Prediction Equations And Improving Methods Of Available Energy In Barley Fed To Pigs

Five experiments were conducted to determine the chemical compostion,available energy and ileal digestibility of anmino acid of barley samples in growing pigs and estabolish prediction equations to predict their available energy as well as the digestibility of amino acids.In addition,partial dehulling of barley or a nonstarch polysaccharide(NSP)enzyme adding to barley were conducted to measure the available energy and nutrient digestibility according to the high content of fibrous constituents of barley.In Exp.1,22 barley samples were collected including 18 domestic barley samples and 4 foreign barley samples.The chemical compostion of barley samples was analyzed.The results showed that different sources of barley had significant variation in chemical contents.The study showed that the coefficient variation of crude protein(CP),ether extract(EE),ash and phosphorous were were between 11%and 13%.The content of neutral detergent fiber(NDF)in barley ranged from 16.12%to 36.87%with the coefficient variation of 26.68%,while the content of acid detergent fiber(ADF)in barley ranged from 3.94%to 9.67%with the coefficient variation of 24.87%.In Exp.2,the digestible energy(DE)and metabolisable energy(ME)content of barley were determined and prediction equations were established based on their chemical compostion using the method of direct and total collection of feces and urine.Ninteen barley samples including fifteen native barley varieties and four foreign barley samples were collected.57 crossbred barrows with an initial bady weight of 33.5 ± 5.4 kg were used in the experiment conducted over 2 consecutive periods(n = 6)according to a completely randomized design.The results showed that the DE contents ranged from 13.64 to 15.49 MJ/kg DM and averaged in 14.67 MJ/kg DM.The ME contents ranged from]3.43 to 15.21 MJ/kg DM(Mean 14.37 MJ/kg DM).The best prediction equations were DE(MJ/kg DM)= 2.901-0.296 x ADF(%)+ 0.018 x NDF(%)+0.708 x GE(MJ/kg DM),R2 = 0.92 and ME(MJ/kg DM)= 6.442-0.299×ADF(%)+ 0.022×NDF(%)+ 0.498×GE(MJ/kg DM),R2 = 0.92.Moreover,the ME was highly correlative with DE(R2 =0.96).In Exp-3,the apparent(AID)and standardized(SID)ileal digestibility of amino acids were determined in 9 barley samples.Ten barrows(average initial body weight = 30.9 ± 1.8 kg)fitted with a sample T-cannula were assign to a 6× 10 Youden squar designs with six periods and ten diets comprising one nitrogen-free diet and nine barley test diets.The nitrogen-free diet was used to determine the endogenous losses of nitrogen.Chromic oxide was used as an indigestible marker.There were significant differences in the AID and SID of CP and most amino acids among different barley samples(P<0.05).Ash was a good indicator to predict AA digestibility among prediction equations.In Exp.4,two barley samples with different fiberous contents were partial dehulled.Thirty crossbreed barrows(initial BW of 31.5 ± 3.2 kg)were allotted to 1 of 5 treatments(6 pens per treatment and 1 pig per pen)according to a completely randomized design with a corn group,high fiber barley group(HF)and low fiber barley group(LF)as well as dehulled high fiber barley group(DHF)and dehulled low fiber barley group(DLF).The experiment period lasted 15d with an adjustment period of 10d followed by a 5-d collection period.Results showed that partial dehulling decreased the fiber content about 40%and increased the CP and EE contents of barley about 14%and 6%,respectively.The daily GE of feces in DHF barley was significantly lower than that in HF barley(P<0.01)and had no differences with the other groups.The DE and ME values of barley samples were significantly increased due to dehulling(P<0.05).The DE and ME values of DLF were increased about 8%than DHF(P<0.05)and had no differences with those values of corn.Meanwhile,the digestibilities of gross energy(GE),organic matter(OM)and fiber constituent in barleys were enhanced(P<0.05).In Exp.5,thirty crossbreed barrows(initial BW of 32.2 ± 2.8 kg)were allotted to one of five treatments(6 pens per treatment and 1 pig per pen)according to a completely randomized design with a corn group,high fiber barley group(HF)and low fiber barley group(LF)as well as high fiber barley supplemented with NSP enzymes group(HFE)and low fiber barley supplemented with NSP enzymes group(LFE).The experiment period lasted 15d with an adjustment period of 10d followed by a 5-d collection period.The results showed that the daily loss of GE and N in feces was lesser for pigs fed HFE diet than for those fed unsupplemented(P<0.05).The DE and ME as well as the digestibilities of GE,OM,CP,NDF and ADF were increased in HFE diet(P<0.05)while had no effects to LF diet.To summarize,the sources of barley can affect the chemical characteristics,available energy value and ileal digestibility of amino acids.Prediction equations of available energy and ileal amino acids digestibility can provide accurate and real-time data for feed manufacturer.The Effects of removing hull of LF barley on energy conteny and nutrient digestibility were were superior to HF barley.The effects of NSP enzyme added to HF barley were superior to LF barley.Using the improvement methods distinctively will promote the reasonable and efficient usage of different barley varieties in feed industy.