Study On Slaughter Performance And Fat Metabolism Related Indexes Of Grazing Supplemented Fattening Beef Cattle

The experimental animals in this study were all from Xilinguole League in Inner Mongolia Autonomous Region,Ten heads of 17-18 month bulls with healthy physique and normal development were selected for comparative experiments,namely Uzhumuchin white cattle and Simmental cattle,each with 5 heads.The experiment used grazing and supplemental feeding and fattening methods for fattening.Blood was collected from the jugular vein before slaughter.After slaughter,the longissimus dorsi muscle between 12 and 13 ribs of burdock was collected as a test sample.The slaughter performance,meat quality,muscle nutrients,blood hormones related to fat metabolism and mRNA expression of genes involved in fat metabolism were studied under the same grazing supplementation conditions.The difference between the determination indexes of Uzhumuchin white cattle and Simmental cattle was analyzed by one-way ANOVA.The test results showed that:1.Meat quality:Uzhumuchin white cattle were significantly lower than Simmental cattle in pH,water rate and cooked meat rate(P<0.05),and drip loss and shear force were significantly higher than Simmental cattle(P<0.05),the water loss rate,L*,b*were higher than Simmental but the difference was not significant(P>0.05).Muscle redness a*Uzhumuchin white cattle were higher than Simmental cattle,P value was close to 0.05,and the difference approached significant.2.Nutrients:The conventional muscle nutrient composition,the crude fat content,dry matter content and ash content of Uzhumuchin white cattle were significantly higher than Simmental cattle(P<0.05),while the water content was significantly lower than Simmental cattle(P<0.05).The muscle crude protein content of Uzhumuchin white cattle was higher than Simmental cattle,but the difference was not significant(P>0.05).The total amount of amino acids,essential amino acids,non-essential amino acids,sweet amino acids and sweet umami amino acids of Uzhumuchin white cattle were significantly higher than that of Simmental(P<0.05).In the ratio of EAA/TAA and EAA/NEAA,the EAA/TAA ratios of both cows were above 40%,and the EAA/NEAA values were all above 70%.The linolenic acid content in the muscles of Uzhumuchin white cattle was significantly higher than that of Simmental(P<0.05),while the content of arachidonic acid and sinapic acid was significantly lower than that of Simmental(P<0.05).Another fatty acid content was not significantly different between the two types of cattle(P>0.05).In addition,the contents of saturated fatty acids,monounsaturated fatty acids,polyunsaturated fatty acids,n-3 series and n-6 series fatty acids were not significantly different(P>0.05).The content of manganese in the muscles of Uzhumuchin white cattle was significantly higher than that of Simmental(P<0.05).Calcium,phosphorus,magnesium,potassium,sodium and zinc were higher than those of Simmental,while copper and iron.The selenium content is lower,but there is no significant difference.3.Related indicators of fat metabolism in blood:In the blood biochemical index content,the contents of semin glucose,triglyceride,total cholesterol and low density lipoprotein cholesterol in Uzhumuchin white cattle were significantly higher than Simmental(P<0.05);High-density lipoprotein cholesterol was significantly lower than Simmental(P<0.05).Cortisol,thyroxine,triiodothyronine,glucagon,and growth honmone Uzhumuchin white cattle associated with fat metabolism were significantly lower than Simmental(P<0.05).The contents of insulin,leptin and insulin-like growth factor-1 were significantly higher than Simmental(P<0.05).4.mRNA expression of fat metabolism-related genes:The mRNA expression levels of PPARy,HSL and FASN in the longissimus dorsi muscle of Uzhumuchin white were significantly higher than those in Simmental(P<0.05).5.The slaughter rate of Uzhumuchin white cattle was significantly higher than Simmental(P<0.05),but the eye muscle area and backfat thickness were significantly lower than Simmental(P<0.05).In addition,the high-grade meat production rate of Uzhumuchin white cattle was significantly lower than Simmental cattle(P<0.05).The quality of the meat was higher than Simmental cattle,but the difference was not significant(P>0.05).