Effects Of Different Contents Of Oxalic On Growth And Digestion,Blood Parameters,and Rumen Function In Sheep

The purpose of this experiment was to explore the effects of different contents of oxalic acid on growth and digestion,blood index and rumen function of sheep from the aspects of growth performance,nutrient digestibility,nitrogen metabolic rate,rumen fermentation,rumen flora and blood biochemical indexes.A single factor experimental design was used to select 24 German meat merino sheep（32.08±3.43kgBW）,randomly divided into 3 treatments,8 repeats for each treatment,and 1 sheep for each repeat,the experimental treatments were in the diet 1%（T1 group）and 2%（T2 group）oxalic acid were added in the form of oxalic acid（H2C2O4）,and the control group was not added.The total test period is 60 days.The results showed that:（1）The effect of oxalic acid content on the growth performance of sheep:Compared with the control group,ADG in T2 group decreased significantly and FCR increased significantly（P<0.05）;ADG in T1 group had an upward trend and FCR decreased,but the difference was not significant（P>0.05）.（2）Effect of oxalic acid content on nutrient digestibility and nitrogen deposition of sheep:NDF digestibility was significantly higher in T1 group than control group（P<0.05）,T2 group was significantly lower than control group（P<0.05）,T2 group The digestibility of DM,OM and ADF was significantly lower than that of the other two groups（P<0.05）.The digestible nitrogen and deposited nitrogen of sheep in T2 group were significantly lower（P<0.05）,and the nitrogen deposition rate was significantly lower than that in T1 group and control group（P<0.01）.The nitrogen digestibility of the T1 group was significantly higher than that of the control group（P<0.05）,and the T2 group was significantly lower than that of the control group（P<0.05）.（3）The effect of oxalic acid content on the serum biochemical indexes of sheep:On the 15th day,compared with the control group,the serum ALP of the T1 and T2 groups decreased by 14.52 and 30.64IU/L,respectively;the serum BUN increased by 7.15 and 9.48,respectively.μmol/L.The serum CREA was significantly affected by the content of oxalic acid in the feed（P<0.01）,the T1 and T2 groups were 20.92 and 13.77 μmol/L higher than the control group,respectively.On 45th day,the blood BUN and CREA of sheep in T2 group were significantly higher than those in control group and T1 group（P<0.01）,which were 3.41,4.44 mmol/L,33.95 and 29.4μmol/L respectively.（4）The effect of oxalic acid content on serum electrolytes and trace elements of sheep:On the 15th day,the blood calcium concentration of sheep in T2 group was significantly lower than that in control group and T1 group（P<0.05）,and the blood phosphorus concentration in T1 and T2 groups was significant Higher than the control group（P<0.05）.On 45th day,the blood calcium concentration of sheep in T2 group was significantly lower than that of control group and T1 group（P<0.05）,and the blood phosphorus concentration was significantly higher than that of control group and T1 group（P<0.05）.（5）The effect of oxalic acid content on the rumen fermentation index of sheep:2 hours after feeding,the rumen pH of sheep in T2 group was significantly lower than that in T1 group,and T1 group was significantly lower than that in control group（p<0.05）.At 2 hours and 4 hours after feeding,the NH3-N concentration in the T1 group was significantly higher than that in the control group,and the NH3-N concentration in the T2 group was significantly lower than that in the control group（p<0.05）.Two hours after feeding,the acetic acid concentration of sheep in the T2 group was significantly lower than that of the control group by 12.5 mmol/L（p<0.05）.The rumen propionic acid concentration was significantly affected by the oxalic acid content in the feed at 2 hours and 4 hours after feeding（p<0.05）.At 2 hours,the T1 and T2 groups were significantly lower than the control group at 2.56 and 6.23 mmol/L;at 4 hours The T1 and T2 groups were significantly lower than the control group 3.01 and 7.04 mmol/L.In the hours after feeding,compared with the control group,the butyric acid concentration in the rumen fluid of the T1 and T2 groups decreased by 0.82 and 0.78 mmol/L,respectively;the total volatile fatty acid T2 group was significantly lower than the control group by 16.02 mmol/L.（6）The effect of oxalic acid content on the phylum and genera of the rumen microbial community of sheep:At the phylum level,before and 4 hours after eating,the Proteobacteria of the T2 group had very significant differences（P=0.007）,which were higher than the control Group 1.96%and 5.5%.The control group of fibrobacteria before feeding was significantly higher than that of T1 and T2 groups（p<0.05）,and the relative abundance of fibrinobacteria of group T1 was significantly higher than that of control group after 4h of feeding,and was significantly lower than that of group T2.Control group（p<0.05）.At the genera level,before and 4 hours after eating,the relative abundance of Prevotella₁ showed a significant decreasing trend with the addition of oxalic acid concentration in the feed（p<0.05）.The relative abundance of Bacteroides BS11 enterobacteriaceae before and 4 hours after feeding was significantly higher in the T1 group than in the control and T2 groups（p<0.05）.Rumenococcus_UCG-001 in the T2 group was significantly lower than that in the control group and the T1 group before and 4 hours after feeding（p<0.05）.In summary,in this experiment,the addition of 2% oxalic acid to the diet has a certain degree of negative impact on sheep’s growth and digestion,blood indicators,and rumen function,which reduces the daily weight gain of sheep and increases the ratio of feed to meat.Causing damage to the kidneys of sheep;and reducing the rumen pH,there is a tendency to inhibit the diversity of rumen flora,so that the production of sheep rumen acetic acid,propionic acid and butyric acid is significantly reduced.The sheep can adapt to the diet supplemented with 1%oxalic acid,and improve the digestibility of NDF and ADF and thecontent of NH3-N in rumen,which has a positive effect on growth and digestion.