Effect Of Barley Diets On The Meat Quality Of Chinese Red Steppe Cattle And Analysis Of The CPT1B Gene

As living standards continue to improve,people’s requirements for beef quality are also gradually increasing.Breeding high quality beef is an urgent need for the beef cattle industry at present.Factors affecting the quality of beef include breed,feed and age,so improving diets is a direct means of achieving the production of high quality beef based on the selection of beef cattle breeds suitable for the production of high grade beef.Barley has a higher dry matter,including crude protein,crude fat and crude fibre,than maize.In this study,we replaced some of the maize with barley on the basis of the original Chinese Red Steppes Cattle diet formulation,and investigated the effect of the barley diet on the quality of Chinese Red Steppes Cattle with the same nutritional level,with a view to optimising the diet formulation for Chinese Red Steppes Cattle fattening cattle.The expression of CPT1 B gene in different tissues of Chinese Red Steppes Cattle and the correlation between the gene polymorphism and meat quality were also examined,thus providing a molecular basis for improving the quality of beef.Specific experiments:Experiment 1: Twelve 12-month-old Chinese Red Steppes Cattle of similar weight in the same feeding environment and healthy were selected for fattening trials and randomly divided into two groups,the experimental control group(conventional diet formulation)and the experimental group(barley replacing part of the maize diet formulation).Slaughter after 12 months of fattening and determination of growth performance,slaughter traits,meat quality traits,fatty acid and amino acid content and weight of high-grade cuts of meat and quality cuts of meat.Experiment 2: Detection of CPT1 B gene expression in heart,liver,spleen,lung,kidney,duodenum,rumen tissue and longissimus dorsi muscle of cattle by q-PCR.Experiment 3: Correlation of mutant loci in the CPT1 B gene with meat quality traits by sequencing.Experimental results:1.Effect of barley diets on the quality of Chinese Red Steppes CattleGrowth performance: The growth performance values of the test group were higher than those of the control group.The daily weight gain of the control group and the experimental group were 0.56 kg and 0.59 kg respectively,and the experimental group was slightly higher than the control group,but the difference was not significant.The increment of body height in the experimental group was smaller than that in the control group,which was significant(P<0.05).There was no significant difference in body weight,body slope length,chest circumference,abdominal circumference,tube circumference and cross height(P>0.05).Slaughter performance: All values of slaughter performance were higher in the test group than in the control group.There were significant differences in pre-slaughter live weight and bone weight(P<0.05),highly significant differences in carcass weight,net meat weight,net meat percentage and eye muscle area(P<0.01),and no significant differences in slaughter rate and backfat thickness(P>0.05)Meat quality: water loss rate was higher in the test group than in the control group,with highly significant differences(P<0.01).p H,marbling and eye muscle area were higher in the test group than in the control group,but the differences were not significant(P>0.05).Flesh colour,drip loss and shear force were lower in the test group than in the control group,with nonsignificant differences(P>0.05).Fatty acid and amino acid content: there was no significant difference in amino acid content between the test and control groups,which indicates that no change in flavour was affected.Weight of high grade meat blocks: The weight of high grade meat blocks(sirloin,breast,chilli meat,rhubarb strips,top and small loin,eye,phosphorus,small yellow strips,shoulder,real steak and tail dragon)was higher in the test group than in the control group.The weights of small yellow strips,shoulder meat,real steak and tail dragon were significantly higher in the test group than in the control group(P<0.05).It indicates that the barley diet has a certain effect on improving the yield of high-grade meat blocks.2.Expression analysis of the bovine CPT1 B gene in different tissues of Chinese Red Steppes CattleThe CTP1 B gene was expressed in all tissues,and the expression was ranked from highest to lowest as spleen > duodenum > rumen > kidney > lung > heart > longissimus dorsi muscle >liver.The highest expression was found in spleen,which was significantly higher than other tissues(P<0.05),followed by duodenum and rumen,which were also significantly higher than other tissues except spleen(P<0.05),while the differences in expression in heart,liver,lung,kidney and longissimus dorsi muscle were not significant(P>0.05).3.Correlation between single nucleotide polymorphisms of CPT1 B gene and meat quality traitsA SNP site in exon 3 of CPT1 B gene were found A/C mutation existed at Chr5:186029,resulting in a change of amino acid from aspartic to propionic,and the site was not in HardyWeinberg equilibrium.Correlation analysis with meat quality traits showed significant correlations with cooked meat rate and thawing loss rate(P<0.05).In summary,the barley diet did not affect beef yield and amino acid and fatty acid content of Chinese Red Steppes Cattle,but slaughter performance,meat quality and yield of high-grade meat blocks were significantly improved;the CPT1 B gene was expressed in all tissues and the gene was significantly correlated with the cooked meat rate and thawing loss rate of the Chinese Red Steppes Cattle population,indicating that the gene may be positively correlated with beef tenderness.