Study On Energy Requirement Of Hornless Xianan Cattle In Early Fattening Stage

This experiment was conducted to study the effects of different dietary energy on growth performance,blood indexes,fecal microflora and energy requirement of hornless Xianan cattle.In the experiment,25 healthy heads with similar body weight（396.71 1±45.39 kg）were randomly divided into 5 groups,i.e.group I to group V,with 7 replicates in each group.They were fed 5 experimental diets with comprehensive net energy of 4.84 MJ/kg,5.26 MJ/kg,5.68 MJ/kg,6.1 MJ/kg and 6.52 MJ/kg,respectively.The level of crude protein was the same in all groups.Three days before the end of the experiment,blood,feces,leftover materials and other samples were taken to determine the relevant indicators.The ex Periment is divided into four Parts.The experiment is divided into four parts.Section 1:effects of dietary energy on performance and apparent digestibility of hornless Xianan cattle.The results of growth performance showed that:（1）the average dry matter intake of hornless Xianan cattle was significantly lower in treatment I than in treatment III,IV and V（P<0.05）.（2）The average daily gain of treatment I and II was significantly lower than that of treatment III,IV and V（P<0.05）,and that of treatment III was significantly lower than that of treatment V（P<0.05）.（3）The feed to weight ratio of treatment I and II was significantly higher than that of treatment III,IV and V（P<0.05）,and that of treatment I was significantly higher than that of treatment II.The results of apparent digestibility showed that the digestibility of organic matter was significantly lower in treatment I than in treatment II,III,VI and V（P<0.05）;NFC digestibility of group I was significantly lower than that of group VI and V（P<0.05）,and that of group V was significantly lower than that of group IV（P<0.05）;CP digestibility in group I and V was significantly lower than that in the other three groups（P<0.05）;DM digestibility in group I was significantly lower than that in the other four groups（P<0.05）,while that in groups II and V was significantly lower than that in group IV（P<0.05）.Section 2:the effect of dietary energy level on blood indexes of hornless Xianan cattle in early fattening stage.The results showed that:（1）the effect of energy level on blood indexes of hornless Xianan cattle showed that High density lipoprotein（HDL）treatment II,V group was significantly higher than treatment I group（P<0.05）.（2）Immunoglobulin G（Ig G）showed a trend of increasing at first and then decreasing.（3）Malondialdehyde（MDA）treatment I,II,III,V group was significantly lower than treatment IV group（P<0.05）,treatment III group was significantly higher than treatment V group（P<0.05）.Section 3:effect of dietary energy level on fecal microflora of hornless Xianan cattle in early fattening stage.The results showed that:（1）the total number of OTUs in treatment I（L）was 2389,and the number of unique OTUs was 751,accounting for 25.97%of the total number of OTUs;The total number of OTUs dealing with V（H）was 2141,and the number of unique OTUs was 503,accounting for 17.39%of the total OTUs,;Among them,1638 OTUs were shared,accounting for 56.64%of the total OTUs.（2）ɑThe results of diversity showed Shannon,ACE,Chao1,observed＿Species and Pd＿whole＿Tree treatment I group was significantly lower than treatment V group（P<0.05）;There was no significant difference in Simpson（P>0.05）.（3）There were abundant taxa in treatment I（L）and treatment V（H）,among which the most abundant taxa were alpha Proteobacteria,Saccharimonadia,Coriobacteria,Streptomycetes,Melanabacteria,etc;In group V（H）,Erysipelotrichales,Bifidobacteria,Muribacteria,Clostriceae1 were the most abundant bacteria.At the gate level,the levels of Bacteroidetes and Actinobacteria in treatment I（L）were significantly lower than those in treatment V（H）,while the levels of Patescibacteria,Proteobacteria and Filaments in treatment I（L）were significantly higher than those in treatment V（H）;At the fecal genus level,the abundance of bacteria in treatment I（L）was significantly higher than that in treatment V（H）,except for turcibacter and Clostridium sensu stricto 6（P<0.05）.The test R=0.836 showed that there was significant difference between treatment I（L）and treatment V（H）（P<0.05）.Section 4:Energy requirement and model establishment of hornless Xianan cattle in early fattening stage.The results showed that:（1）An increase in dietary energy,the total energy intake and total energy digestibility of hornless Xianan cattle,II group was significantly lower than t V group（P<0.05）,group I was cons Picuous lower in than in groups III,IV,V（P<0.05）),total energy digestibility groups I,III were significantly lower than that of groups IV,V（P<0.05）,and the treatment V group（6.52MJ/kg）The highest total energy intake and total energy digestibility were 188.51 MJ/d and 74.21%.With the increase of energy level,there was a tendency to increase first and then decrease.The highest in treatment group III was52.72 MJ/d;apparent digestive energy and apparent metabolizable energy treatment groups I and II were significantly lower than treatment groups III,IV,and V（P<0.05）,of which treatment group V（6.52MJ）/kg)is the highest,and the maximum values are 131.25and 109.02 MJ/d respectively.（2）The digestibility of total energy,final body weight and daily gain I were significantly lower than those of other treatment groups（P<0.05）,and the treatment II and III were significantly lower than the treatment IV and V（P<0.05）.（3）The equations of DE and ME requirement for different body weight and daily gain were DE=0.854×w^0.75+16.921×ADG（R²=0.988,P<0.05）;ME=0.709×w^0.75+14.043×ADG（R²=0.988,P<0.05）.The requirements of DE and ME were 0.854mj/kg W^0.75d^-1 and 0.709MJ/kg W^0.75d^-1;The DE and ME 1kg weight gain were res Pectively 16.921MJ,14.043MJ.