| Poultry has a short reproductive cycle and is popular worldwide as a food animal.Modern intensive farming makes the growth rate of birds faster and faster,and the growth rate of broiler chicken bones and body weight is not equal,which eventually leads to an increasing incidence of leg disease.Tibial dyschondroplasia(TD)is one of the common leg diseases in commercial broilers.Leg problems in poultry will indirectly lead to the decline of chicken quality.Livestock and poultry meat is an indispensable food source in our daily life.Chicken is an ideal choice for some people who need a low-fat,high-protein diet,and chicken is more affordable than other meat products.Morinda officinalis polysaccharide(MOP)is one of the main active components of Morinda officinalis,which can inhibit bone loss and promote bone growth and development.However,the changes in meat quality during TD in broilers and whether MOP can improve meat quality in TD broilers remains largely unknown.Study 1: Changes in breast meat quality of TD broilers and therapeutic effect of MOPIn order to explore the meat quality change of TD broiler and the improvement effect of MOP,300 1-day-old AA broilers were selected as experimental animals,and 50 mg/kg thiram was used to establish a broiler TD model.The doses of MOP(250 mg/L,500 mg/L,1000 mg/L)were used for intervention,and they were divided into control group(CON),TD group and MOP(LMOP,MMOP,HMOP)treatment group.The clinical symptoms of TD broilers under the intervention of different MOP doses were observed,and the changes of related indicators such as growth performance and breast meat quality of broilers in different periods were evaluated.The result is as follows:(1)MOP can improve the growth performance of TD broilers.Compared with the CON group,the daily gain of broilers in the TD group was significantly decreased at each stage(p < 0.05);compared with the TD group,the daily gain of the broiler chickens in the MMOP group increased significantly on the 11 th and 15 th days,and the proportion of breast muscle was significantly decreased(p < 0.05).(2)500 mg/kg MOP had a better effect on improving the meat quality of TD broiler breast muscle.Compared with the CON group,the shear force of the breast muscle in the TD group on the 7th day and the aspartic acid content on the 15 th day were significantly decreased(p < 0.05);the content of aspartic acid and threonine in the breast muscle on the 7th day,the meat color L* value,the shear force,proline content on the 11 th day,and the meat color L* value,b* value and shear force on the 15 th day were significantly increased(p < 0.05).Compared with the TD group,the L* value of broiler breast muscle color in different doses of MOP group at each stage showed a decreasing trend,and the amino acid content increased as a whole(p > 0.05).Study 2: Metabolomics-based study on the effect of MOP on metabolites in breast muscle of TD broilersIn order to investigate whether the changes of breast metabolites are related to meat quality,we collected breast muscle samples using widely targeted metabolomics techniques to study the differences of breast metabolites among CON,TD and MMOP groups at various stages.Combined with UPLC-MS /MS detection platform,self-built database and multivariate statistical analysis method,411 metabolites were identified from CON,TD and MMOP groups.Statistical analysis was conducted on identified metabolites and differential metabolites were screened out.Pearson correlation test was used to explore the potential relationship between significant differential metabolites and meat quality parameters.In addition,the secondary structure of protein was detected by raman spectroscopy to further explore the effect of MOP on the protein structure of breast muscle of TD broilers.The result is as follows:(1)Different metabolites of breast muscle are closely related to meat quality,and 500 mg/kg MOP supplementation can improve the metabolic disorder of breast muscle of TD broilers.The correlation results showed that the chenodeoxycholic acid in the breast muscle was related to the L* value and the meat color b* value of the meat color on the 7th day,the N-methyl-D-aspartic acid and the meat color L* value on the 11 th day,and 1-caffeoylquinone Nitric acid,β-hydroxyisovaleric acid and the meat color b* value,2-deoxyribose 1-phosphate,cysteine disulfide glutathione and drip loss rate on day 15 were significantly negatively correlated(p < 0.05);Cytidine and meat color L* value on the 7th day,and cygodeoxycholic acid on the 15 th day were significantly positively correlated with the meat color a* value and b* value(p < 0.05).(2)MOP may affect the protein secondary structure of broiler breast muscle in TD group,thereby affecting the type and content of metabolite amino acids in breast muscle.Compared with the CON group,the proportions of β-sheet and β-turn structures of the breast muscle protein in the MMOP group on day 7 were significantly decreased(p < 0.05),and the proportion of protein secondary structure in the other groups did not change significantly.Study 3: Study on the therapeutic effect of MOP on oxidative damage of TD breast meat qualityIn order to explore the mechanism of MOP on the improvement of breast meat quality in TD broilers,broilers in different stages of CON group,TD group and MMOP group were selected to detect oxidative markers and antioxidant enzyme activities in plasma and breast muscle tissue,and pearson correlation was performed with differential metabolites.To further explore the potential relationship between differential metabolites and antioxidant-related parameters,q RT-PCR was used to detect the expression levels of antioxidant-related genes in breast muscle tissue.The results are as follows:(1)The oxidative damage of breast muscle of TD broilers is closely related to the differential metabolites.500 mg/kg MOP may improve the quality of breast muscle by increasing the content of breast metabolites and reversing the oxidative stress of breast muscle.Compared with the CON group,the plasma T-AOC and T-SOD enzyme activities of the broiler chickens in the TD group were significantly decreased on the 7th day,and the MDA content in the breast muscle was significantly increased,and the plasma and breast muscle MDA contents in the TD group on the 15 th day were significantly increased(p < 0.05).Under the intervention of MOP,compared with the TD group,the plasma T-AOC level and T-SOD enzyme activities of the broiler chickens in the MMOP group on day 7 were significantly increased(p < 0.05).The results of correlation analysis showed that the differential metabolites such as chenodeoxycholic acid,cytidine and orotic acid were significantly correlated with antioxidant indexes.(2)MOP may reduce the oxidative damage of TD broiler breast muscle by regulating the expression of Nrf2 signaling pathway.Compared with the CON group,the gene expression levels of Nrf2,HO-1,NQO1,SOD,CAT and GPX1 in the breast muscle of the TD group on the 7th day,the gene expression levels of NQO1,SOD and CAT on the 11 th day,and the gene expression level of GPX1 on the 15 th day were all significant decreased(p < 0.05).Compared with the TD group,the gene expression levels of Nrf2,HO-1 and GPX1 in the breast muscle of the MMOP group on the 7th day,the gene expression levels of Nrf2,CAT and GPX1 on the 11 th day,and the gene expression levels of NQO1 and SOD on the 15 th day were significantly increased(p < 0.05).In conclusion,the changes in breast meat quality of TD broilers may be due to the changes in the content of metabolites by oxidative injury.Metabolomics studies screened some differential metabolic biomarkers related to meat quality and breast muscle oxidative stress.In addition,it is important that adding 500 mg/L MOP can increase the content of corresponding metabolites in meat,which is beneficial to improve the quality damage of meat when TD occurs.These results will help us to better study the mechanism of injury of breast meat quality in TD broilers,and suggest that MOP may play a role as a potentially safe and harmless Chinese herbal extract in poultry production. |
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