Analysis Of Beef Quality Traits And Their Correlation With CAPN1 And CAST Gene Polymorphisms In Wandong Cattle

The quality of roughage directly affects the rumen fermentation effect and beef quality traits of Wandong cattle.In this experiment,20 Wandong cattle（bulls）weighing 492.67±33.01kg and 3.5±0.5years old were randomly divided into two groups.Oatgrass（YMC）and wheat straw（XMJ）were used as the source of roughage.Concentrate composition was the same.The pre-feeding period was 10 days and the experimental period was 60 days.At the end of the experiment,20 experimental cattle were slaughtered in batches before morning feeding.Meat samples were taken for meat quality determination,calpain activity determination and correlation analysis between CAPN1 and CAST gene polymorphisms and meat quality traits.Therefore,the relationship between YMC and XMJ as the source of roughage,meat quality traits and CAPNI,CAST gene polymorphisms was explored,which laid a theoretical foundation for the more rational and scientific application of high quality roughage in the production of Wandong cattle.The test results show that:Experiment I:Effects of Different Diets on Beef Quality Traits in Wandong cattleANKOM RFS was used to simulate rumen fermentation system in vitro,YMC group,XMJ group and control group.pH value,gas production（GP）,ammonia nitrogen（NH₃-N）,microbial mycelial protein（MCP）and volatile fatty acid（VFA）were analyzed at 12,24,36,48,60 and 72 hours of fermentation.The pH value of fermentation broth in YMC group and XMJ group decreased with the increase of fermentation time,and stabilized at about 6.42.At 24 hours of culture,the pH value of XMJ group was significantly different from that of YMC group（P<0.05）.With the extension of fermentation time,GP of YMC group and XMJ group increased gradually,and GP increased sharply from 36h to 48h.GP in YMC group was significantly higher than that in XMJ group at 60h（P<0.05）;NH₃-N concentration in YMC group and XMJ group increased gradually with the prolongation of culture time to 36-48h,NH₃-N concentration increased sharply,NH₃-N content in YMC group was significantly higher than that in XMJ group at 12,24 and 60h（P<0.05）;MCP content in YMC group was higher than that in XMJ group at 36,48 and 60h（P>0.05）;acetic acid,propionic acid and propionic acid in YMC group were not significantly higher than that in XMJ group at 36h（P>0.05）.The concentration of butyric acid in YMC group was significantly higher than that in XMJ group（P<0.05）,and the concentration of acetic acid,propionic acid and butyric acid in YMC group was significantly higher than that in XMJ group（P<0.05）.The edible quality,nutrient composition and texture of 7-9 longissimus dorsi,pectoralis and leg muscles were measured.The effects of YMC and XMJ on the quality of Wandong cattle’beef were analyzed.The results showed that the redness（a*value）and cooked meat rate of longissimus dorsi,pectoralis and leg muscles in YMC group were significantly higher than those in XMJ group（P<0.05）,while the water loss and shear force in YMC group were significantly lower than those in XMJ group（P<0.05）.The brightness（L*value）and drip loss of pectoral muscles in YMC group were significantly lower than those in XMJ group（P<0.05）,while the pH value was significantly higher than that in XMJ group（P<0.05）;the hardness of longissimus dorsi,pectoralis and leg muscles in YMC group was significantly lower than that in XMJ group（P<0.05）;the cohesion of longissimus dorsi in YMC group was lower than that in XMJ group,and there was no significant difference between the other two groups（P>0.05）.The adhesion of pectoral muscles in YMC group was significantly higher than that in XMJ group（P<0.05）.The contents of CP and Ca in the longissimus dorsi,pectoral and leg muscles of YMC group were significantly higher than those of XMJ group（P<0.05）,but the contents of EE in YMC group were significantly lower than those in XMJ group（P<0.05）.Ash content in leg muscle of YMC group was significantly lower than that of XMJ group（P<0.05）.Experiment Ⅱ:Effects of Different Diets on Calpain Activity in Muscle of Wandong cattleThe activities of troponin in longissimus dorsi,pectoralis and leg of YMC group were significantly higher than those of XMJ group（P<0.05）.The activity of troponin in longissimus dorsi was the highest,followed by leg muscle and pectoralis muscle.The activity of troponin in longissimus dorsi,pectoralis and leg of XMJ group was relatively low and basically maintained at the same level.Experiment Ⅲ:Analysis of the correlation between CAPN1 and CAST gene polymorphisms and meat quality traits in Wandong cattleThere were two genotypes of CAPN1 in Wandong cattle,AA and BB,and four single nucleotide polymorphism（SNPs）loci were found in the CAPN1 gene.The position mutation sites of intron 8 were C429G and G437A,exon 9 were G458C,intron 9 was C572T,and CAPN1 gene was moderately polymorphic（0.25<PIC<0.5）;at the CAPN1 gene polymorphism locus,Wandong cattle was extremely significant.It deviates from Hardy-Weinberg equilibrium（P<0.01）.There were two genotypes of CAST gene in Wandong cattle,CC and CT,and five SNPs were found,including intron 8,A220G,A223G and G239A,exon 9,C369T and G375A,respectively.CAST gene in Wandong cattle was moderately polymorphic（0.25<PIC<0.5）,and at CAST gene polymorphism,Wandong cattle was in Hardy-Weinberg equilibrium（P>0.05）.The AA genotype and BB genotype of CAPN1 gene of were significantly correlated with the shear stress values of longissimus dorsi,pectoralis and leg muscles,and the shear stress values of AA genotype were significantly lower than those of BB genotype（P<0.05）;other meat quality traits were not significantly correlated between AA genotype and BB genotype（P>0.05）.The shear stress values of CC genotype and CT genotype were also significantly correlated with those of longissimus dorsi,pectoralis and leg muscles of Wandong cattle,and the shear stress values of CC genotype were significantly lower than those of CT genotype（P<0.05）;other meat quality traits were not significantly correlated between CC genotype and CT genotype（P>0.05）.Conclusion:Compared with XMJ,the GP of Wandong cattle fed with YMC is higher,which can obtain better fermentation effect;feeding YMC is more conducive to maintaining rumen health,maintaining the normal survival and reproduction of rumen microorganisms,and improving the digestive efficiency of Wandong cattle;YMC can also improve the quality of Wandong cattle’ beef,increase muscle tenderness,a*value,cooked meat rate,improve the content of nutrients,and provide high-quality beef products for human beings.CAPN1 and CAST genes of meat quality traits were moderately polymorphic,but CAPN1 deviated from Hardy-Weinberg equilibrium.The SNPs loci of CAPN1 and CAST genes were significantly correlated with muscle tenderness,but not with other meat quality traits.It indicated that CAPN1 and CAST could be used as candidate genes for tenderness of Wandong cattle’ beef,laying a scientific foundation for the production of high quality beef in Wandong cattle.