Prediciton Of Metabolizable Energy And Metabolizable Protein In Feeds For Meat Sheep

In these series of research, meat sheep were used as animal models to study the prediction ofmetabolizable energy and metabolizable protein in feeds. The feasibility of the model using twelverations with different concentrate to forage ratio was detected by in vitro gas production experiment.And then prediction equations of metabolizable energy and metabolizable protein were developed by invivo and in situ experiment.The present research consists of three experiments which were listed asfollow.Experiment1: Prediction of in vitro organic matter digestibility and metabolizable energy in feedsfor meat sheepThe objectives of this experiment were to use the data of chemical composition to developprediction equations for in vitro organic matter digestibility and metabolizable energy of meat sheepfeeds with in vitro gas production technique. Using single-factor random design approach, twelve totalmixed ration with different concentrate to forage ratio,0:100,8:92,16:84,24:76,32:68,40:60,48:52,56:44,64:36,72:28,80:20and88:12were selected and three repetitions were measured by in vitro gasproduction technique for each ration. Chemical composition, in vitro organic matter digestibility and invitro metabolizable energy of each ration were determined and calculated by regression method. Theresults indicated that concentrate to forage ratio of TMR had significant effects on24h gas volume,potential gas production, gas-producing rate and pH, NH3-N VFA of fermentation fluid (P<0.05). Crudeprotein (CP) and neutral detergent fiber (NDF) in feed were significantly related to in vitro organicmatter digestibility (IVOMD)(P<0.01). Prediction equations for IVOMD using CP or NDF wereIVOMD (%)=28.845+2.022CP (%)(R²=0.932, n=12, P<0.001); IVOMD (%)=88.578-0.734NDF (%)(R²=0.921, n=12, P<0.001), respectively. CP, NDF, organic matter (OM) and24h in vitro gasproduction (GP24h) were significantly related to in vitro metabolizable energy (MEin vitro)(P<0.01).Prediction equations for ME using CP, NDF, OM or GP₂4hwere MEin vitro(MJ/kgDM)=-74.812+0.924OM (%)(R²=0.849, n=12, P<0.001); MEin vitro(MJ/kgDM)=3.866+0.285CP (%)(R²=0.931,n=12, P<0.001); MEin vitro(MJ/kgDM)=12.293-0.104NDF (%)(R²=0.921, n=12, P<0.001); MEin vitro(MJ/kgDM)=-2.677+0.241GP24h(mL/0.2kgDM)(R²=0.885, n=12, P <0.001).Experiment2: Prediction of metabolizable energy in feeds for Meat SheepTwelve crossbred rams (Dorper♂×Thin-tailed Han♀) fitted with permanent ruminal cannulas wereused in a uncompleted12×4Latin square arrangement, and fed with twelve different concentrate toforage ratio ration,0:100,8:92,16:84,24:76,32:68,40:60,48:52,56:44,64:36,72:28,80:20and88:12,respectively. Experiment comprised four periods, each period lasted for22d, and the first14d of eachexperiment were for ration adaption, with digestion and metabolism experiments and gas metabolic testduring d15to d22of each period. Chemical composition, nutrient digestibility and energyconcentrations of each ration were determined and calculated by regression method. The results showedthat, digestibility of dry matter (DM), organic matter (OM), gross energy (GE), and crude protein (CP)were positively related to OM, GE and CP (P<0.01), whereas they were negatively related to neutral detergent fiber (NDF)(P<0.01). Digestibility of NDF had an opposite relationship with those variables(P<0.05). There were positive relationship between concentrations of digestible energy (DE) ormetabolizable energy (ME) and feed OM, GE and CP (P<0.01), whereas they were negatively related(P<0.01) to NDF. Prediction equation of energy digestibility (ED) and ME based on chemicalcomposition were ED (%)=194.907-0.987NDF (%)-0.901OM (%)-0.603CP (%)(R²=0.966, n=12,P<0.001) and ME (MJ/kgDM)=50.245-0.136NDF (%)-0.394OM (%)-0.012CP (%)(R²=0.901, n=12,P<0.001), respectively. There were significant relationship between digestible nutrient and ME(P<0.01), and the equations developed was ME (MJ/kgDM)=-2.208+0.002DOM (g/kgDM)+0.988DE(g/kgDM)-0.013DP (g/kgDM)(R²=0.958, n=12, P<0.001).24h in vitro gas production (GP24h) werealso related to ME significantly (P<0.01). Prediction equation for ME using GP24hwas ME (MJ/kgDM)=3.328-0.078IVOMD (%)+0.259GP24h(R²=0.901, n=12, P<0.001).Experiment3: Prediction of metabolizable protein in feeds for meat sheepTwelve crossbred (Dorper♂×Thin-tailed Han♀) rams with permanent cannulas in the rumen andthe proximal duodenum were divided into12groups (4trial periods) according to12×4uncompletedLatin square experiment design, and fed with twelve different concentrate to forage ratio ration,0:100,8:92,16:84,24:76,32:68,40:60,48:52,56:44,64:36,72:28,80:20and88:12, respectively. Experimentcomprised four periods, each period lasted for21d, and the first14d of each experiment were for rationadaption, with sampling during d15to d21of each period. The flow of digesta to the duodenum wasdetermined using Yb and Co as dual-phase markers.15N was used as marker to calculate the bacterial N.Metabolizable protein, rumen fermentation parameters and24h fermentable organic matter weredetermined at present study. Results indicated that concentrate to forage ratio of TMR had significanteffects on ruminal pH, NH3-N and VFA (P<0.05). Metabolizable protein (MP) was significantly relatedto crude protein (CP) or digestible protein (DP)(P<0.01). Prediction equations for MP using CP or DPwere MP (g/kgDM)=-55.712+9.826CP (%)(R²=0.986, n=12, P<0.001), MP (g/kgDM)=-9.841+0.983DP (g/kgDM)(R²=0.999, n=12, P<0.001). And24h fermentable organic matter was significantlyrelated to metabolizable energy (ME) or MP (P<0.01), and the equations developed were ME(MJ/kgDM)=5.094+0.130FOM₂4h(g/kgDM)(R²=0.765, n=12, P<0.001), MP (g/kgDM)=-70.321+4.639FOM24h(g/kgDM)(R²=0.858, n=12, P<0.001).