| This study investigated the effects of the energy level of the start on the growth performance,blood biochemical indexes and rumen flora of Angus calves.Single factor randomized design was used with 18 head calf is divided into three groups,each group feeding start of different energy levels,which can set medium energy(MME)on the basis of "Japanese beef cattle feeding standard 2008" for ME = 12.38 MJ/kg,high-energy(HME)and low energy start(LME)in the intermediate group,respectively,on the basis of increase or decrease about1.20 MJ/kg,actual mixture ME = 13.62 MJ/kg and 11.19 MJ/kg,the rest of the management measures to strive for.Each group has 6 replicates and 1 calf per repeat.The trial period was90 days.Other feeding management measures to strive for consistency.The results showed that:1)the energy level of start had no significant effect on the growth performance of Angus calves(P > 0.05);Intake of calf dry matter(P=0.003),crude protein(P<0.001),and organic matter(P=0.02)was significantly higher in the moderate energy group than in the other two groups.The intake of neutral washing fiber(P=0.003)and acidic washing fiber(P=0.001)was significantly lower in the high-energy than in the other two groups..2)in the blood routine indexes,the number of RBC and HCT in the high-energy were significantly higher than that in the moderate energy group(P<0.01).Average red blood cell volume(MCV)in the blood,the average content of red blood cells,hemoglobin(MCH),average red blood cell hemoglobin concentration(MCHC),platelet distribution width(PDW)high energy was significantly lower than the other two groups(P< 0.01),high energy mean platelet volume(MPV)was significantly lower than other two groups(P < 0.05),platelet backlog(PCT)was significantly higher than the other two groups(P< 0.01);The content of hemoglobin(HGB)and urea nitrogen(UN)in the medium energy was significantly lower than that in the other two groups(P<0.05).Serum high density lipoprotein(HDL)content in the high energy group was significantly higher than that in the low energy(P<0.05).In terms of immunity to calves with different energy levels,the serum Ig A content in the low energy group was significantly lower than that in the other two groups(P<0.05).3)in terms of rumen fermentation parameters,the content of low energy histamine nitrogen was significantly higher than that of medium energy.The concentration of acetic acid in the rumen of calves was significantly lower in the low energy than in the other two groups(P<0.05).The ratio of valeric acid in rumen in the low energy was significantly higher than that in the other two groups(P<0.05),and the ratio of acetic acid in the low energy was significantly lower than that in the other two groups(P<0.05).The proportion of iso-butyric acid and iso-valeric acid in the intermediate energy group was significantly lower than that in the other two groups(P<0.05).The ratio of b to c in the high energy was significantly higher than that in the low energy(P<0.05).4)in terms of microbial diversity,the concentration of TM7 in the rumen of calves was significantly higher in the low energy than in the high-energy(P<0.05),and the amount of Firmicutes in the rumen was significantly higher in the high-energy than in the other two groups.Firmicutes Bulleidia,Firmicutes Eubacterium,Tenericutes Anaeroplasma,Proteobacteria Suttonella and Actinobacteria Bifidobacterium were significantly lower in the high-energy than in the other two groups(P<0.05).Therefore,within the range of energy level used in this study,the energy level did not affect the growth performance of calves,and the startt with higher energy level had a certain effect on improving the immunity,antioxidant capacity and concentration of volatile fatty acids in the rumen,but it reduced the microbial diversity in the rumen.Therefore,it is recommended that the metabolic energy of Angus calves should be around 11.19 MJ/kg. |
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