO,the proportion of CB1 of CHO and the proportion of CB2 of CHO were lowest in rice straw,the proportion of CC of CHO of rice straw was highest?P<0.05?.The PA and PB1 of alfalfa hay and sugarbeet pellet were higher than other three kinds of roughage feed.The content of PB2 of alfalfa hay was significantly higher than other roughage feed?P<0.05?.The content of CHO of roughage feeds highest,followed by energy feeds,the lowest in protein feeds.2.The disappearance rate of nutritive of feeds increased with increasing incubation time.Energy feed:The effective degradation?ED?of DM of energy feed corn was significantly higher than wheat bran?P<0.001?.The ED of CP,NDF and starch of wheat bran was higher than corn?P<0.01?.There was no significant observed for ED of ADF of corn and wheat bran?P=0.253?.The highest ED of DM,CP,NDF,ADF and starch were found in protein feed soybean meal,followed by cottonseed meal,the lowest in rapeseed cake?P<0.05?.The highest ED of DM,CP,ADF and starch were found in roughage feed sugarbeet pellet,followed by alfalfa hay,grass hay and rice straw,the lowest in corn cob?P<0.05?.The ED of NDF of sugarbeet pellet was highest,the lowest in rice straw?P<0.05?.3.The RDP,RUP and IDCP_{16-h RUP}content of energy feed wheat bran were significantly higher than corn?P<0.05?.The Idg of RUP of corn was higher than wheat bran?P<0.001?.The RDP,Idg of RUP and IDCP_{16-h RUP}content of protein feed soybean meal were highest,followed by cottonseed meal,the lowest in rapeseed cake?P<0.05?.The RDP and RUP content of roughage feed alfalfa hay was significantly higher than other roughage feeds?P<0.05?.The highest Idg of RUP and IDCP_{16-h RUP}content found in alfalfa hay,followed by sugarbeet pellet,grass hay and rice straw,the lowest in corn cob?P<0.05?.The RUP,RDP and IDCP_{16-h RUP}content of protein feed generally higher than energy feeds and roughage feeds.4.The Idg of essential amino acid arginine?Arg?,histidine?His?,lysine?Lys?,threonine?Thr?,valine?Val?and nonessential amino acid aspartic acid?Asp?,glycine?Gly?,proline?Pro?,serine?Ser?of wheat bran were significantly higher than corn?P<0.05?,the Idg of essential amino acid isoleucine?Ile?,leucine?Leu?,methionine?Met?,phenylalanine?Phe?and nonessential amino acid tyrosine?Tyr?,alanine?Ala?,cysteine?Cys?,glutamate?Glu?of corn were significantly higher than wheat bran?P<0.05?.The highest Idg of essential amino acid Arg,His,Ile,Leu,Lys,Met,Phe,Thr,Val and nonessential amino acid Tyr,Ala,Asp,Cys,Glu,Gly,Pro,Ser were found in protein feed soybean meal,followed by cottonseed meal,the lowest in rapeseed cake?P<0.001?.The highest Idg of total amino acid?TAA?was found in soybean meal.The Idg of essential amino acid Arg?His?Ile?Leu?Lys?Met?Phe?Thr?Val and nonessential amino acid Tyr?Ala?Asp?Cys?Glu?Gly?Pro?Ser of alfalfa hay were highest,followed by sugarbeet pellet,the lowest in corn cob except Tyr and Pro.The Idg of AA of protein feed generally higher than energy feeds and roughage feeds.5.Energy feed:The Idg of rumen bypass starch of corn was higher than wheat bran.Protein feed:The Idg of rumen bypass starch of soybean meal was significantly higher than cottonseed meal and rapeseed cake.The Idg of rumen bypass starch of alfalfa was highest.The values of MG of ten kinds of feedstuffs commonly used in beef cattle from high to low order is alfalfa hay,corn,grass hay,soybean meal,sugarbeet pellet,corn cob,cottonseed meal,rapeseed cake,rice straw and wheat bran.The values of MG were 158.78g/kg,143.46 g/kg,103.88 g/kg,99.16 g/kg,77.74 g/kg,71.77 g/kg,74.59 g/kg,70.13 g/kg,42.96 g/kg and 41.21g/kg,respectively.