The Evaluation Of Yak Yield And Quality Grade

Yak is growing in more remote and cold areas,mostly nomadic free grazing,yak slaughter and meat trading has not formed a certain specificationyet.Therefore,our study based on Qinghai and Gannan yak,analyzed the effects of different age carcasses,carcass body structure and physiological maturity on the carcass of yak,the yak slaughter rate and different parts of meat Weight,total meat production,and PCA were used to extract the carcass index factors affecting the total meat production of yak,to establish the forecasting equation of total meat production,ultimately,the yield and grade of yak were set up in this study.The meat quality of the main parts of yak was analyzed,and the meat quality of the yak was classified according to the meat quality index.The quality grade and quality of the yak were finally determined,help Yak industryto achieve the value of yak meat.The conclusions are as follows:1.The body size of yak in different age showed an increasing trend with age,the variation was bigger,the age had a great influence on the carcass index of yak,and there were different degrees of difference between the carcass characteristics index,amongover or under four years oldyak were significant differences(p<0.05)in the indexes,such as carcass weight,carcass length,carcass depth,carcass chest depth and Loin eye area.The difference between male yak and Female Yak over the age of 4 is higher than other age groups(p<0.05).2.According to the bovine teeth and bone mineralization degree of spine 3 parts,Sacral vertebra,lumbar and thoracic vertebra,the yak physiological maturity was divided into four grades,namely,A,B,C and D.3.Yak carcass body structure 5 image index,back fat coverage,obversehip width,sidehip width,chest width,their chart of frequency distribution were normal distribute,except for the back of the fat coverage in difference age was not significant(p>0.05).The other four indexes were significant(p<0.05).The body length is consistent with the difference of carcass length in the body measurements of traditional measurements,and the two indexes of hip fullness were consistent with the 3 indexes measured in the hind leg,all showed that the yak was over 4 years old(p<0.05),which was higher than that of yak under 4 years old.4.By analyzing the yak carcass slaughter rate,obtained before the age of 4 to slaughter the male yak,after 4 years old,especially 6-year-old female yak slaughter rate increased.The parts of the meat and carcass total meat production are also over 4 years old male yak higher than under 4 years old yak.4-6 years old,the most parts of meat weight of male and female yak difference is obvious,other age male and female is small.5.By PCA factor analysis of three groups of different age and sex of yak 15 carcass index is extracted,finally it is concluded that the key factors of carcass extraction for under 4 years old and over 4 years old male yak were 4,the key factors of carcass extraction for female Yak over 4 years old were 3.Taking the total carcass yield as the dependent variable,the carcass traits of the three groups were taken as independent variables to made regression analysis.Finally,the key factors of carcass extraction were 4,4 years old The key factors of carcass extraction were 3,and the total carcass weight was taken as the dependent variable.The carcass characteristics index of each group was analyzed by regression analysis.The results showed that the carcass total Y1=-48.903+1.174×hind leg length+0.860×waist flesh+0.463×eye muscle area-0.061×chest width-3.692×10-5×back fat coverage;Y2=137.018-0.787×Hind leg length+4.936×waist flesh thickness+0.057×right hip width-0.140×side hip width-0.195×body length;Y3=-8.947+0.451×hind leg length-0.005×chest width.Finally,the yak yield grade is divided into ? grade(excellent),? grade(good),?(middle),?(poor)according to physiological maturity and carcass prediction.6.The contents of L*,a*,b*,water loss,cooking loss,shear stress,protein content,fat content,water content and six TPA characteristics of the main parts of yak showed different.The brightness values of longissimus dorsi was significantly higher than other parts(p<0.05),and the water loss rate was significantly lower(p<0.05)than other parts.While the psoas muscle is a few parts of the meat has highest water loss rate and the smallest shear force,cohesion,adhesion,and resilience.a*value of ribeye is higher than that of six other parts of the body except the tenderloin the eyeround.The a* value of flesh in the hindquarters is higher,but the protein content is higher,but the fat and water content is low,and the chewing force is larger.7.Through the yak 9 parts of the main parts of the meat of the PCA analysis,can be roughly divided into four categories,the first category,including semitendinosus,hip biceps femoris,seminal muscle,hip quadriceps;second Class includes the upper muscle,trapezius,latissimus dorsi muscle;the third category,including the back of the longest muscle;the fourth category,including psoas muscle.And then according to the weight of each part of the meat to establish the quality of yak meat quality grading standards,semitendinosus,hemi-membranemuscle,hip quadriceps,supragastric muscle,trapezius muscle,latissimus dorsi,longissimus dorsi,Are divided into A-level,B-class and C-class,three grades;hip biceps are divided into A-level and B-level two.